CN103384950A - Laser waveguide device - Google Patents

Abstract

The invention discloses a laser waveguide device, which comprises: a first semiconductor ring laser SRL (1), a second SRL (2), a third SRL (3); the 3 SRLs are respectively tangent with the two cutting grooves so as to be mutually independent; the device further comprises a first complementary waveguide arm (51), one end of the first complementary waveguide arm (51) being tangent and coupled to the third annular waveguide (31) in a clockwise direction; a second complementary waveguide arm (52), one end of the second complementary waveguide arm (52) being tangential and coupled to the third annular waveguide (31) in a counterclockwise direction; the other end of the first complementary waveguide arm (51) and the other end of the second complementary waveguide arm (52) are coupled into a waveguide. The laser waveguide device provided by the embodiment of the invention can realize quick and large-range tunability of output optical wavelength.

Description

Laser waveguide

technical field

The invention relates to the field of optical transmission, in particular to a laser waveguide device.

Background technique

In the existing optical transmission and optical switching technologies, it is often necessary to use tunable lasers (TunableLasers, TL), and the TL outputs the wavelength required by the transmitting end according to the control information. The demand for TL is concentrated on the inventory and backup of optical modules at network nodes.

With the continuous development of the Internet, the network traffic continues to rise, and the network transmission capacity also increases rapidly. However, the expansion of switching capacity based on large-scale electrical processing chips is difficult to achieve, resulting in the "electronic bottleneck" of serious mismatch between transmission and switching capacity. Optical switching itself has the advantages of large capacity and low power consumption. It can be divided into optical path switching, but the switching granularity in units of wavelength is too large, which limits its application in small business granular scenarios. Optical burst switching (Optical Burst Switching) , OBS) and Optical Packet Switching (Optical Packet Switching, OPS) represent the all-photonic wavelength switching technology is the development trend of optical switching network.

Fast Tunable Lasers (FTL) are required in OBS and OPS optical networks, and can be used at the transmitter, intermediate network nodes, and receivers.

In the tuning range of FTL, it is generally required to cover the entire wavelength band (such as the 32nm range of C-Band), while the electronically controlled change grating wavelength range of ordinary distributed Bragg reflector (Distributed Bragg Reflector, DBR) lasers is usually around 2-3nm. In order to solve this problem, the existing FTL sampling grating distributed Bragg reflector (Sampling Grating Distributed BraggReflector, SGDBR), modulated grating Y type (MG-Y) and digital supermode DBR (DS-DBR) adopt two groups of grating reflection modes A combined approach to achieve a wide range of tuning.

However, the existing above-mentioned three kinds of FTL all need to fabricate a superstructure DBR grating structure, because the process of superstructure DBR is complicated, which makes the fabrication cost of the whole chip high.

Contents of the invention

In view of the fact that the existing laser structure is too complicated and frequency selection is difficult, the embodiment of the present invention provides a laser waveguide device, which changes the injection current of three Semiconductor Ring Lasers (SRL) through independent current control, so that the inter-ring light The fields achieve spatial cross-coupling, which excites light with the desired wavelength. Fast and wide-range tunability of the output light wavelength is realized.

In a first aspect, an embodiment of the present invention provides a laser waveguide device, the device comprising:

a first semiconductor ring laser SRL comprising a first ring waveguide having a first ring length, said first ring waveguide being tangent to one side of a first slot having a width less than 5 microns;

A second SRL comprising a second ring waveguide having a second ring length, the second ring waveguide being tangent to the other side of the first slot, the second ring waveguide being tangent to one side of the second slot Tangentially, the width of the second cut is less than 5 microns;

a third SRL including a third ring waveguide having a first ring length, the third ring waveguide being tangent to the other side of the second slot;

a first complementary waveguide arm, one end of the first complementary waveguide arm is tangent to and coupled to the third ring waveguide in a clockwise direction;

a second complementary waveguide arm, one end of the second complementary waveguide arm is tangent to and coupled to the third ring waveguide in a counterclockwise direction;

The other end of the first complementary waveguide arm is coupled with the other end of the second complementary waveguide arm to form a waveguide.

In the first implementation manner of the first aspect, the second SRL (2) further includes a second electrode (20), configured to input a second injection current into the second ring waveguide (21), so as to tune the The refractive index of the second ring waveguide (21) is adjusted, and finally the light field generated by the second SRL is adjusted, so that the light fields between the three rings realize spatial interaction coupling, thereby lasing light with a required wavelength. Alternatively, the first SRL (1) further includes a first electrode (10), used for inputting a first injection current into the first ring waveguide (11), so as to tune the refraction of the first ring waveguide (11) rate; the third SRL (3) also includes a third electrode (30), which is used to input a third injection current into the third ring waveguide (31), so as to tune the refraction of the third ring waveguide (31) In this way, by injecting the first injection current and the third injection current, these two currents are usually equal, and the light fields generated by the first SRL and the third SRL can be finally adjusted, so that the light fields between the three rings realize spatial reciprocally coupled, thereby emitting light with the desired wavelength.

In the second implementation manner of the first aspect, the second SRL (2) further includes a second electrode (20) for inputting a second injection current into the second ring waveguide (21) to tune the The refractive index of the second ring waveguide (21); the first SRL (1) also includes a first electrode (10), which is used to input a first injection current into the first ring waveguide (11) to tune the The refractive index of the first ring waveguide (11); the third SRL (3) also includes a third electrode (30), which is used to input a third injection current into the third ring waveguide (31) to tune the The refractive index of the third ring waveguide (31). In this way, by injecting the first injection current, the second injection current and the third injection current, wherein the first injection current and the third injection current are generally equal, it is possible to finally adjust the first SRL, the second SRL and the third SRL. The optical field of the three rings enables the spatial interaction coupling of the optical fields between the three rings, so that the light with the desired wavelength is emitted.

Specifically, the laser waveguide device disclosed in the embodiment of the present invention includes, from bottom to top, an indium phosphide substrate (91), an N-type confinement layer (92), a quantum well active layer (93), a P-type confinement layer (94), three ring waveguides (95) and a P-type ohmic contact layer (96). Further, the depth of the first groove and the second groove reaches at least the N-type confinement layer (92), so that the quantum well active layer (93) is divided into three independent parts, In this way, the control currents in the three SRLs can be independently injected into each region, thereby adjusting the optical field generated by a single waveguide ring.

The laser waveguide device in the embodiment of the present invention has three SRLs. The injection currents of the three SRLs are changed through independent current control to generate three light fields. Since the FSRs of the two light fields are the same and different from the FSR of the third light field, Adjacent parts of the light field are coupled through spatial interaction to excite light with the desired wavelength. The emitted light is coupled out through two complementary waveguide arms. By controlling the injection current, the inter-ring light field realizes spatial interaction coupling, so that the output light wavelength can be tuned quickly and in a wide range.

Description of drawings

Fig. 1 is the schematic diagram of the laser waveguide device of the embodiment of the present invention;

2 is a schematic diagram of a longitudinal section of a conductor ring laser of an embodiment laser of the present invention;

3A is one of the schematic diagrams of the lasing spectrum of the laser waveguide device according to the embodiment of the present invention;

3B is the second schematic diagram of the lasing spectrum of the laser waveguide device according to the embodiment of the present invention.

Detailed ways

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

The laser waveguide device in the embodiment of the present invention includes three semiconductor ring lasers (SemiconductorRing Laser, SRL). The ring waveguides of adjacent SRLs respectively have a slot through the active layer, so that the active layers of each SRL are independent of each other. The injection currents of the three SRLs are varied by independent current control, resulting in three light fields, two of which have the same free spectral region FSR and a different FSR from the third light field. Among the three light fields, the adjacent parts of the light fields merge the respective resonant cavity modes through spatial interaction coupling, and finally excite light with the desired wavelength. The emitted light is coupled out through two complementary waveguide arms, and synthesized into one channel for output. In the embodiment of the present invention, the structural features of the three SRLs and the slots between them are used to control the injection current so that the optical field between the rings realizes spatial interaction coupling, thereby realizing fast and wide-ranging tunability of the output light wavelength. The slits in the embodiment of the present invention can realize weak coupling of heat between SRLs, and the mutual thermal crosstalk is small, so it has the advantages of large tuning range, fast switching, narrow line width, integration and simple process flow.

Fig. 1 is the schematic diagram of the laser waveguide device of the embodiment of the present invention, as shown in the figure, this embodiment specifically comprises: the first semiconductor ring laser (Semiconductor Ring Laser, SRL1, the second SRL2, the third SRL3, the first complementary waveguide arm 51 and the second complementary waveguide arm 52 .

The first SRL1 has a first ring waveguide 11 , the second SRL2 has a second ring waveguide 21 , and the third SRL3 has a third ring waveguide 31 . Both the first ring waveguide 11 and the third ring waveguide 31 have a first length, and the second ring waveguide 21 has a second length. The first length can be slightly larger than the second length, or slightly smaller than the second length, and the first length can also be the same as the second length.

The first ring waveguide 11 is tangent to one side of the first slot 41 , and the second ring waveguide 21 is tangent to the other side of the first slot 41 . The width of the first groove 41 is generally not more than 5 microns, preferably 2-3 microns. The second ring waveguide 21 is tangent to one side of the second slot 42 , and the third ring waveguide 31 is adjacent to and tangent to the other side of the second slot 42 . The width of the second groove 42 is generally not more than 5 microns, preferably 2-3 microns.

One end of the first complementary waveguide arm 51 is tangent to and coupled to the third ring waveguide 31 in the clockwise direction, and one end of the second complementary waveguide arm 52 is tangent to and coupled to the third ring waveguide 31 in the counterclockwise direction. The other end of the first complementary waveguide arm 51 is coupled with the other end of the second complementary waveguide arm 52 to form one waveguide.

The light field of the first SRL1 and the light field of the second SRL2 excite light with a desired wavelength through spatially interactive coupling, and the light emitted by the third SRL3 passes through the first complementary waveguide arm 51 and the second complementary waveguide arm 52 output.

2 is a schematic diagram of a longitudinal section of a conductor ring laser in an embodiment of the present invention. As shown in the figure, the material structure of a conductor ring laser is an indium phosphide (InP) substrate 91, an N-type (n+ ion-doped Miscellaneous) confinement layer 92 , GaAlInAs/InP quantum well active layer 93 , P-type (p+ ion doped) confinement layer 94 , three ring waveguides 95 and P-type ohmic contact layer 96 .

The first slot 41 and the second slot 42 are at least cut from the P-type ohmic contact layer 96 and the P-type confinement layer 94 to the N-type (n+ ion-doped) confinement layer 92, so that the injection control currents in the three SRLs can be independently Injected into each region of each SRL, the two slots can also realize thermal weak coupling between SRLs, reducing the influence of thermal crosstalk generated during the respective current tuning processes. The two laser spots are strictly limited in the quantum well active layer 93 .

As shown in Figure 1 again, the first SRL1 also includes a first electrode 10, the first electrode 10 can generate a first injection current, thereby generating a first optical field in the first ring waveguide 11; the optical frequency of the first ring waveguide 11 is The first optical frequency receives the first injection current, and tunes the refractive index of the first ring waveguide 11 to generate the first free spectral region FSR.

The second SRL2 also includes a second electrode 20, the second electrode 20 can generate a second injection current so as to generate a second optical field in the second ring waveguide 21; the optical frequency of the second ring waveguide 21 is the second optical frequency, receiving the second Injecting current, tuning the refractive index of the second ring waveguide 21 produces the second FSR.

The third SRL3 also includes a third electrode 30, the third electrode 30 can generate the same first injection current as the first electrode 30 so as to generate a third optical field in the third ring waveguide 31; the length of the third ring waveguide 31 is also the first length, the optical frequency is also the first optical frequency, receives the third injection current, usually the third injection current is the same as the first injection current, thus changing the refractive index of the third ring waveguide 31 to produce the same first injection current as the first ring waveguide 31 FSR.

The second loop length of the second ring waveguide 21 can be the same as the first loop length of the first ring waveguide 11 and the third ring waveguide 31 , and the second injection current of the second electrode 20 can be adjusted at this time. The second ring length of the second ring waveguide 21 may also be slightly greater than or slightly smaller than the first ring length. In this embodiment, the second length is slightly greater than the first length.

Two independent first SRL1 and second SRL2 are adjacent to each other through the first slot 41, so the active layers of SRL1 and SRL2 are independent of each other, and belong to thermal weak coupling, and the light fields of SRL1 and SRL2 pass through the first slot 41 Neighboring regions are reciprocally coupled. Two independent second SRL2 and third SRL3 are adjacent to each other through the second slit 42, so the active layers of SRL2 and SRL3 are independent of each other, and belong to thermal weak coupling, and the light fields of SRL2 and SRL3 pass through the second slit 42 Neighboring regions are reciprocally coupled.

3A is one of the schematic diagrams of the lasing spectrum of the laser waveguide device according to the embodiment of the present invention, and FIG. 3A is a schematic diagram of the independent lasing modes of SRL1 and SRL2.

According to the free spectral region FSR formula describing the frequency interval between the longitudinal modes of each laser: FSR=c/(n×L), where c represents the propagation speed of light in free space, which is 2.99792458×10 ⁸ m/s; n is The refractive index of the waveguide is related to the material of the waveguide; L is the ring length of the waveguide. Since the first ring length of the first ring waveguide 11 is smaller than that of the second ring waveguide 21, FSR1>FSR2.

When the two SRLs work independently without mutual coupling, as shown in the spectra of the SRL1 and SRL2 lasing modes shown in Figure 2A, the optical frequency of the lasing mode of SRL1 is F1, and the free spectral region is FSR1; the lasing mode of SRL2 is FSR1; The optical frequency of the radiation mode is F2, and the free spectral region is FSR2.

3B is the second schematic diagram of the lasing spectrum of the laser waveguide device according to the embodiment of the present invention, and FIG. 3B is a schematic diagram of the wavelength lasing mode after SRL1 and SRL2 are coupled.

When the optical fields of SRL1 and SRL2 are mutually coupled at adjacent waveguides, the resonant modes enter a common frequency-selective state, and only the lasing modes of the two SRLs are aligned, that is, the optical frequencies at the coincidence of the first FSR and the second FSR can be After being lased, other misaligned modes, that is, the optical frequency at the non-coincidence of the first FSR and the second FSR are greatly suppressed. In the figure, the common mode optical frequency F2 of SRL1 and SRL2 realizes lasing, and other mode the optical frequency is suppressed.

Because after the injection current changes, the refractive index of the waveguide changes under the action of the electro-optic effect, so when the second injection current of the second electrode 20 in SRL2 is tuned, or the first injection current of the first electrode 10 of SRL1 is tuned, the The refractive index of the second ring waveguide 21 in SRL2 or the first ring waveguide 11 in SRL1 changes. According to the formula FSR=c/(n×L), because n changes, FSR changes, resulting in a change in the pattern position of the co-alignment of SRL1 and SRL2, which is F2 alignment in Figure 2B.

Optionally, the second injection current of the second electrode 20 in SRL2 and the first injection current of the first electrode 10 of SRL1 can also be tuned at the same time to flexibly adjust the refractive index of the first ring waveguide 11 and the second ring waveguide 21 , so that the co-aligned mode position of SRL1 and SRL2 changes, and finally selects the required lasing light.

Optionally, when the second ring length of the second ring waveguide 21 can be the same as the first ring length of the first ring waveguide 11 and the third ring waveguide 31, according to the formula FSR=c/(n×L), FSR1= FSR2. At this time, the second injection current can be adjusted to change the refractive index n of the second ring waveguide 21 so that FSR1 is different from FSR2. Alternatively, the first injection current is adjusted to change the refractive index n of the first ring waveguide 11 so that FSR1 is different from FSR2.

If the second injection current is changed so that n of the second ring waveguide 21 decreases and FSR2 is increased, F1 can be aligned, then the lasing wave changes from F2 to F1, and the function of wavelength tuning is completed. Since the electro-optical tuning speed can reach ns level, the wavelength tuning time of the whole laser waveguide device can reach ns level.

The second optical field of the second ring waveguide 21 and the third optical field of the third ring waveguide 31 are coupled adjacent to the second slot 42, so that the laser light of the second ring waveguide 21 is coupled out of the third ring waveguide 31 . Because the ring length of the third ring waveguide 31 of SRL3 is the same as the length of the first ring waveguide 11 of SRL1, and the injection current output by the first electrode and the third electrode is also the same, which is the first injection current, so the first The FSR generated by the three-ring waveguide 31 is the same as the FSR generated by the first ring waveguide 11, which is the first FSR, so SRL3 and SRL1 belong to synchronous tuning, so the effect of SRL3 on the entire lasing mode (that is, optical frequency) is the same as that of SRL1 The contribution is the same, and the main function of SRL3 is to conveniently realize the light output in clockwise and counterclockwise directions. When analyzing the wavelength tuning performance, it is not necessary to consider the lasing mode of SRL3, but only the lasing modes of SRL1 and SRL2.

As shown in FIG. 1 , the laser waveguide device of the embodiment of the present invention further includes: a semiconductor optical amplifier 7 .

Therefore, with the increase or decrease of the first injection current or the second injection current of SRL1 or SRL2, due to the optical bistable phenomenon of SRL, the laser light coupled into SRL3 by SRL2 through the second slot will appear clockwise and reverse. The light of the hour hand.

The upper end of the third ring waveguide 31 of SRL3 is connected with the first complementary waveguide arm (Up arm) 51 for coupling out the clockwise laser on SRL3; the lower end of the third ring waveguide 31 is connected with the second complementary waveguide arm (Bottom arm) ) 52 phase connection, used to couple the counterclockwise laser output on SRL3. The output end of the first complementary waveguide arm 51 is coupled with the output end of the second complementary waveguide arm 52, combined into one waveguide to output laser light, and then connected to a semiconductor optical amplifier (SOA) 7, SOA7 can output laser light to the coupler 6 to perform magnification. The output laser is connected with the light collimating lens and the pigtail at the end of the waveguide.

In the optical transmission and switching network, Embodiment L of the present invention can be used as a transmitter light source for wavelengths and sub-wavelengths (burst/packet), and can also be used as a light source for transmitting uplink signals at the user end of an optical access network; It can be used as a local oscillator light source for a receiver of a coherent optical communication system.

The SRL in the embodiment of the present invention uses a closed ring waveguide as a resonant cavity, and does not require a cleavage surface or a grating to provide optical feedback, so it has a compact structure, simple process, high reliability, easy integration, and has tunable, wavelength conversion and optical dual steady state effect. The embodiment of the present invention utilizes the spatial coupling of three SRLs to realize the fast tunable laser function, and can obtain the characteristics of wide tuning range and fast switching at the same time.

In the embodiment of the present invention, the lengths of the first and third ring waveguides of the three SRLs are slightly different from the length of the second ring waveguide, and independent injection current control is used to change the refractive index of each SRL, thereby realizing the Vernier effect , to achieve a wide range of tunable functions, and fully considering the optical bistable characteristics of SRL, two complementary waveguide arms are used to realize the coupling output of laser and pigtail.

Professionals should further realize that the units and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the relationship between hardware and software Interchangeability. In the above description, the composition and steps of each example have been generally described according to their functions. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

The steps of the methods or algorithms described in connection with the embodiments disclosed herein may be implemented by hardware, software modules executed by a processor, or a combination of both. Software modules can be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other Any other known storage medium.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, within the spirit and principles of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims (5)

1. a laser waveguide device, is characterized in that, described laser waveguide device comprises:

The first semiconductor ring laser device SRL(1), comprise the first disc waveguide (11) with first annular length, described the first disc waveguide (11) is tangent with a side of the first grooving (41), and the width of described the first grooving (41) is less than 5 microns;

The 2nd SRL(2), comprise the second disc waveguide (21) with second annular length, described the second disc waveguide (21) is tangent with the opposite side of described the first grooving (41), described the second disc waveguide (21) is tangent with a side of the second grooving (42), and the width of described the second grooving (42) is less than 5 microns;

Three S's RL(3), comprise the 3rd disc waveguide (31) with first annular length, described the 3rd disc waveguide (31) is tangent with the opposite side of described the second grooving (42);

The first complementary waveguide arm (51), an end of the described first complementary waveguide arm (51) be and coupling tangent with described the 3rd disc waveguide (31) along clockwise direction;

The second complementary waveguide arm (52), an end of the described second complementary waveguide arm (52) be and coupling tangent with described the 3rd disc waveguide (31) in the counterclockwise direction;

The other end of the other end of the described first complementary waveguide arm (51) and the described second complementary waveguide arm (52) is coupled into one tunnel waveguide.

2. laser waveguide device according to claim 1 is characterized in that:

Described the 2nd SRL(2) also comprise the second electrode (20), be used for to described the second disc waveguide (21) input the second Injection Current, with the refractive index of tuning described the second disc waveguide (21).

3. laser waveguide device according to claim 1 and 2 is characterized in that:

A described SRL(1) also comprise the first electrode (10), be used for to described the first disc waveguide (11) input the first Injection Current, with the refractive index of tuning described the first disc waveguide (11);

Described Three S's RL(3) also comprise third electrode (30), be used for to described the 3rd disc waveguide (31) input the 3rd Injection Current, with the refractive index of tuning described the 3rd disc waveguide (31).

4. laser waveguide device according to claim 3, it is characterized in that, described laser waveguide device comprises from top to bottom successively: InP substrate (91), N-type limiting layer (92), mqw active layer (93), P type limiting layer (94), three disc waveguides (95) and P type ohmic contact layer (96).

5. laser waveguide device according to claim 4, is characterized in that, the degree of depth of described the first grooving and described the second grooving reaches described N-type limiting layer (92) at least, makes described mqw active layer (93) be divided into separate three.

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