JP4068534B2 - Optical frequency filter - Google Patents

Description

  The present invention relates to an optical frequency filter applied to an optical transmission system such as optical communication, optical switching, and optical information processing using optical wavelength multiplexing.

  In order to realize large-capacity communication, development of a wavelength multiplexing optical communication network technology that multiplexes and transmits a plurality of optical signals having different optical frequencies (wavelengths) on one optical fiber is being actively performed. .

  An optical frequency filter that can selectively extract only an optical signal having a specific optical frequency (wavelength) from an optical multiplexed signal composed of a plurality of optical frequencies includes an optical add / drop device, an optical cross-connect device, and an optical switch. It is indispensable for realizing. In addition, the number of multiplexed optical frequencies (wavelengths) is expected to increase further in the future due to an increase in data traffic in communication.

  Against such a background, the present inventors disclosed in Patent Document 1 shown below, a first array waveguide grating having a semiconductor optical amplifier type gate switch in an output waveguide, and a first array waveguide. A second arrayed waveguide grating connected to the output waveguide of the grating and having a semiconductor optical amplifier type gate switch in the output waveguide, and connected to the output waveguide of the second arrayed waveguide grating to merge light A new optical frequency filter composed of an optical converging circuit has been disclosed.

According to the optical frequency filter disclosed by the present inventors, it is possible to provide a new optical frequency filter that requires only a small increase in the number of control electrodes even if the number of optical frequencies increases.
JP2000-310756

  Certainly, according to the optical frequency filter disclosed by the present inventors in Patent Document 1, it is possible to provide a new optical frequency filter that requires only a small increase in the number of control electrodes even when the number of optical frequencies increases. .

  However, in the optical frequency filter disclosed in Patent Document 1 by the present inventors, noise due to amplified spontaneous emission (ASE) from the semiconductor optical amplifier type gate switch is superimposed on the output light due to its configuration. Therefore, the problem that the crosstalk deteriorates remains.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a low crosstalk optical frequency filter capable of removing ASE noise even when a semiconductor optical amplifier is used as an optical gate switch. And

  (1) In order to achieve the above object, the optical frequency filter of the present invention selectively extracts only an optical signal having a specific optical frequency from an optical multiplexed signal composed of a plurality of optical frequencies. (B) a first arrayed waveguide grating having a plurality of output waveguides each having an optical gate switch and an optical multiplexed signal having a plurality of optical frequencies, and (b) a first arrayed waveguide grating An optical signal to be output is input, a second array waveguide grating having a plurality of output waveguides each having an optical gate switch, and (c) an optical signal output from the second array waveguide grating is input. And a third arrayed waveguide grating.

In the case which is configured as this, when the direction of the first array waveguide grating is higher resolution than the second array waveguide grating, the free spectral range of the third arrayed waveguide grating Ru is configured to one channel spacing amount corresponding wider than the free spectral range of the first array waveguide grating. Hand, if the direction of the second arrayed waveguide grating is higher resolution than the first array waveguide grating, the free free spectral range of the third arrayed waveguide grating of the second array waveguide grating Ru is configured to one channel spacing amount corresponding wider spectral range.

  In the optical frequency filter of the present invention configured as described above, the optical gate switch provided in association with the output waveguide of the first arrayed waveguide grating and the output waveguide of the second arrayed waveguide grating are associated with each other. In combination with the optical gate switch provided, the optical signal of only a specific optical frequency is selectively extracted and input to the third arrayed waveguide grating. Light other than the optical frequency of the selected optical signal is It is removed by the third arrayed waveguide grating.

  In this way, in the optical frequency filter of the present invention, only an optical signal having a specific optical frequency is obtained by connecting the first array waveguide grating and the second array waveguide grating each having an optical gate switch in the output waveguide. When adopting the configuration of selectively extracting, the configuration in which light other than the optical frequency of the selected optical signal is removed by the third array waveguide grating is adopted, so that crosstalk can be reduced. Become.

(2) In order to achieve the above object, the optical frequency filter of the present invention selectively extracts an optical signal having a specific optical frequency from an optical multiplexed signal composed of a plurality of optical frequencies. (B) a first arrayed waveguide grating having a plurality of output waveguides each having an optical gate switch and an optical multiplexed signal having a plurality of optical frequencies, and (b) a first arrayed waveguide grating inputs the optical signal to be output, inputs and a second arrayed waveguide grating having a plurality of output waveguides with a light gate switches, and an optical signal output from the (c) second arrayed waveguide grating target and the third arrayed waveguide grating, (d) as an input the output optical signal of the second array waveguide grating, and the optical distribution circuit you distribute inputs the optical signals to the third arrayed waveguide grating Configure to include .

In the case which is configured as this, when the direction of the first array waveguide grating is higher resolution than the second array waveguide grating, the free spectral range of the third arrayed waveguide grating Ru is configured to one channel spacing amount corresponding wider than the free spectral range of the first array waveguide grating. Hand, if the direction of the second arrayed waveguide grating is higher resolution than the first array waveguide grating, the free free spectral range of the third arrayed waveguide grating of the second array waveguide grating Ru is configured to one channel spacing amount corresponding wider spectral range.

  In the optical frequency filter of the present invention configured as described above, the optical gate switch provided in association with the output waveguide of the first arrayed waveguide grating and the output waveguide of the second arrayed waveguide grating are associated with each other. Only the optical signal of a specific optical frequency is selectively extracted and input to the third arrayed-waveguide grating via the optical distribution circuit, and the selected optical signal is combined. Light other than the optical frequency is removed by the third arrayed waveguide grating.

  In this way, in the optical frequency filter of the present invention, only an optical signal having a specific optical frequency is obtained by connecting the first array waveguide grating and the second array waveguide grating each having an optical gate switch in the output waveguide. When adopting the configuration of selectively extracting, the configuration in which light other than the optical frequency of the selected optical signal is removed by the third array waveguide grating is adopted, so that crosstalk can be reduced. Become.

According to the optical frequency filter of the present invention, since crosstalk can be reduced, a semiconductor optical amplifier can be used as an optical gate switch of the optical frequency filter. If a semiconductor optical amplifier is used, it has an advantage that it is possible to compensate for the deterioration of the light intensity generated in the arrayed waveguide grating and the optical distribution circuit. However, if a semiconductor optical amplifier is used, the generation of ASE noise cannot be avoided. On the other hand, the optical frequency filter of the present invention can remove noise light other than the selected optical signal, and can achieve low crosstalk. Thus, according to the optical frequency filter of the present invention, a semiconductor optical amplifier can be used as the optical gate switch of the optical frequency filter.

  According to the present invention, a low crosstalk optical frequency filter can be realized. In addition, according to the present invention, in realizing this low crosstalk optical frequency filter, a large number of optical frequencies can be efficiently selected with fewer optical gate switches than in the conventional method.

  Hereinafter, an optical frequency filter according to an embodiment of the present invention will be described with reference to the drawings.

  Prior to the description of the exemplary embodiment of the present invention, a supplementary description will be given of the design of the arrayed waveguide grating.

  The arrayed waveguide grating is connected to a group of waveguides arranged in different arrays by a certain length (ΔL), two slab waveguides arranged at both ends thereof, and a slab waveguide on the input side. The device includes an input waveguide and an output waveguide connected to the slab waveguide on the output side, and has a wavelength multiplexing / demultiplexing function.

The frequency of light that can be transmitted from a specific input waveguide to a specific output waveguide of the arrayed waveguide grating is periodic. This frequency period is called a free spectral range (FSR) and is expressed by FSR = c / (n _eff · ΔL). Here, c is the speed of light, and n _eff is the effective refractive index of the arrayed waveguide.

  Also, the difference in the frequency of light output from a specific input waveguide to the adjacent output waveguide (in some cases, the difference in the frequency of light output from the adjacent input waveguide to the specific output waveguide) The channel spacing is the distance between the output waveguide and the radius of curvature of the slab waveguide at the connection point with the slab waveguide (in some cases, the distance between the input waveguide and the curvature of the slab waveguide at the connection point with the slab waveguide) Radius) and FSR.

[First Embodiment]
FIG. 1 shows a circuit configuration of an optical frequency filter in the case where the number of multiplexed wavelengths according to the first embodiment of the present invention is 16 channels (f1 to f16).

  In the figure, 401 is a first arrayed waveguide grating, 411 is a second arrayed waveguide grating, 424 is a third arrayed waveguide grating, and 435 is a 2 × 1 optical converging circuit.

  The output waveguides 403, 404, 405, and 406 of the first arrayed waveguide grating 401 are input waveguides 412 of the second arrayed waveguide grating 411 via optical gate switches 407, 408, 409, and 410, respectively. , 413, 414, 415.

  The output waveguides 416, 417, 418, 419 of the second arrayed waveguide grating 411 are input waveguides of the third arrayed waveguide grating 424 via the optical gate switches 420, 421, 422, 423, respectively. 428, 427, 426, and 425.

  Of the output waveguides 430, 431, 432, 433, and 434 of the third arrayed waveguide grating 424, the output waveguides 431 and 432 are connected to the 2 × 1 optical converging circuit 435.

  Here, the first arrayed waveguide grating 401 corresponds to the arrayed waveguide grating (number of input waveguides: 1, number of output waveguides: 4) shown in FIG. The output waveguides 403, 404, 405, and 406 correspond to the input port 101, and correspond to the output ports 111, 112, 113, and 114, respectively.

  The first arrayed waveguide grating 401 is designed such that the channel spacing is equal to the frequency spacing of the wavelength multiplexed light, and the FSR (free spectral range) is the number of output waveguides times that channel spacing, that is, four times. The transmission characteristics are as shown in FIG.

  Similarly, the second arrayed waveguide grating 411 corresponds to the arrayed waveguide grating shown in FIG. 3A (number of input waveguides: 4, number of output waveguides: 4). 413, 414, and 415 correspond to the input ports 201, 202, 203, and 204, respectively, and the output waveguides 416, 417, 418, and 419 correspond to the output ports 211, 212, 213, and 214, respectively. .

  The second arrayed waveguide grating 411 has a channel spacing equal to the FSR of the first arrayed waveguide grating 401, and the FSR of the second arrayed waveguide grating 411 outputs the channel spacing. The number of waveguides is designed to be four times, that is, four times, and the transmission characteristics are as shown in FIG.

  Further, the third arrayed waveguide grating 424 corresponds to the arrayed waveguide grating shown in FIG. 4A, and the input waveguides 425, 426, 427, 428, and 429 are respectively input ports 301, 302, 303, 304, and 305, and the output waveguides 430, 431, 432, 433, and 434 correspond to the output ports 311, 312, 313, 314, and 315, respectively.

  The third arrayed waveguide grating 424 has a channel spacing equal to the frequency spacing of the wavelength multiplexed light, that is, the channel spacing of the first arrayed waveguide grating 401, and the FSR is the FSR of the first arrayed waveguide grating 401. The number of input and output waveguides is “FSR = (channel spacing) ×× (channel spacing) ×× channel spacing”. The number of input waveguides is five so that “the number of input or output waveguides” is satisfied, and the transmission characteristics are as shown in FIG.

  That is, in the first embodiment (the same applies to the second and third embodiments described later), the channel spacing (more precisely, the transmission band) of the first arrayed waveguide grating 401 is the wavelength multiplexed light. The first arrayed waveguide grating 401 is equal to the frequency spacing, and the channel spacing (more precisely, the transmission band) of the second arrayed waveguide grating 411 is equal to four times the frequency spacing of the wavelength multiplexed light. When the resolution is higher than that of the second array waveguide grating 411, the FSR of the third array waveguide grating 424 is the first array waveguide having a high resolution such as “FSR = 5 channels”. It is designed to be wider than the FSR of the lattice 401 by one channel interval.

  By making the FSR of the third arrayed waveguide grating 424 wider than the FSR of the first arrayed waveguide grating 401 by one channel interval, as shown in FIG. 4B, the second arrayed waveguide is obtained. It becomes possible to realize that the optical signal transmitted through the grating 411 is transmitted only to the output ports 312 and 313 of the third arrayed-waveguide grating 424, so that the 2 × 1 optical converging circuit 435 with less coupling loss can be realized. It becomes possible to use.

  The operation of the optical frequency filter according to the first embodiment configured as described above will be described.

  The 16 input lights (f1 to f16) having different optical frequencies inputted from the input waveguide 402 of the first arrayed waveguide grating 401 are shown in FIG. 2B by the first arrayed waveguide grating 401. The signals are demultiplexed according to the transmission characteristics and guided to the output waveguides 403, 404, 405, and 406 of the first arrayed waveguide grating 401 (corresponding to the output ports 111, 112, 113, and 114 in FIG. 2A, respectively). .

  That is, the lights f1, f5, f9, and f13 are guided to the output waveguide 403, the lights f2, f6, f10, and f14 are guided to the output waveguide 404, and the lights f3, f7, f11, and f15 are output guided. The light of f4, f8, f12, and f16 is guided to the output waveguide 406.

  At this time, when one of the optical gate switches 407, 408, 409, 410, for example, the optical gate switch 408 is turned on, the output waveguide 404 of the first arrayed waveguide grating 401 (FIG. 2A). Only the four lights f2, f6, f10, f14 guided to the output port 112 of the second array waveguide through the input waveguide 413 (corresponding to the input port 202 of FIG. 3A). Input to the grid 411.

  Then, the four lights f2, f6, f10, and f14 are output waveguides 416, 417, 418, and 419 of the second arrayed waveguide grating 411 according to the transmission characteristics of FIG. Corresponding to output ports 211, 212, 213, and 214). That is, the light of f2 is guided to the output waveguide 419, the light of f6 is guided to the output waveguide 416, the light of f10 is guided to the output waveguide 417, and the light of f14 is guided to the output waveguide 418.

  At this time, when one of the optical gate switches 420, 421, 422, and 423, for example, the optical gate switch 422 is turned on, the light is guided to the output waveguide 418 of the corresponding second arrayed waveguide grating 411. Only the light of f14 is transmitted. Further, the light of f14 is input to the third arrayed waveguide grating 424 through the input waveguide 426 (corresponding to the input port 302 in FIG. 4A).

  Then, the light is guided to the output waveguide 432 (corresponding to the output port 313 in FIG. 4A) according to the transmission characteristics of the third arrayed waveguide grating 424 shown in FIG. 4B. Finally, the light of f14 passes through the 2 × 1 optical converging circuit 435 and is output through the output waveguide 436.

  Similarly, it is possible to select only one light other than f14 by combining the optical gate switches 407, 408, 409, 410 and the optical gate switches 420, 421, 422, 423, as shown in FIG. The signal can be output through the 2 × 1 optical converging circuit 435 through either the output waveguide 431 or the output waveguide 432 of the third arrayed waveguide grating 424.

  As described above, in the present embodiment example, since all the lights of f1 to f16 always pass through the third arrayed waveguide grating 424 that functions as an optical bandpass filter after being selected, the frequency of the selected light Excess optical components other than the above are cut off, and even when a semiconductor optical amplifier is used as an optical gate switch, it is possible to remove the ASE noise and to function as a low crosstalk optical frequency filter. is there.

  In addition, since the selected light passes through one of the output waveguides 431 and 432 at this time, it becomes possible to use the 2 × 1 optical converging circuit 435 having a small coupling loss. A filter can be realized.

  Here, in the present embodiment example, in order to facilitate the explanation of the transmission characteristics of the third arrayed waveguide grating 424, five output waveguides are described, but they are connected to the 2 × 1 optical converging circuit 435. There is no need to arrange the output waveguides 430, 433, and 434 of the third arrayed waveguide grating 424 that is not present.

[Second Embodiment]
FIG. 6 illustrates a circuit configuration of the optical frequency filter when the number of wavelength multiplexing is 16 channels (f1 to f16) according to the second embodiment of the present invention.

  In the figure, 601 is a first arrayed waveguide grating, 611 is a second arrayed waveguide grating, 626 is a third arrayed waveguide grating, 624 is a first two-input / three-output optical converging circuit, and 625 is a second. This is a 2-input 3-output optical confluence circuit.

  The output waveguides 603, 604, 605, and 606 of the first arrayed waveguide grating 601 are respectively input optical waveguides 612 of the second arrayed waveguide grating 611 via optical gate switches 607, 608, 609, and 610, respectively. , 613, 614, 615.

  Of the output waveguides 616, 617, 618, and 619 of the second arrayed waveguide grating 611, the output waveguides 616 and 617 are the first two-input three-output light via the optical gate switches 620 and 621, respectively. The output waveguides 618 and 619 are connected to the second 2-input 3-output optical merge circuit 625 via the optical gate switches 622 and 623, respectively.

  The three output waveguides of the first 2-input 3-output optical converging circuit 624 are connected to the input waveguides 627, 628, 629 of the third arrayed waveguide grating 626, respectively, and the second 2-input The three output waveguides of the three-output optical converging circuit 625 are connected to the input waveguides 630, 631, and 632 of the third arrayed waveguide grating 626, respectively.

  Here, the first arrayed waveguide grating 601 corresponds to the arrayed waveguide grating shown in FIG. 2A, the input waveguide 602 corresponds to the input port 101, and the output waveguides 603 and 604. , 605, 606 correspond to the output ports 111, 112, 113, 114, respectively. The design of the first arrayed waveguide grating 601 is the same as that of the first arrayed waveguide grating 401 shown in the first embodiment, and its transmission characteristics are as shown in FIG. .

  Similarly, the second arrayed waveguide grating 611 corresponds to the arrayed waveguide grating shown in FIG. 3A, and the input waveguides 612, 613, 614, and 615 are input ports 201, 202, and 203, respectively. , 204, and output waveguides 616, 617, 618, 619 correspond to output ports 211, 212, 213, 214, respectively. The design of the second arrayed waveguide grating 611 is the same as that of the second arrayed waveguide grating 411 shown in the first embodiment, and its transmission characteristics are as shown in FIG. .

  Further, the third arrayed waveguide grating 626 corresponds to the arrayed waveguide grating shown in FIG. 7A, and the input waveguides 627, 628, 629, 630, 631, 632 are respectively connected to the input port 501, 502, 503, 504, 505, and 506 correspond to each other, and the output waveguide 633 corresponds to the output port 511.

  The frequency interval of light output from the input waveguide adjacent to the third arrayed waveguide grating 626 to the output waveguide is equal to the frequency interval of wavelength multiplexed light, that is, the channel interval of the first arrayed waveguide grating 601. Equally, the FSR is designed to be wider by one channel interval (for 5 channels in this embodiment) than the FSR of the first arrayed waveguide grating 601 (for 4 channels in this embodiment), and The number of input waveguides is six, which is one more than “FSR = (channel interval) × (number of input waveguides)”, and the number of output waveguides is one.

  By designing the input waveguide in this manner, the input waveguide 627 (corresponding to the input port 501 in FIG. 7A) and 632 (input port 506 in FIG. 7A) of the third arrayed waveguide grating 626 are designed. )), It is possible to transmit signals having the same frequency but different diffraction orders. The transmission characteristics are as shown in FIG.

  As shown in FIG. 7B, the FSR of the third arrayed waveguide grating 626 becomes “FSR = 5 channels” which is wider than the FSR of the first arrayed waveguide grating 601 by one channel interval. It is.

  The operation of the optical frequency filter according to the second embodiment configured as described above will be described.

  The 16 input lights (f1 to f16) having different optical frequencies inputted from the input waveguide 602 of the first arrayed waveguide grating 601 are shown in FIG. 2B by the first arrayed waveguide grating 601. The signals are demultiplexed according to the transmission characteristics and guided to the output waveguides 603, 604, 605, and 606 (corresponding to the output ports 111, 112, 113, and 114 in FIG. 2A, respectively) of the first arrayed waveguide grating 601. .

  That is, the light of f1, f5, f9, and f13 is guided to the output waveguide 603, the light of f2, f6, f10, and f14 is guided to the output waveguide 604, and the lights of f3, f7, f11, and f15 are output guided. The light of f4, f8, f12, and f16 is guided to the output waveguide 606.

  At this time, when one of the optical gate switches 607, 608, 609, and 610, for example, the optical gate switch 608 is turned on, the output waveguide 604 of the first arrayed waveguide grating 601 (FIG. 2A). Only the four lights f2, f6, f10, and f14 guided to the output port 112 of the second array waveguide pass through the input waveguide 613 (corresponding to the input port 202 of FIG. 3A). Input to the grid 611.

  The four lights f2, f6, f10, and f14 are output waveguides 616, 617, 618, and 619 of the second arrayed waveguide grating 611 according to the transmission characteristics shown in FIG. Corresponding to output ports 211, 212, 213, and 214). That is, the light of f2 is guided to the output waveguide 619, the light of f6 is guided to the output waveguide 616, the light of f10 is guided to the output waveguide 617, and the light of f14 is guided to the output waveguide 618.

  At this time, when one of the optical gate switches 620, 621, 622, and 623, for example, the optical gate switch 622 is turned on, the light is guided to the output waveguide 618 of the corresponding second arrayed waveguide grating 611. Only the light of f14 is transmitted. Further, the light of f14 is input to the second 2-input 3-output optical converging circuit 625, and the input waveguides 630, 631, 632 of the third arrayed waveguide grating 626 (input port 504 in FIG. 7A). , 505, 506).

  Among these, only the light of f14 that has passed through the input waveguide 632 of the third arrayed waveguide grating 626 is output through the output waveguide 633 according to the transmission characteristics of FIG.

  Similarly, light other than f14 can be selected in combination with the optical gate switches 607, 608, 609, and 610 and the optical gate switches 620, 621, 622, and 623, and the first two inputs. The signal can be output from the output waveguide 633 through the third array waveguide grating 626 via the three-output optical merge circuit 624 or the second two-input three-output optical merge circuit 625.

  Thus, in the present embodiment example, all the light of f1 to f16 always passes through the third arrayed waveguide grating 626 that functions as an optical bandpass filter after being selected, so the frequency of the selected light Excess optical components other than the above are cut off, and even when a semiconductor optical amplifier is used as an optical gate switch, it is possible to remove the ASE noise and to function as a low crosstalk optical frequency filter. is there.

  Here, an optical gate switch, particularly a semiconductor optical amplifier, may be inserted on the output waveguides of the first and second 2-input 3-output optical converging circuits 624, 625. In this case as well, the function of the low crosstalk optical frequency filter is not impaired.

  Furthermore, in the present embodiment, the case where two 2-input 3-output optical merging circuits are used has been shown, but the same effect can be obtained even if these are combined and one 4-input 6-output optical merging circuit is used. On the contrary, the same effect can be obtained even when three or more optical confluence circuits are used.

[Third Embodiment]
FIG. 8 illustrates a circuit configuration of the optical frequency filter in the case where the number of wavelength multiplexing according to the third embodiment of the present invention is 16 channels (f1 to f16).

  In the figure, 801 is a first arrayed waveguide grating, 811 is a second arrayed waveguide grating, 833 is a third arrayed waveguide grating, 824 to 827 are 1 × 2 optical branch circuits, and 828 to 832 are 2 ×. This is a one-light confluence circuit.

  The output waveguides 803, 804, 805, and 806 of the first arrayed waveguide grating 801 are input waveguides 812 of the second arrayed waveguide grating 811 through optical gate switches 807, 808, 809, and 810, respectively. , 813, 814, 815.

  The output waveguides 816, 817, 818, and 819 of the second arrayed waveguide grating 811 are connected to 1 × 2 optical branch circuits 824, 825, and 826 via optical gate switches 820, 821, 822, and 823, respectively. 827.

  One of the two output waveguides of the 1 × 2 optical branch circuit 824 is connected to the 2 × 1 optical junction circuit 828, and one of the two output waveguides of the 1 × 2 optical branch circuit 825 is 2 × 1. One of the two output waveguides of the 1 × 2 optical branching circuit 826 is connected to the 2 × 1 optical converging circuit 830 while being connected to the optical converging circuit 829 and the other is connected to the 2 × 1 optical converging circuit 830. The other is connected to the 2 × 1 optical junction circuit 831, and one of the two output waveguides of the 1 × 2 optical branch circuit 827 is connected to the 2 × 1 optical junction circuit 831, and the other Are connected to a 2 × 1 optical converging circuit 832.

  Further, the output waveguides of the 2 × 1 optical converging circuits 828, 829, 830, 831 and 832 are connected to the input waveguides 838, 837, 836, 835 and 834 of the third arrayed waveguide grating 833, respectively. .

  Here, the first arrayed waveguide grating 801 corresponds to the arrayed waveguide grating shown in FIG. 2A, the input waveguide 802 corresponds to the input port 101, and the output waveguides 803 and 804. , 805, and 806 correspond to the output ports 111, 112, 113, and 114, respectively. The design of the first arrayed waveguide grating 801 is the same as that of the first arrayed waveguide grating 401 shown in the first embodiment, and the transmission waiting property is as shown in FIG. is there.

  Similarly, the second arrayed waveguide grating 811 corresponds to the arrayed waveguide grating shown in FIG. 3A, and the input waveguides 812, 813, 814, and 815 are input ports 201, 202, and 203, respectively. 204, and output waveguides 816, 817, 818, and 819 correspond to output ports 211, 212, 213, and 214, respectively. The design of the second arrayed waveguide grating 811 is the same as that of the second arrayed waveguide grating 411 shown in the first embodiment, and its transmission characteristics are as shown in FIG. .

  Further, the third arrayed waveguide grating 833 corresponds to the arrayed waveguide grating shown in FIG. 9A, and the input waveguides 834, 835, 836, 837, 838 are input ports 701, 702, respectively. 703, 704, and 705, and the output waveguide 839 corresponds to the output port 711.

  The frequency interval of the light output from the adjacent input waveguide to the output waveguide of the third arrayed waveguide grating 833 is the frequency interval of the wavelength multiplexed light, that is, the channel interval of the first arrayed waveguide grating 801. Equally, the FSR is designed to be wider by one channel interval (for 5 channels in this embodiment) than the FSR of the first arrayed waveguide grating 801 (for 4 channels in this embodiment), and The number of input waveguides is five so that “FSR = (channel interval) × (number of input waveguides)” is satisfied, the number of output waveguides is one, and the transmission characteristics thereof are as shown in FIG. 9B. It has become.

  As shown in FIG. 9B, the FSR of the third arrayed waveguide grating 833 is “FSR = 5 channels” which is wider than the FSR of the first arrayed waveguide grating 801 by one channel interval. It is.

  The operation of the optical frequency filter according to the third embodiment configured as described above will be described.

  16 input lights (f1 to f16) having different optical frequencies inputted from the input waveguide 802 of the first arrayed waveguide grating 801 are transmitted through the first arrayed waveguide grating 801 in FIG. 2B. The signals are demultiplexed according to the characteristics and guided to the output waveguides 803, 804, 805, and 806 of the first arrayed waveguide grating 801 (corresponding to the output ports 111, 112, 113, and 114 in FIG. 2A, respectively).

  That is, the light of f1, f5, f9, and f13 is guided to the output waveguide 803, the light of f2, f6, f10, and f14 is guided to the output waveguide 804, and the lights of f3, f7, f11, and f15 are output guided. Guided to the waveguide 805, the light of f 4, f 8, f 12, f 16 is guided to the output waveguide 806.

  At this time, when one of the optical gate switches 807, 808, 809, and 810, for example, the optical gate switch 808 is turned on, the output waveguide 804 of the first arrayed waveguide grating 801 (FIG. 2A). Only the four lights f2, f6, f10, f14 guided to the output port 112 of the second array waveguide through the input waveguide 813 (corresponding to the input port 202 of FIG. 3A). Input to the grid 811.

  Then, these four lights f2, f6, f10, and f14 are output waveguides 816, 817, 818, and 819 of the second arrayed waveguide grating 811 according to the transmission characteristics of FIG. Corresponding to output ports 211, 212, 213, and 214). That is, the light of f2 is guided to the output waveguide 819, the light of f6 is guided to the output waveguide 816, the light of f10 is guided to the output waveguide 817, and the light of f14 is guided to the output waveguide 818.

  At this time, when one of the optical gate switches 820, 821, 822, and 823, for example, the optical gate switch 822 is turned on, it is guided to the output waveguide 818 of the corresponding second arrayed waveguide grating 811. Only the light of f14 is transmitted. Further, the light of f14 passes through the 1 × 2 optical branch circuit 826 and is branched into the 2 × 1 optical merge circuit 830 and the 2 × 1 optical merge circuit 831. Of these, the transmission in FIG. According to the characteristics, the light of f14 that has passed through the 2 × 1 optical converging circuit 830 is input from the input waveguide 836 to the third arrayed waveguide grating 833 and output through the output waveguide 839.

  Similarly, it is possible to select only one light other than f14 by a combination of the optical gate switches 807, 808, 809, and 810 and the optical gate switches 820, 821, 822, and 823, and the corresponding 1 × 2 The light can be output from the output waveguide 839 through the third arrayed waveguide grating 833 via the optical branching circuit and the 2 × 1 optical converging circuit.

  In this way, in this embodiment example, since all the light of f1 to f16 always passes through the third arrayed waveguide grating 833 that functions as an optical bandpass filter after being selected, the frequency of the selected light Excess optical components other than the above are cut off, and even when a semiconductor optical amplifier is used as an optical gate switch, it is possible to remove the ASE noise and to function as a low crosstalk optical frequency filter. is there.

  Here, an optical gate switch, particularly a semiconductor optical amplifier, may be inserted on either or both of the output waveguide of the 1 × 2 optical branch circuit and the output waveguide of the 2 × 1 optical junction circuit. In this case as well, the function of the low crosstalk optical frequency filter is not impaired.

  In the first, second, and third embodiment examples described above, the channel spacing of the second arrayed waveguide grating is the FSR of the first arrayed waveguide grating (specifically, FSR = 4 channels). As explained in “Embodiment 5” of Patent Document 1 disclosed by the present inventors, the channel spacing of the second arrayed waveguide grating (for each channel, if expressed accurately) It is also possible to set the transmission band of the first arrayed waveguide grating below the FSR.

  That is, as apparent from the transmission characteristics of the second arrayed waveguide grating shown in FIG. 3B, when signal light is input to the input port 201, only f1 passes through the output port 211. In addition, the light passing through the output ports 211, 212, 213, 214 is limited to one light. From this, the channel spacing of the second arrayed waveguide grating can be set to be equal to or less than the FSR of the first arrayed waveguide grating.

To set the channel spacing of the second array waveguide grating below FSR of the first array waveguide grating, represents the channel spacing of the second array waveguide grating Delta] f _F, the transmission band of each channel and the Delta] f _t If, as shown in FIG. 10, changing the pitch between the input waveguide and the slab waveguide of the second array waveguide grating, furthermore, it is realized by narrowing the Delta] f _t without changing the Delta] f _F .

In this way, when narrowing the transmission band Delta] f _t for each channel, in place of the transmission characteristic of the second arrayed waveguide grating shown in FIG. 3 (b), passing light passing original and its front and rear light It is possible to realize a transmission characteristic that can be transmitted (in the extreme case, a transmission characteristic that allows only light that is originally allowed to pass through), thereby greatly improving crosstalk.

[Fourth Embodiment]
FIG. 11 shows a circuit configuration of an optical frequency filter when the number of wavelength multiplexing is 16 channels (f1 to f16) according to the fourth embodiment of the present invention.

  In the figure, reference numeral 1301 denotes a first arrayed waveguide grating, 1311 denotes a second arrayed waveguide grating, 1324 denotes a third arrayed waveguide grating, and 1335 denotes a 2 × 1 optical merging circuit.

  The output waveguides 1303, 1304, 1305, and 1306 of the first arrayed waveguide grating 1301 are respectively input optical waveguides 1312 of the second arrayed waveguide grating 1311 via optical gate switches 1307, 1308, 1309, and 1310, respectively. , 1313, 1314, 1315.

  The output waveguides 1316, 1317, 1318, and 1319 of the second arrayed waveguide grating 1311 are input waveguides of the third arrayed waveguide grating 1324 through the optical gate switches 1320, 1321, 1322, and 1323, respectively. 1325, 1326, 1327 and 1328 are connected.

  Of the output waveguides 1330, 1331, 1332, 1333, and 1334 of the third arrayed waveguide grating 1324, the output waveguides 1330 and 1331 are connected to the 2 × 1 optical merge circuit 1335.

  Here, the second arrayed waveguide grating 1311 corresponds to the arrayed waveguide grating (number of input waveguides: 4, number of output waveguides: 4) shown in FIG. 1313, 1314, 1315 correspond to the input ports 1101, 1102, 1103, 1104, respectively, and the output waveguides 1316, 1317, 1318, 1319 correspond to the output ports 1111, 1112, 1113, 1114, respectively. .

  The second arrayed waveguide grating 1311 is designed such that the channel interval is equal to the frequency interval of the wavelength multiplexed light, and the FSR is the number of input (exit) force waveguides multiplied by the channel interval, that is, four times. The transmission characteristics are as shown in FIG.

  The first arrayed waveguide grating 1301 corresponds to the arrayed waveguide grating shown in FIG. 13A (number of input waveguides: 1, number of output waveguides: 4), and the input waveguide 1302 is input. The output waveguides 1303, 1304, 1305, and 1306 correspond to the output ports 1011, 1012, 1013, and 1014, respectively.

  The first arrayed waveguide grating 1301 has a channel spacing equal to the FSR of the second arrayed waveguide grating 1311, and the FSR of the first arrayed waveguide grating 1301 outputs the channel spacing. The number of waveguides is designed to be four times, that is, four times, and the transmission characteristics are as shown in FIG.

  Further, the third arrayed waveguide grating 1324 corresponds to the arrayed waveguide grating shown in FIG. 14A, and the input waveguides 1325, 1326, 1327, 1328, and 1329 are respectively input ports 1201, 1202, and 1202. 1203, 1304, 1205, and output waveguides 1330, 1331, 1332, 1333, and 1334 correspond to output ports 1211, 1212, 1213, 1214, and 1215, respectively.

  The third arrayed waveguide grating 1324 has a channel spacing equal to the frequency spacing of the wavelength multiplexed light, that is, the channel spacing of the second arrayed waveguide grating 1311, and the FSR is the FSR of the second arrayed waveguide grating 1311. The number of input and output waveguides is “FSR = (channel spacing) ×× (channel spacing) ×× channel spacing”. The number of the input waveguides or the number of the output waveguides is “5” so that “the input or output waveguide number” is satisfied, and the transmission characteristics are as shown in FIG.

  That is, in the fourth embodiment (the same applies to the fifth and sixth embodiments described later), the channel spacing (more precisely, the transmission band) of the second arrayed waveguide grating 1311 is the wavelength multiplexed light. The second arrayed waveguide grating 1311 is equal to the frequency spacing, and the channel spacing (precisely the transmission band) of the first arrayed waveguide grating 1301 is equal to four times the frequency spacing of the wavelength multiplexed light. When the resolution is higher than that of the first arrayed waveguide grating 1301, the FSR of the third arrayed waveguide grating 1324 is a second arrayed waveguide having a high resolution such as “FSR = 5 channels”. It is designed to be wider than the FSR of the grating 1311 by one channel interval.

  By making the FSR of the third arrayed waveguide grating 1324 wider than the FSR of the second arrayed waveguide grating 1311 by one channel interval, as shown in FIG. 14B, the second arrayed waveguide is obtained. It becomes possible to realize that the optical signal transmitted through the grating 1311 is transmitted only to the output ports 1211 and 1212 of the third arrayed waveguide grating 1324, thereby enabling the 2 × 1 optical converging circuit 1335 with less coupling loss. It becomes possible to use.

  The operation of the optical frequency filter according to the fourth embodiment configured as described above will be described.

  Sixteen input lights (f1 to f16) having different optical frequencies inputted from the input waveguide 1302 of the first arrayed waveguide grating 1301 are transmitted by the first arrayed waveguide grating 1301 in FIG. 13B. The signals are demultiplexed according to the characteristics and guided to the output waveguides 1303, 1304, 1305, and 1306 (corresponding to the output ports 1011, 1012, 1013, and 1014 in FIG. 13A), respectively, of the first arrayed waveguide grating 1301.

  That is, the light of f1, f2, f3, and f4 is guided to the output waveguide 1303, the light of f5, f6, f7, and f8 is guided to the output waveguide 1304, and the lights of f9, f10, f11, and f12 are output. The light is guided to the waveguide 1305, and the lights of f 13, f 14, f 15, and f 16 are guided to the output waveguide 1306.

  At this time, when one of the optical gate switches 1307, 1308, 1309, and 1310, for example, the optical gate switch 1308 is turned on, the output waveguide 1304 of the first arrayed waveguide grating 1301 (FIG. 13A). Only the four lights f5, f6, f7, and f8 guided to the output port 1012 of FIG. 12A pass through the input waveguide 1313 (corresponding to the input port 1102 of FIG. 12A) and the second array waveguide. Input to the grid 1311.

  The four lights f5, f6, f7, and f8 are output waveguides 1316, 1317, 1318, and 1319 of the second arrayed waveguide grating 1311 according to the transmission characteristics of FIG. Corresponding to output ports 1111, 1112, 1113, and 1114). That is, the light of f5 is guided to the output waveguide 1319, the light of f6 is guided to the output waveguide 1316, the light of f7 is guided to the output waveguide 1317, and the light of f8 is guided to the output waveguide 1318.

  At this time, when one of the optical gate switches 1320, 1321, 1322, 1323, for example, the optical gate switch 1322 is turned on, it is guided to the output waveguide 1318 of the corresponding second arrayed waveguide grating 1311. Only the light of f8 is transmitted. Further, the light of f8 is input to the third arrayed waveguide grating 1324 through the input waveguide 1327 (corresponding to the input port 1203 in FIG. 14A).

  Then, the light is guided to the output waveguide 1330 (corresponding to the output port 1211 of FIG. 14A) according to the transmission characteristics of the third arrayed waveguide grating 1324 shown in FIG. Finally, the light of f8 passes through the 2 × 1 optical combining circuit 1335 and is output through the output waveguide 1336.

  Similarly, light other than f8 can be selected in combination with the optical gate switches 1303, 1304, 1305, and 1306 and the optical gate switches 1320, 1321, 1322, and 1323, and the third array conductor is selected. The signal can be output through the 2 × 1 optical converging circuit 1335 through either the output waveguide 1330 or the output waveguide 1331 of the waveguide grating 1324.

  In this way, in the present embodiment example, since all the light of f1 to f16 always passes through the third arrayed waveguide grating 1324 that functions as an optical bandpass filter after being selected, the frequency of the selected light Excess optical components other than the above are cut off, and even when a semiconductor optical amplifier is used as an optical gate switch, it is possible to remove the ASE noise and to function as a low crosstalk optical frequency filter. is there.

  In addition, since the selected light passes through either one of the output waveguides 1330 and 1331 at this time, it becomes possible to use the 2 × 1 optical converging circuit 1335 with a small coupling loss, thereby reducing the optical frequency of the low loss. A filter can be realized.

  Here, in this embodiment example, in order to facilitate the explanation of the transmission characteristics of the third arrayed waveguide grating 1324, five output waveguides are described, but the output waveguides are connected to the 2 × 1 optical converging circuit 1335. There is no need to arrange the output waveguides 1332, 1333, and 1334 of the third arrayed waveguide grating 1324 that is not present.

[Fifth Embodiment]
FIG. 15 illustrates a circuit configuration of the optical frequency filter in the case where the number of wavelength division multiplexing is 16 channels (f1 to f16) according to the fifth embodiment of the present invention.

  In the figure, 1501 is a first arrayed waveguide grating, 1511 is a second arrayed waveguide grating, 1526 is a third arrayed waveguide grating, 1524 is a first two-input three-output optical converging circuit, and 1525 is a second This is a 2-input 3-output optical confluence circuit.

  The output waveguides 1503, 1504, 1505 and 1506 of the first arrayed waveguide grating 1501 are respectively input optical waveguides 1512 of the second arrayed waveguide grating 1511 via optical gate switches 1507, 1508, 1509 and 1510, respectively. , 1513, 1514, 1515.

  Of the output waveguides 1516, 1517, 1518, and 1519 of the second arrayed waveguide grating 1511, the output waveguides 1516 and 1517 are the first two-input three-output light via the optical gate switches 1520 and 1521, respectively. The output waveguides 1518 and 1519 are connected to the second 2-input 3-output optical merge circuit 1525 through the optical gate switches 1522 and 1523.

  The three output waveguides of the first 2-input 3-output optical converging circuit 1524 are connected to the input waveguides 1527, 1528, 1529 of the third array waveguide grating 1526, respectively, and the second 2-input The three output waveguides of the three-output optical converging circuit 1525 are connected to the input waveguides 1530, 1531, and 1532 of the third arrayed waveguide grating 1526, respectively.

  Here, the first arrayed waveguide grating 1501 corresponds to the arrayed waveguide grating shown in FIG. 13A, the input waveguide 1502 corresponds to the input port 1001, and the output waveguides 1503 and 1504. , 1505, 1506 correspond to the output ports 1011, 1012, 1013, 1014, respectively. The design of the first arrayed waveguide grating 1501 is the same as that of the first arrayed waveguide grating 1301 shown in the fourth embodiment, and its transmission characteristics are as shown in FIG. .

  Similarly, the second arrayed waveguide grating 1511 corresponds to the arrayed waveguide grating shown in FIG. 12A, and the input waveguides 1512, 1513, 1514, and 1515 are input ports 1101, 1102, and 1103, respectively. , 1104, and output waveguides 1516, 1517, 1518, 1519 correspond to the output ports 1111, 1112, 1113, 1114, respectively. The design of the second arrayed waveguide grating 1511 is the same as that of the second arrayed waveguide grating 1311 shown in the fourth embodiment, and its transmission characteristics are as shown in FIG. .

  Further, the third arrayed waveguide grating 1526 corresponds to the arrayed waveguide grating shown in FIG. 16A, and the input waveguides 1527, 1528, 1529, 1530, 1531, and 1532 are input ports 1401, 1402, 1403, 1404, 1405, and 1406 correspond to each other, and the output waveguide 1533 corresponds to the output port 1411.

  The frequency interval of light output from the input waveguide adjacent to the third arrayed waveguide grating 1526 to the output waveguide is equal to the frequency interval of wavelength multiplexed light, that is, the channel interval of the second arrayed waveguide grating 1511. Equally, the FSR is designed to be wider by one channel interval (for 5 channels in this embodiment) than the FSR of the second arrayed waveguide grating 1511 (for 4 channels in this embodiment), and The number of input waveguides is six, which is one more than “FSR = (channel interval) × (number of input waveguides)”, and the number of output waveguides is one.

  By designing the input waveguide in this way, the input waveguide 1527 (corresponding to the input port 1401 of FIG. 16A) and 1532 of the third arrayed waveguide grating 1526 (input port 1406 of FIG. 16A). )), It is possible to transmit signals having the same frequency but different diffraction orders. The transmission characteristics are as shown in FIG.

  As shown in FIG. 16B, the FSR of the third arrayed waveguide grating 1526 is “FSR = 5 channels” which is wider than the FSR of the second arrayed waveguide grating 1511 by one channel interval. It is.

  The operation of the optical frequency filter according to the fifth embodiment configured as described above will be described.

  Sixteen input lights (f1 to f16) waiting for different optical frequencies input from the input waveguide 1502 of the first arrayed waveguide grating 1501 are transmitted by the first arrayed waveguide grating 1501 in FIG. 13B. The signals are demultiplexed according to the characteristics and guided to the output waveguides 1503, 1504, 1505, 1506 (corresponding to the output ports 1011, 1012, 1013, 1014 in FIG. 13A respectively) of the first arrayed waveguide grating 1501.

  That is, the light of f1, f2, f3, and f4 is guided to the output waveguide 1503, the light of f5, f6, f7, and f8 is guided to the output waveguide 1504, and the lights of f9, f10, f11, and f12 are output guided. Guided to the waveguide 1505, the light of f 13, f 14, f 15, and f 16 is guided to the output waveguide 1506.

  At this time, when one of the optical gate switches 1507, 1508, 1509, 1510, for example, the optical gate switch 1508 is turned on, the output waveguide 1504 of the first arrayed waveguide grating 1501 (FIG. 13A). Only the four lights f5, f6, f7, and f8 guided to the output port 1012 of the second array waveguide pass through the input waveguide 1513 (corresponding to the input port 1102 of FIG. 12A). Input to the grid 1511.

  The four lights f5, f6, f7, and f8 are output waveguides 1516, 1517, 1518, and 1519 of the second arrayed waveguide grating 1511 according to the transmission characteristics of FIG. Corresponding to output ports 1111, 1112, 1113, and 1114). That is, the light of f5 is guided to the output waveguide 1519, the light of f6 is guided to the output waveguide 1516, the light of f7 is guided to the output waveguide 1517, and the light of f8 is guided to the output waveguide 1518.

  At this time, when one of the optical gate switches 1520, 1521, 1522, and 1523, for example, the optical gate switch 1522 is turned on, the light is guided to the output waveguide 1518 of the corresponding second arrayed waveguide grating 1511. Only the light of f8 is transmitted. Further, the light of f8 is input to the second 2-input 3-output optical combining circuit 1525, and the input waveguides 1527, 1528, 1529 of the third arrayed waveguide grating 1526 (input port 1401 in FIG. 16A). , 1402, 1403).

  Among these, only the light of f8 that has passed through the input waveguide 1527 of the third arrayed waveguide grating 1526 is output through the output waveguide 1533 in accordance with the transmission characteristics of FIG.

  Similarly, light other than f8 can be selected in combination with the optical gate switches 1507, 1508, 1509, 1510 and the optical gate switches 1520, 1521, 1522, 1523, and the first two inputs The signal can be output from the output waveguide 1533 through the third array waveguide grating 1526 via the three-output optical merge circuit 1524 or the second two-input three-output optical merge circuit 1525.

  In this way, in the present embodiment example, since all the light of f1 to f16 always passes through the third arrayed waveguide grating 1526 that functions as an optical bandpass filter after being selected, the frequency of the selected light Excess optical components other than the above are cut off, and even when a semiconductor optical amplifier is used as an optical gate switch, it is possible to remove the ASE noise and to function as a low crosstalk optical frequency filter. is there.

  Here, an optical gate switch, particularly a semiconductor optical amplifier, may be inserted on the output waveguides of the first and second 2-input 3-output optical merge circuits 1524, 1525. In this case as well, the function of the low crosstalk optical frequency filter is not impaired.

  Furthermore, in the present embodiment, the case where two 2-input 3-output optical merging circuits are used has been shown, but the same effect can be obtained even if these are combined and one 4-input 6-output optical merging circuit is used. On the contrary, the same effect can be obtained even when three or more optical confluence circuits are used.

[Sixth Embodiment]
FIG. 17 illustrates a circuit configuration of an optical frequency filter according to the sixth embodiment of the present invention when the wavelength multiplexing number is 16 channels (f1 to f16).

  In the figure, 1701 is a first arrayed waveguide grating, 1711 is a second arrayed waveguide grating, 1733 is a third arrayed waveguide grating, 1724 to 1727 are 1 × 2 optical branch circuits, and 1728 to 1732 are 2 ×. This is a one-light confluence circuit.

  The output waveguides 1703, 1704, 1705, and 1706 of the first array waveguide grating 1701 are respectively input optical waveguides 1712 of the second array waveguide grating 1711 via optical gate switches 1707, 1708, 1709, and 1710, respectively. , 1713, 1714, 1715.

  The output waveguides 1716, 1717, 1718, and 1719 of the second arrayed waveguide grating 1711 are connected to 1 × 2 optical branching circuits 1724, 1725, 1726, and 1720 via optical gate switches 1720, 1721, 1722, and 1723, respectively. 1727.

  One of the two output waveguides of the 1 × 2 optical branch circuit 1724 is connected to the 2 × 1 optical junction circuit 1728, and one of the two output waveguides of the 1 × 2 optical branch circuit 1725 is 2 × 1. One of the two output waveguides of the 1 × 2 optical branch circuit 1726 is connected to the 2 × 1 optical junction circuit 1730 while being connected to the optical junction circuit 1729 and the other to the 2 × 1 optical junction circuit 1730. The other is connected to the 2 × 1 optical junction circuit 1731, and one of the two output waveguides of the 1 × 2 optical branch circuit 1727 is connected to the 2 × 1 optical junction circuit 1731, and the other Are connected to a 2 × 1 optical converging circuit 1732.

  Further, the output waveguides of the 2 × 1 optical converging circuits 1728, 1729, 1730, 1731, and 1732 are connected to the input waveguides 1734, 1735, 1736, 1737, and 1738 of the third arrayed waveguide grating 1733, respectively. .

  Here, the first arrayed waveguide grating 1701 corresponds to the arrayed waveguide grating shown in FIG. 13A, the input waveguide 1702 corresponds to the input port 1001, and the output waveguides 1703 and 1704. , 1705, 1706 correspond to the output ports 1011, 1012, 1013, 1014, respectively. The design of the first arrayed waveguide grating 1701 is the same as that of the first arrayed waveguide grating 1301 shown in the fourth embodiment, and its transmission characteristics are as shown in FIG. .

  Similarly, the second arrayed waveguide grating 1711 corresponds to the arrayed waveguide grating shown in FIG. 12A, and the input waveguides 1712, 1713, 1714, and 1715 are input ports 1101, 1102, and 1103, respectively. , 1104, and output waveguides 1716, 1717, 1718, 1719 correspond to the output ports 1111, 1112, 1113, 1114, respectively. The design of the second arrayed waveguide grating 1711 is the same as that of the fourth arrayed waveguide grating 1311 shown in the fourth embodiment, and its transmission characteristics are as shown in FIG. .

  Further, the third arrayed waveguide grating 1733 corresponds to the arrayed waveguide grating shown in FIG. 18A, and the input waveguides 1734, 1735, 1736, 1737, 1738 are input ports 1601, 1602, respectively. 1603, 1604, and 1605, and the output waveguide 1739 corresponds to the output port 1611.

  The frequency interval of the light output from the input waveguide adjacent to the third arrayed waveguide grating 1733 to the output waveguide is the frequency interval of the wavelength multiplexed light, that is, the channel interval of the second arrayed waveguide grating 1711. Equally, the FSR is designed to be wider by one channel interval (for 5 channels in this embodiment) than the FSR of the second arrayed waveguide grating 1711 (for 4 channels in this embodiment), and The number of input waveguides is five so that “FSR = (channel interval) × (number of input waveguides)” is satisfied, the number of output waveguides is one, and the transmission characteristics thereof are as shown in FIG. It has become.

  As shown in FIG. 18B, the FSR of the third arrayed waveguide grating 1733 is “FSR = 5 channels” which is wider than the FSR of the second arrayed waveguide grating 1711 by one channel interval. It is.

  The operation of the optical frequency filter according to the sixth embodiment configured as described above will be described.

  Sixteen input lights (f1 to f16) having different optical frequencies inputted from the input waveguide 1702 of the first arrayed waveguide grating 1701 are transmitted by the first arrayed waveguide grating 1701 in FIG. 13B. The signals are demultiplexed according to the characteristics and guided to the output waveguides 1703, 1704, 1705, and 1706 (corresponding to the output ports 1011, 1012, 1013, and 1014 in FIG. 13A), respectively, of the first arrayed waveguide grating 1701.

  That is, the light of f1, f2, f3, and f4 is guided to the output waveguide 1703, the light of f5, f6, f7, and f8 is guided to the output waveguide 1704, and the lights of f9, f10, f11, and f12 are output guided. The light is guided to the waveguide 1705, and the lights of f 13, f 14, f 15, and f 16 are guided to the output waveguide 1706.

  At this time, when one of the optical gate switches 1707, 1708, 1709, and 1710, for example, the optical gate switch 1708 is turned on, the output waveguide 1704 of the first arrayed waveguide grating 1701 (FIG. 13A). Only the four lights f5, f6, f7, f8 guided to the output port 1012 of the second array waveguide pass through the input waveguide 1713 (corresponding to the input port 1102 of FIG. 12A). Input to the grid 1711.

  These four lights f5, f6, f7, and f8 are output waveguides 1716, 1717, 1718, and 1719 of the second arrayed waveguide grating 1711 according to the transmission characteristics of FIG. Corresponding to output ports 1111, 1112, 1113, and 1114). That is, the light of f5 is guided to the output waveguide 1719, the light of f6 is guided to the output waveguide 1716, the light of f7 is guided to the output waveguide 1717, and the light of f8 is guided to the output waveguide 1718.

  At this time, when one of the optical gate switches 1720, 1721, 1722, and 1723, for example, the optical gate switch 1722 is turned on, it is guided to the output waveguide 1718 of the corresponding second arrayed waveguide grating 1711. Only the light of f8 is transmitted. Further, the light of f8 passes through the 1 × 2 optical branch circuit 1726 and is branched into the 2 × 1 optical merge circuit 1730 and the 2 × 1 optical merge circuit 1731. Of these, the transmission in FIG. According to the characteristics, the light of f8 that has passed through the 2 × 1 optical converging circuit 1730 is input from the input waveguide 1736 to the third arrayed waveguide grating 1733 and output through the output waveguide 1739.

  Similarly, light other than f8 can be selected in combination with the optical gate switches 1707, 1708, 1709, 1710 and the optical gate switches 1720, 1721, 1722, 1723, and the corresponding 1 × 2 The light can be output from the output waveguide 1739 through the third arrayed waveguide grating 1733 via the optical branching circuit and the 2 × 1 optical converging circuit.

  In this way, in this embodiment example, since all the light of f1 to f16 always passes through the third arrayed waveguide grating 1733 that functions as an optical bandpass filter after being selected, the frequency of the selected light Excess optical components other than the above are cut off, and even when a semiconductor optical amplifier is used as an optical gate switch, it is possible to remove the ASE noise and to function as a low crosstalk optical frequency filter. is there.

  Here, an optical gate switch may be inserted on either or both of the output waveguide of the 1 × 2 optical branch circuit and the output waveguide of the 2 × 1 optical junction circuit, and a semiconductor optical amplifier may be inserted in the waiting state. . In this case as well, the function of the low crosstalk optical frequency filter is not impaired.

  By using the optical frequency filter of the present invention, a highly accurate optical add / drop device, optical cross-connect device, and optical switch can be realized.

1 is a configuration diagram of a first exemplary embodiment of the present invention. It is explanatory drawing of the array waveguide grating of the 1st step | paragraph used in the 1st, 2nd and 3rd embodiment example of this invention. It is explanatory drawing of the array waveguide grating of the 2nd step | paragraph used in the 1st, 2nd and 3rd Example of this invention. It is explanatory drawing of the 3rd-stage arrayed-waveguide grating | lattice used in the 1st Example of this invention. It is a figure explaining the input-output characteristic of the array waveguide grating of the 3rd step | paragraph in the 1st Example of this invention. It is a block diagram of the 2nd Example of this invention. It is explanatory drawing of the 3rd-stage arrayed-waveguide grating | lattice used in the 2nd Example of this invention. It is a block diagram of the 3rd Example of this invention. It is explanatory drawing of the array waveguide grating of the 3rd step | paragraph used in the 3rd Example of this invention. It is explanatory drawing about the structure which implement | achieves the improvement of the 1st, 2nd and 3rd embodiment of this invention. It is a block diagram of the 4th Example of this invention. It is explanatory drawing of the 2nd stage arrayed-waveguide grating | lattice used by the 4th, 5th, and 6th embodiment example of this invention. It is explanatory drawing of the array waveguide grating | lattice of the 1st step | paragraph used in the 4th, 5th, and 6th embodiment example of this invention. It is explanatory drawing of the 3rd-stage arrayed-waveguide grating | lattice used in the 4th Example of this invention. It is a block diagram of the 5th Example of this invention. It is explanatory drawing of the 3rd-stage arrayed-waveguide grating | lattice used in the 5th Example of this invention. It is a block diagram of the 6th Embodiment of this invention. It is explanatory drawing of the 3rd-stage arrayed-waveguide grating | lattice used in the 6th Example of this invention.

Explanation of symbols

401 First array waveguide grating 402 Input waveguide of first array waveguide grating 403 to 406 Output waveguide of first array waveguide grating 407 to 410 Optical gate switch 411 Second array waveguide grating 412 415 Input waveguide of second array waveguide grating 416 to 419 Output waveguide of second array waveguide grating 420 to 423 Optical gate switch 424 Third array waveguide grating 425 to 429 Third array waveguide grating Input waveguide 430 to 434 output waveguide of third arrayed waveguide grating 435 2 × 1 optical converging circuit 436 output waveguide

Claims (5)

An optical frequency filter that selectively extracts only an optical signal having a specific optical frequency from among optical multiplexed signals composed of a plurality of optical frequencies,
A first arrayed waveguide grating having a plurality of output waveguides each having an optical gate switch for inputting an optical multiplexed signal having a plurality of optical frequencies;
A second arrayed waveguide grating for inputting an optical signal output from the first arrayed waveguide grating and having a plurality of output waveguides each having an optical gate switch;
E Bei a third arrayed waveguide grating for inputting an optical signal output from the second array waveguide grating,
When the first array waveguide grating has a higher resolution than the second array waveguide grating, the free spectrum range of the third array waveguide grating is the first array waveguide. It is configured to be wider by one channel interval than the free spectral range of the grating,
A characteristic optical frequency filter. An optical frequency filter that selectively extracts only an optical signal having a specific optical frequency from among optical multiplexed signals composed of a plurality of optical frequencies,
A first arrayed waveguide grating having a plurality of output waveguides each having an optical gate switch for inputting an optical multiplexed signal having a plurality of optical frequencies;
A second arrayed waveguide grating for inputting an optical signal output from the first arrayed waveguide grating and having a plurality of output waveguides each having an optical gate switch;
E Bei a third arrayed waveguide grating for inputting an optical signal output from the second array waveguide grating,
When the second array waveguide grating has a higher resolution than the first array waveguide grating, the free spectral range of the third array waveguide grating is the second array waveguide. It is configured to be wider by one channel interval than the free spectral range of the grating,
A characteristic optical frequency filter. An optical frequency filter that selectively extracts only an optical signal having a specific optical frequency from among optical multiplexed signals composed of a plurality of optical frequencies,
A first arrayed waveguide grating having a plurality of output waveguides each having an optical gate switch for inputting an optical multiplexed signal having a plurality of optical frequencies;
A second arrayed waveguide grating for inputting an optical signal output from the first arrayed waveguide grating and having a plurality of output waveguides each having an optical gate switch;
A third arrayed waveguide grating which receives target light signal output of said second arrayed waveguide grating,
As an input optical signal to the output of said second arrayed waveguide grating, and an optical distribution circuit you distribute inputs the optical signals to the third arrayed waveguide grating,
When the first array waveguide grating has a higher resolution than the second array waveguide grating, the free spectrum range of the third array waveguide grating is the first array waveguide. It is configured to be wider by one channel interval than the free spectral range of the grating,
A characteristic optical frequency filter. An optical frequency filter that selectively extracts only an optical signal having a specific optical frequency from among optical multiplexed signals composed of a plurality of optical frequencies,
A first arrayed waveguide grating having a plurality of output waveguides each having an optical gate switch for inputting an optical multiplexed signal having a plurality of optical frequencies;
A second arrayed waveguide grating for inputting an optical signal output from the first arrayed waveguide grating and having a plurality of output waveguides each having an optical gate switch;
A third arrayed waveguide grating which receives target light signal output of said second arrayed waveguide grating,
As an input optical signal to the output of said second arrayed waveguide grating, and an optical distribution circuit you distribute inputs the optical signals to the third arrayed waveguide grating,
When the second array waveguide grating has a higher resolution than the first array waveguide grating, the free spectral range of the third array waveguide grating is the second array waveguide. It is configured to be wider by one channel interval than the free spectral range of the grating,
A characteristic optical frequency filter. The optical frequency filter according to any one of claims 1 to 4,
Using a semiconductor optical amplifier as the optical gate switch,
A characteristic optical frequency filter.

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