CN100544236C - Device for generating low-jitter dual-wavelength ultrashort optical pulses - Google Patents

Abstract

A kind of generation device of low dithering dual wavelength ultrashort light pulse belongs to optical communication and ultrafast phenomena research field.It is characterized in that: utilize a temperature to control tuning gain switch F-P semiconductor laser as main laser; Adopt two dfb semiconductor lasers to provide light beam to go into as the external seed source to main laser, implementation pattern is selected output and the effectively shake of reduction light pulse in main laser; Utilize optical circulator and fiber grating to realize the output that separates of dual wavelength, thereby obtain low dithering dual wavelength ultrashort light pulse.The present invention has realized the low jitter of gain switch ultrashort light pulse and dual-wavelength tunable output simultaneously, have output stable, simple in structure, be easy to realization and advantage such as applied widely.

Description

Device for generating low-jitter dual-wavelength ultrashort optical pulses

technical field

The device for generating low-jitter dual-wavelength ultrashort optical pulses of the invention belongs to the field of optical communication and ultrafast phenomenon research.

Background technique

Using the gain switch (electrical modulation) method to generate semiconductor laser pulses has the advantages of simple structure, small size, low price, and continuously adjustable pulse repetition frequency. Therefore, gain switch semiconductor lasers are often used in the research of optical communication systems and ultrafast phenomena. as a laser pulse source. However, since this kind of optical pulse is established on the basis of spontaneous radiation in the laser cavity, the fluctuation of spontaneous radiation will cause the randomness of the generation time of the optical pulse, which will lead to the instantaneous change of the repetition frequency of the optical pulse, resulting in the time jitter of the pulse. . The time jitter of the optical pulse will directly affect the bit error rate of the optical communication system, and become a bottleneck restricting the development of optical communication to a higher speed.

Jitter will also limit other applications of ultrashort optical pulses. For example, in the electro-optical sampling system based on ultrashort optical pulses, the existence of jitter reduces the time resolution of the measurement system. In measurement, the presence of jitter will reduce the signal-to-noise ratio of the measurement system.

The time jitter of optical pulse can be reduced by optical injection method. The principle is to use the injected light to suppress the fluctuation of the number of photons in the establishment of the optical pulse caused by spontaneous radiation, thereby reducing the time jitter of the optical pulse. The current jitter reduction technology can be divided into self-seed injection technology and external light injection technology. The former requires precise adjustment of the round-trip time of the self-seed pulse in the external feedback cavity to make it equal to an integer multiple of the optical pulse period, which makes the repetition rate of the optical pulse cannot be achieved. Arbitrary adjustment limits its scope of application. The external light injection technology uses a wavelength-tunable monochromatic laser as a seed source, and the cost is relatively high. At present, the light pulse obtained after the two technologies reduce the jitter is a single wavelength.

However, multi-wavelength optical pulse sources are required in wavelength division multiplexing (WDM) and dense wavelength division multiplexing (DWDM) optical communication systems. The generation of multi-wavelength ultrashort optical pulses based on gain-switched F-P semiconductor lasers is becoming a research hotspot.

Contents of the invention

The purpose of the device for generating low-jitter dual-wavelength ultrashort optical pulses of the present invention is to realize a dual-wavelength ultrashort optical pulse source that can simultaneously generate low jitter, thereby disclosing a device that can achieve simple structure, stable output, and large side-mode suppression ratio. The technical solution of the low-jitter dual-wavelength ultrashort optical pulse generation device.

The device for generating low-jitter dual-wavelength ultrashort optical pulses of the present invention is characterized in that it is composed of a main laser system, an external seed source injection system and an optical pulse dual-wavelength separation system; the main laser system consists of a DC bias source (1), a signal source (2), T-type connector (3), F-P semiconductor laser (4) and temperature controller (5), the DC bias source (1) and signal source (2) are connected to the On the T-shaped connector (3), the F-P semiconductor laser (4) is welded on the T-shaped connector (3), and the output circuit of the temperature controller (5) is welded with the corresponding pins of the F-P semiconductor laser (4); the external seed The source injection system consists of an optical circulator (6) on the left, a fiber coupler (9), a fiber polarization controller on the left (10) and a fiber polarization controller on the right (11), and a DFB semiconductor laser with an optical isolator built in on the left (12) It consists of a DFB semiconductor laser (14) with an optical isolator built in on the right, a temperature controller (13) on the left and a temperature controller (15) on the right, and is controlled by the temperature controller (13) on the left and the temperature controller (15) on the right The operating temperature of the DFB semiconductor laser (12) with an optical isolator built in on the left and the DFB semiconductor laser (14) with an optical isolator built in on the right, adjust their output wavelengths close to the corresponding longitudinal modes of the F-P semiconductor laser (4), the left The optical circulator (6) and the fiber coupler (9) are connected by FC/PC fiber jumpers, the output ports of the left fiber polarization controller (10) and the right fiber polarization controller (11) are FC/PC, and the left fiber polarization One end of the controller (10) is connected to the fiber coupler (9), the other end is connected to the pigtail of the DFB semiconductor laser (12) with an optical isolator built in on the left, and one end of the right fiber polarization controller (11) is connected to the fiber coupler (9), the other end is connected to the DFB semiconductor laser (14) with an optical isolator built-in on the right, and the left temperature controller (13) and the right temperature controller (15) are respectively connected with the DFB semiconductor laser (12) with an optical isolator built-in in the left side ) and the DFB semiconductor laser (14) with built-in optical isolator on the right; the dual-wavelength optical pulse separation system is composed of the right optical circulator (7) and fiber grating (8), and the II end reflection of the right optical circulator (7) Either end of the optical fiber grating (8) is connected with an FC/PC fiber jumper; the main laser system, the external seed source injection system and the optical pulse dual-wavelength separation system are injected into the three-port left optical circulator (6 ) is connected in a 'T' shape, the fiber coupler (9) of the external seed source injection system is connected to the incident end of the optical circulator with the FC/PC connection flange, and the output pigtail of the F-P semiconductor laser (4) of the main laser system The reflective end of the optical circulator is connected through the FC/PC connection flange, and the incident end of the right optical circulator (7) of the dual-wavelength separation system is connected with the outgoing end of the optical circulator.

The external seed source injection system provides appropriate dual-wavelength optical seeds to the main laser system to achieve injection locking to obtain dual-wavelength mode selection output; at the same time, after the optical seeds are injected into the main laser system, the photon density at the oscillation threshold of the semiconductor laser 4 is provided. The excitation can effectively reduce the time jitter of the optical pulse; after the output optical pulse passes through the optical circulator 7 and the fiber grating 8, the dual wavelengths are separated, and finally low-jitter, dual-wavelength ultrashort optical pulses are generated.

The low-jitter dual-wavelength ultrashort optical pulse generation device proposed by the present invention has the following advantages compared with the reported ultrashort optical pulse generation device:

1. The seed source injection system does not require optical components such as EDFA and tunable filters.

2. Use temperature tuning technology to precisely control the wavelength of the injected light seeds, so that the locking mode selection efficiency is high, the operation is stable, and the obtained side mode suppression ratio is large.

3. By using the optical injection technology, the jitter reduction and dual-wavelength selective output of the gain-switched optical pulse are simultaneously realized.

4. The structure of the optical pulse dual-wavelength separation system is simple, and only one fiber grating and one optical circulator are used to effectively separate the two wavelengths.

In a word, the invention has stable output optical pulse, low jitter, high dual-wavelength side mode suppression ratio, simple structure and easy realization.

Description of drawings

Figure 1. Schematic diagram of the structure of Embodiment 1 of the device for generating low-jitter dual-wavelength ultrashort optical pulses of the present invention:

1: DC bias source, 2: Signal source, 3: T-type connector, 4: F-P semiconductor laser, 5: Temperature controller, 6: Left optical circulator, 7: Right optical circulator, 8: Fiber Bragg grating, 9: Fiber coupler, 10: Fiber polarization controller on the left, 11: Fiber polarization controller on the right, 12: DFB semiconductor laser with built-in optical isolator on the left, 13: Temperature controller on the left, 14: Built-in optical isolator on the right DFB semiconductor laser, 15: temperature controller on the right.

Figure 2. Structural schematic diagram of the second embodiment of the device for generating low-jitter dual-wavelength ultrashort optical pulses of the present invention: 1: DC bias source, 2: Signal source, 3: T-shaped connector, 4: F-P semiconductor laser, 5: Temperature controller, 6: fiber coupler, 7, 8, 10: fiber grating, 9: optical circulator.

Detailed ways

Embodiment 1: The DC bias source 1 is connected to the T-type connector 3 with a 10cm-long flexible cable with SMA (male) at one end. The bandwidth of the T-type connector 3 is 5 GHz, and the connection end is SMA (female); the signal source 2 Use a semi-rigid high-frequency cable with SMA (male) length of 6 cm at both ends to connect to the T-type connector 3; the F-P semiconductor laser 4 has a modulation bandwidth of 2.5 GHz, a central wavelength of 1550 nm, and a longitudinal mode interval of 1.0 nm. Built-in refrigerator, no The pins of the multi-mode semiconductor laser with built-in optical isolator are welded on the T-type connector 3; the temperature controller 5 is welded close to the bottom of the F-P semiconductor laser 4; the output pigtail of the F-P semiconductor laser 4 passes through FC/PC The connecting flange is connected to the II end of the optical circulator 6; the III end of the optical circulator 6 is connected to the I end of the optical circulator 7 by using a 0.5m long optical fiber jumper; the II end of the optical circulator 7 is connected by FC/PC The blue is connected with the I end of the fiber grating 8; the I end of the optical circulator 6 is connected with the fiber coupler 9 by using the FC/PC connection flange; The middle of the device 9 is connected to each other through optical fiber jumpers. The DFB semiconductor lasers 12 and 14 are quantum well single-mode semiconductor lasers with a central wavelength of 1550nm, a built-in refrigerator, and a built-in optical isolator; the temperature controllers 13 and 15 are respectively welded on the DFB on the semiconductor lasers 12,14.

The DC bias source 1 and the signal source 2 drive the F-P semiconductor laser 4 to generate a gain switch semiconductor laser pulse through the T-type connector 3, and the temperature controller 5 is used to control the working temperature of the F-P semiconductor laser 4; two DFB semiconductor lasers 12, 14 is used as the injection light seed source, using two temperature controllers 13, 15 to respectively control the operating temperature of the two, and adjust their output wavelengths to be close to the corresponding longitudinal modes of the main laser 4, and the fiber polarization controllers 10, 11 are used to adjust the injection The polarization state of the light seed, after the fiber coupler 9, the seed light is injected into the I end of the optical circulator 6; after the seed light is injected into the main laser 4, the two functions of wavelength selection and reduction of optical pulse jitter are realized simultaneously, and the optical circulator 6 Terminal III outputs ultra-short optical pulses with low jitter and dual wavelengths; the optical pulses are injected into terminal I of the optical circulator 7, and then enter a fiber grating 8 through terminal II of the optical circulator 7, and the fiber grating 8 pairs with one of the dual wavelengths The wavelength is reflected and transmitted to another wavelength. The transmitted wavelength exits from the II end of the fiber grating 8, and the reflected wavelength exits from the III end through the input of the II end of the optical circulator 7, and the dual wavelengths of the optical pulse are effectively separated; The output wavelength can be adjusted by changing the operating temperature of the seed source DFB semiconductor laser, so that different mode outputs of the main laser 4 can be selected, so as to realize the tunable output of dual wavelengths. The low-jitter dual-wavelength ultra-short optical pulse generating device has the advantages of stable output, large side-mode suppression ratio, small time jitter, independent of optical pulse repetition frequency, all-fiber optical path structure, and easy implementation.

Embodiment 2: The DC bias source 1 is connected to the T-type connector 3 by using an 8cm-long flexible cable with SMA (male) at one end. The bandwidth of the T-type connector 3 is 4.5 GHz, and the connection end is SMA (female); the signal source 2. Use a rigid high-frequency cable with SMA (male) length of 5 cm at both ends to connect to the T-type connector 3; F-P semiconductor laser 4 has a modulation bandwidth of 2.0 GHz, a central wavelength of 1555 nm, a longitudinal mode interval of 0.8 nm, a built-in refrigerator, and no The pins of the multi-mode semiconductor laser with built-in optical isolator are welded on the T-type connector 3; the temperature controller 5 is welded close to the bottom of the F-P semiconductor laser 4; the output pigtail of the F-P semiconductor laser 4 passes through FC/PC The connecting flange is connected to the fiber coupler 6; the other two ends of the fiber coupler 6 are respectively connected to the I end of the fiber grating 7 and the optical circulator 9; the fiber grating 7 is connected in series with the fiber grating 8 by using the FC/PC flange; The II end of the shaper 9 is connected to the I end of the fiber grating 10, and the fiber Bragg grating 10 is a fiber Bragg grating that reflects a certain longitudinal mode wavelength of the F-P semiconductor laser 4 and transmits another longitudinal mode wavelength.

The DC bias source 1 and the signal source 2 drive an F-P semiconductor laser 4 through a T-connector 3 to generate a gain-switched semiconductor laser pulse, and the temperature controller 5 is used to control the working temperature of the F-P semiconductor laser 4; the optical pulse passes through the fiber coupler After 6, it is divided into two outputs, one of which is incident on the fiber grating 7 and the fiber grating 8, and the two fiber gratings respectively reflect a certain two longitudinal mode wavelengths of the main laser 4, and the reflected light pulses of the two wavelengths become self-seeds The source is injected into the main laser 4 through the fiber coupler 6, so that the injection-locked selected wavelength output is realized in the main laser 4 and the time jitter of the optical pulse is reduced at the same time; the output dual-wavelength optical pulse passes through the II end of the optical circulator 9 Incident into a fiber grating 10, the fiber grating 10 reflects a certain wavelength in the dual wavelength and transmits the other wavelength, the transmitted wavelength exits from the II end of the fiber grating 10, and the reflected wavelength passes through the II end of the optical circulator 9 The terminal input exits from its III terminal, so that the dual wavelengths of the optical pulse are effectively separated. The low-jitter dual-wavelength ultra-short optical pulse generator has the advantages of simple structure, low time jitter, all-fiber optical path structure, and integration.

Claims (1)

1. A device for generating low-jitter dual-wavelength ultrashort optical pulses, characterized in that: it is composed of a main laser system, an external seed source injection system and an optical pulse dual-wavelength separation system; the main laser system consists of a DC bias source (1), Composed of signal source (2), T-type connector (3), F-P semiconductor laser (4) and temperature controller (5), DC bias source (1) and signal source (2) through a 5-10cm high-frequency cable Connected to the T-type connector (3), the F-P semiconductor laser (4) is welded on the T-type connector (3), and the output circuit of the temperature controller (5) is welded to the corresponding pins of the F-P semiconductor laser (4); The external seed source injection system consists of a left optical circulator (6), a fiber coupler (9), a left fiber polarization controller (10) and a right fiber polarization controller (11), a DFB semiconductor laser with a built-in optical isolator on the left ( 12) is composed of a DFB semiconductor laser (14) with an optical isolator built in on the right, a temperature controller (13) on the left and a temperature controller (15) on the right, using the temperature controller (13) on the left and the temperature controller (15) on the right Respectively control the operating temperature of the DFB semiconductor laser (12) with an optical isolator built in on the left and the DFB semiconductor laser (14) with an optical isolator built in on the right, and adjust their output wavelengths close to the corresponding longitudinal modes of the F-P semiconductor laser (4) , the left optical circulator (6) and the fiber coupler (9) are connected by FC/PC fiber jumpers, the output ports of the left fiber polarization controller (10) and the right fiber polarization controller (11) are FC/PC, the left One end of the fiber polarization controller (10) is connected to the fiber coupler (9), the other end is connected to the tail fiber of the DFB semiconductor laser (12) with an optical isolator built in on the left, and one end of the fiber polarization controller (11) on the right is connected to the optical fiber The coupler (9), the other end is connected to the DFB semiconductor laser (14) with an optical isolator built in on the right, the temperature controller (13) on the left and the temperature controller (15) on the right are respectively connected to the DFB semiconductor laser with an optical isolator built in on the left (12) is welded with the DFB semiconductor laser (14) that the right side has built-in optical isolator; The dual-wavelength optical pulse separation system is made up of right optical circulator (7) and fiber grating (8), and the II of right optical circulator (7) The end reflection end is connected to either end of the fiber grating (8) by FC/PC fiber jumper; the main laser system, the external seed source injection system and the optical pulse dual-wavelength separation system pass through the three-port left optical circulator in the external seed source injection system (6) According to the 'T' shape connection, the fiber coupler (9) of the external seed source injection system uses the FC/PC connection flange to connect the incident end of the optical circulator, and the output of the F-P semiconductor laser (4) of the main laser system The pigtail is connected to the reflective end of the optical circulator through the FC/PC connection flange, and the incident end of the right optical circulator (7) of the dual-wavelength separation system is connected to the outgoing end of the optical circulator.

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