Self-injection locking multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering and multi-linewidth laser generation method thereof

Abstract

The invention provides a self-injection locking multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering and a multi-linewidth laser generation method thereof. A working light source DFB laser is connected with a first port of a circulator, and a second port of the circulator is connected with an optical fiber resonant cavity through a coupler I; the optical fiber resonant cavity is connected with the output end B through a third port of the coupler II and a third port of the coupler III; a No.2 port of the coupler III is connected with an output end C through a phase modulator; a first port of the coupler III is connected with an attenuator through a Gaussian phase modulator, and the attenuator is connected with a working light source DFB laser through a fourth port and a first port of a circulator. Brillouin scattering in the optical fiber resonant cavity is connected with a second port of the circulator through the coupler I, and a third port of the circulator is connected with the output end A; the invention is used for solving the problem that a dual-frequency and multi-line-width laser can simultaneously meet light sources of different types of RMOGs, can effectively improve the versatility of the laser, and reduces the research and development cost of the optical gyroscope.

Description

Technical Field

[0001] The invention belongs to the field of optical gyroscopes, and in particular relates to a self-injection locked multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering and a multi-linewidth laser generation method thereof. Background Art

[0002] The resonant micro-optical gyroscope (RMOG) uses a resonant cavity that transmits light in a circular manner to enhance the Sagnac effect caused by the angular velocity of rotation. In theory, the same detection accuracy as that of a laser gyroscope can be obtained by using a shorter optical fiber or optical microcavity, which not only reduces the system volume but also reduces the influence of temperature drift. At the same time, each optical device inside the RMOG can be realized by an integrated optical method. With the continuous development and breakthroughs in micro-nano optical processing technology, RMOG has the potential to achieve large-scale low-cost manufacturing. Therefore, RMOG shows great potential in high precision, miniaturization and low cost, and has gradually become a research hotspot in the field of autonomous unmanned systems at home and abroad. However, the narrow linewidth tunable laser in the traditional RMOG has the disadvantages of large size, high cost and single use, and it is urgent to carry out research on new alternative light sources.

[0003] According to the type of laser used, RMOG can be divided into traditional RMOG driven by narrow linewidth laser and RMOG driven by broadband laser. In the traditional RMOG system driven by narrow linewidth laser, the coherence length of the laser with a certain linewidth will affect the coherence of the interference light output by the resonant cavity, causing the resonance peak to become wider, affecting the clarity of the resonant cavity. Therefore, in order to obtain better resonant cavity characteristics and frequency locking stability, a continuously tunable narrow linewidth laser is usually used as the light source. In the RMOG driven by broadband laser, the use of broadband light source can effectively reduce the backscattering noise caused by the multi-turn structure of the resonant cavity. At the same time, the use of multi-turn structure can also significantly reduce the relative intensity noise error generated when the broadband light source outputs RMOG. Therefore, different types of RMOG have different application requirements for factors such as the linewidth and stability of the laser.

[0004] With the continuous rise and development of various types of optical gyroscopes, lasers with a single linewidth and frequency have seriously increased the R&D cost of RMOG. At present, there is still a lack of a dual-frequency, multi-linewidth laser to simultaneously meet the light source of different types of RMOG. DFB lasers based on self-injection locking are one of the most promising ways to solve the above problems. Self-injection locking technology can effectively narrow the laser linewidth and stabilize the laser frequency. However, due to the complexity and sensitivity of the laser, additional linewidth narrowing and widening technologies need to be introduced to achieve linewidth regulation based on self-injection locking technology. Therefore, how to design a self-injection locked multi-linewidth laser for optical gyroscopes is an urgent problem to be solved. Summary of the invention

[0005] In view of this, the present invention aims to propose a self-injection locked multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering, which is used to solve the problem of using dual-frequency, multi-linewidth lasers to simultaneously meet the light source problems of different types of RMOGs, which can effectively improve the versatility of the laser and reduce the research and development cost of the optical gyroscope.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0007] A self-injection locked multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering, the laser comprising a working light source DFB laser 1, a circulator 2, a coupler I 3, a coupler II 4, a coupler III 5, a phase modulator 6, a Gaussian phase modulator 7, an attenuator 8 and a fiber resonant cavity 9;

[0008] The working light source DFB laser 1 is connected to port 1 of the circulator 2, and port 2 of the circulator 2 is connected to the optical fiber resonant cavity 9 through a coupler I 3;

[0009] The optical fiber resonant cavity 9 is connected to the output end B through the coupler II4 and the port No. 3 of the coupler III5;

[0010] Port No. 2 of the coupler III 5 is connected to the output terminal C through the phase modulator 6;

[0011] Port No. 1 of the coupler III 5 is connected to the attenuator 8 via the Gaussian phase modulator 7, and the attenuator 8 is connected to the working light source DFB laser 1 via the port No. 4 and the port No. 1 of the circulator 2;

[0012] The Brillouin scattering in the optical fiber resonant cavity 9 is connected to the port No. 2 of the circulator 2 through the coupler I3, and the port No. 3 of the circulator 2 is connected to the output end A.

[0013] Furthermore, there is no isolator inside the working light source DFB laser 1, the output wavelength of the working light source DFB laser 1 is 1550 nm, and the initial line width of the working light source DFB laser 1 is 1 MHz.

[0014] Furthermore, when the working light source DFB laser 1 is self-injection locked, the internal feedback light intensity is 0.01%.

[0015] Furthermore, the length of the optical fiber resonant cavity 9 is 2 meters.

[0016] Furthermore, the coupling coefficients of the coupler I3 and the coupler II4 are both 2 / 98.

[0017] Compared with the prior art, the self-injection locked multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering created by the present invention has the following advantages:

[0018] (1) Compared with expensive and bulky narrow-linewidth tunable lasers, the present invention uses a low-cost, small-sized DFB laser as an alternative light source through self-injection locking technology based on optical feedback, thereby achieving linewidth narrowing and frequency stabilization of the output laser.

[0019] (2) The present invention can be applied to both traditional RMOG driven by narrow-linewidth lasers and RMOG driven by wide-spectrum lasers. Experimental tests have demonstrated the effectiveness and versatility of the designed lasers.

[0020] Another purpose of the invention is to propose a multi-linewidth laser generation method based on Gaussian phase modulation and Brillouin scattering self-injection locked multi-linewidth laser, so as to solve the problem of dual-frequency, multi-linewidth lasers to simultaneously meet the light source of different types of RMOG, which can effectively improve the versatility of the laser and reduce the research and development cost of the optical gyroscope.

[0021] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0022] A method for generating a multi-linewidth laser of a self-injection-locked multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering, characterized in that the method for generating a multi-linewidth laser uses a self-injection-locked multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering as described above, and the method for generating a multi-linewidth laser comprises the following steps:

[0023] Step 1: The light wave of the single longitudinal mode laser output by the working light source DFB laser 1 enters the optical fiber resonant cavity 9 after passing through the circulator 2 and the coupler I 3. The light wave of the single longitudinal mode laser is circulated in the optical fiber resonant cavity 9 to generate interference of multiple beams and resonance.

[0024] Step 2: After the optical wave of the single longitudinal mode laser in the cavity is frequency-selected based on the optical fiber resonant cavity 9 in step 1, the optical wave of the single longitudinal mode laser is injected back into the working light source DFB laser 1 for self-injection locking, and the output light finally generates a narrow linewidth laser at the output end B;

[0025] Step 3: Based on the self-injection locking in step 2, the light wave of the single longitudinal mode laser at port 2 of coupler III 5 is spectrally broadened by the Gaussian phase modulator 7, and finally a wide-spectrum laser is generated at the output end C;

[0026] Step 4: Based on the self-injection locking in step 2, the internal excitation of the optical fiber resonant cavity 9 forms stimulated Brillouin scattering in the opposite direction, and finally generates a frequency-shifted extremely narrow linewidth laser at the output end A.

[0027] Furthermore, the step 2 is specifically as follows: after the optical fiber resonant cavity 9 performs frequency selection on the light wave of the single longitudinal mode laser in the cavity, the output light is output to the phase modulator 6 through the coupler II4 and the coupler III5 for initial phase delay adjustment. When the initial phase delay is closer to 0, the self-injection locking is more stable; the light wave of the single longitudinal mode laser after phase modulation is injected back into the working light source DFB laser 1 through the attenuator 8 and the circulator 2 for self-injection locking;

[0028] By changing the light field and carrier distribution structure inside the working light source DFB laser 1, the output characteristics are changed, and finally a narrow line width laser is generated at the output end B.

[0029] Furthermore, the step 3 is specifically that the light wave of the single longitudinal mode laser output from port No. 2 of coupler III5 is spectrally broadened through Gaussian phase modulator 7. Gaussian phase modulator 7 contains high-frequency stable Gaussian white noise. After signal amplification and gain matching, it enters Gaussian phase modulator 7 and modulates the light wave of the single longitudinal mode laser to achieve line width broadening of the laser, and finally generates a wide-spectrum laser at the output end C.

[0030] Furthermore, the step 4 is specifically as follows: the working light source DFB laser 1 outputs a single longitudinal mode laser light wave to the optical fiber resonant cavity 9 through the port No. 2 of the circulator 2 and the coupler I3. The single longitudinal mode laser light wave is excited inside the optical fiber resonant cavity 9 to form stimulated Brillouin scattering in the opposite direction. The stimulated Brillouin scattering has the characteristics of stimulated emission such as a small divergence angle and an extremely narrow linewidth, and the frequency pulling causes the stimulated Brillouin scattered light to produce a frequency shift phenomenon. The stimulated Brillouin scattering in the cavity passes through the coupler I3, the port No. 2 and the port No. 3 of the circulator 2 respectively, and finally generates a frequency-shifted extremely narrow linewidth laser at the output end A.

[0031] Furthermore, the output light width of the self-injection locked multi-linewidth laser can be adaptively adjusted by changing the initial phase delay, the fiber resonant cavity length and the Gaussian noise signal parameters.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] (1) The present invention excites high-coherence Brillouin scattering in a fiber ring cavity, and the generated Stokes signal can further narrow the line width on the basis of self-injection locking, while generating a Brillouin frequency shift.

[0034] (2) The present invention performs external Gaussian noise phase modulation at the output optical port, that is, loads a radio frequency voltage signal on the electro-optical phase modulator to change the phase characteristics of the signal light, thereby ultimately achieving the purpose of spectrum broadening. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0036] Figure 1 It is a schematic diagram of the structure of the present invention.

[0037] Figure 2 They are the phase noise measured curve and the wide spectrum line width measured curve of the present invention, wherein (a) is the phase noise measured curve of the present invention, and (b) is the wide spectrum line width measured curve of the present invention.

[0038] Figure 3 The graphs are the measured Allan variance curves of the laser of the present invention applied to the traditional RMOG driven by narrow-linewidth laser and the RMOG driven by broadband laser, wherein (a) is the measured Allan variance curve of the laser of the present invention applied to the traditional RMOG driven by narrow-linewidth laser, and (b) is the measured Allan variance curve of the laser of the present invention applied to the RMOG driven by broadband laser.

[0039] Description of reference numerals:

[0040] The working light source includes a DFB laser 1, a circulator 2, a coupler I 3, a coupler II 4, a coupler III 5, a phase modulator 6, a Gaussian phase modulator 7, an attenuator 8, and a fiber resonant cavity 9. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0042] In the following description, specific details such as specific system structures and technologies are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0043] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0044] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this application specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0045] The following is attached to this application specification Figure 1-2 , the technical solutions in the embodiments of the present application are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0046] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific implementation methods disclosed below.

[0047] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0048] Implementation Method 1

[0049] This embodiment provides a self-injection locked multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering, the laser includes a working light source DFB laser 1, a circulator 2, a coupler I 3, a coupler II 4, a coupler III 5, a phase modulator 6, a Gaussian phase modulator 7, an attenuator 8 and a fiber resonant cavity 9;

[0050] The working light source DFB laser 1 is connected to port 1 of the circulator 2, and port 2 of the circulator 2 is connected to the optical fiber resonant cavity 9 through a coupler I 3;

[0051] The optical fiber resonant cavity 9 is connected to the output end B through the coupler II4 and the port No. 3 of the coupler III5;

[0052] Port No. 2 of the coupler III 5 is connected to the output terminal C through the phase modulator 6;

[0053] Port No. 1 of the coupler III 5 is connected to the attenuator 8 via the Gaussian phase modulator 7, and the attenuator 8 is connected to the working light source DFB laser 1 via the port No. 4 and the port No. 1 of the circulator 2;

[0054] The Brillouin scattering in the optical fiber resonant cavity 9 is connected to the port No. 2 of the circulator 2 through the coupler I3, and the port No. 3 of the circulator 2 is connected to the output end A.

[0055] Furthermore, there is no isolator inside the working light source DFB laser 1, the output wavelength of the working light source DFB laser 1 is 1550 nm, and the initial line width of the working light source DFB laser 1 is 1 MHz.

[0056] Furthermore, when the working light source DFB laser 1 is self-injection locked, the internal feedback light intensity is 0.01%.

[0057] Furthermore, the length of the optical fiber resonant cavity 9 is 2 meters.

[0058] Furthermore, the coupling coefficients of the coupler I3 and the coupler II4 are both 2 / 98.

[0059] Specifically, the working light source DFB laser 1, circulator 2, coupler I3, coupler II4, coupler III5, phase modulator 6, Gaussian phase modulator 7, attenuator 8 and optical fiber resonant cavity 9 all use optical path elements with polarization-maintaining characteristics.

[0060] Combination Figure 3 The Allan variance measured curves of the laser of the present invention applied to the narrow line width laser driven traditional RMOG and the broadband laser driven RMOG are as follows: Figure 3 As shown in Figs. a and 3b, Allan variance analysis is performed on the laser frequency in the frequency-locked state within 1000s, and the zero bias stability under the integration time of 100s is 0.07° / s and 0.96° / h, respectively, reaching industrial and tactical performances, respectively. More importantly, the laser of the present invention reduces the cost and size of gyro testing and enhances the versatility of the laser.

[0061] Implementation Method 2

[0062] This embodiment provides a method for generating a multi-linewidth laser of a self-injection-locked multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering. The multi-linewidth laser generating method uses a self-injection-locked multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering as described in Embodiment 1. The multi-linewidth laser generating method includes the following steps:

[0063] Step 1: The light wave of the single longitudinal mode laser output by the working light source DFB laser 1 enters the optical fiber resonant cavity 9 after passing through the circulator 2 and the coupler I 3. The light wave of the single longitudinal mode laser is circulated in the optical fiber resonant cavity 9 to generate interference of multiple beams and resonance.

[0064] Step 2: After the optical wave of the single longitudinal mode laser in the cavity is frequency-selected based on the optical fiber resonant cavity 9 in step 1, the optical wave of the single longitudinal mode laser is injected back into the working light source DFB laser 1 for self-injection locking, and the output light finally generates a narrow linewidth laser at the output end B;

[0065] Step 3: Based on the self-injection locking in step 2, the light wave of the single longitudinal mode laser at port 2 of coupler III 5 is spectrally broadened by the Gaussian phase modulator 7, and finally a wide-spectrum laser is generated at the output end C;

[0066] Step 4: Based on the self-injection locking in step 2, the internal excitation of the optical fiber resonant cavity 9 forms stimulated Brillouin scattering in the opposite direction, and finally generates a frequency-shifted extremely narrow linewidth laser at the output end A.

[0067] Furthermore, the step 2 is specifically as follows: after the optical fiber resonant cavity 9 performs frequency selection on the light wave of the single longitudinal mode laser in the cavity, the output light is output to the phase modulator 6 through the coupler II4 and the coupler III5 for initial phase delay adjustment. When the initial phase delay is closer to 0, the self-injection locking is more stable; the light wave of the single longitudinal mode laser after phase modulation is injected back into the working light source DFB laser 1 through the attenuator 8 and the circulator 2 for self-injection locking;

[0068] By changing the light field and carrier distribution structure inside the working light source DFB laser 1, the output characteristics are changed, and finally a narrow line width laser is generated at the output end B.

[0069] Furthermore, the step 3 is specifically that the light wave output from port No. 2 of coupler III5 is spectrally broadened through Gaussian phase modulator 7. Gaussian phase modulator 7 contains high-frequency stable Gaussian white noise. After signal amplification and gain matching, it enters Gaussian phase modulator 7 and modulates the light wave of the single longitudinal mode laser to achieve line width broadening of the laser, and finally generates a wide-spectrum laser at the output end C.

[0070] Furthermore, the step 4 is specifically as follows: the working light source DFB laser 1 outputs a single longitudinal mode laser light wave to the optical fiber resonant cavity 9 through the port No. 2 of the circulator 2 and the coupler I3. The single longitudinal mode laser light wave is excited inside the optical fiber resonant cavity 9 to form stimulated Brillouin scattering in the opposite direction. The stimulated Brillouin scattering has the characteristics of stimulated emission such as a small divergence angle and an extremely narrow linewidth, and the frequency pulling causes the stimulated Brillouin scattered light to produce a frequency shift phenomenon. The stimulated Brillouin scattering in the cavity passes through the coupler I3, the port No. 2 and the port No. 3 of the circulator 2 respectively, and finally generates a frequency-shifted extremely narrow linewidth laser at the output end A.

[0071] Furthermore, the output light width of the self-injection locked multi-linewidth laser can be adaptively adjusted by changing the initial phase delay, the fiber resonant cavity length and the Gaussian noise signal parameters.

[0072] Specifically, when the laser is self-injected locked, when the laser driving current is adjusted so that the free-running laser frequency gradually approaches the resonant frequency from the low frequency on the left or the high frequency on the right, the laser frequency will suddenly increase or decrease at the turning point, and then jump to the stable frequency locking area and lock at the resonant frequency. Similarly, when the laser frequency gradually moves away from the resonant frequency due to the tuning current or external interference until it exceeds the locking range, the laser frequency will jump out of the locking area at the turning point, causing the self-injection locking to be lost. Therefore, the entire self-injection locking process is that the DFB laser output laser is transmitted through the transmission resonant cavity and then fed back to the laser, and the laser frequency is locked at the resonant frequency of the resonant cavity through self-injection locking, achieving the effect of frequency locking and line width narrowing. When the DFB laser is swept to the resonant frequency of the resonant cavity, the voltage of the oscilloscope will suddenly rise and immediately reach the self-injection locking state, the laser output frequency is locked at the resonant frequency, and the locking range reaches 20MHz, until the laser frequency jumps out of the resonant frequency to reach the unlocked state, and returns to the laser free frequency output.

[0073] The DFB laser locks its frequency to a single resonant mode through self-injection locking. When the current is adjusted, the laser frequency will jump to the adjacent resonant mode and continue to maintain frequency stability, and the frequency change is equal to a free spectrum range. The self-injection locked mode hopping of the present invention can achieve continuous tuning of the laser while maintaining frequency stability.

[0074] Combination Figure 2 The measured phase noise curve of the present invention is as follows: Figure 2 As shown in a, the phase noise of a DFB laser, a DFB laser based on self-injection locking, and a DFB laser combining Brillouin scattering and self-injection locking were measured using a laser noise measurement system. It can be seen that the phase noise of the DFB laser based on self-injection locking and the DFB laser combining Brillouin scattering and self-injection locking is more than 20dBc / Hz lower than that of the DFB laser in the entire frequency band, and the phase noise above 1MHz can be as low as -135dBc / Hz. In addition, the phase noise level of the Brillouin scattering laser based on self-injection locking is lower than the phase noise of the DFB laser based on self-injection locking, indicating that stimulated Brillouin scattering can further narrow the laser linewidth. The measured curve of the wide spectrum linewidth of the present invention is shown in FIG. Figure 2 As shown in Figure b, before broadening, the spectral energy is concentrated at the central wavelength. By adjusting the appropriate gain, the carrier of the spectrum is suppressed after broadening, and the energy is dispersed near the central wavelength to form a Gaussian-like spectrum. After broadening, the spectral linewidth from the output terminal C is 11 GHz, which proves the effectiveness of laser spectrum broadening based on Gaussian white noise phase modulation.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A self-injection locked multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering, characterized in that: The laser comprises a working light source DFB laser (1), a circulator (2), a coupler I (3), a coupler II (4), a coupler III (5), a phase modulator (6), a Gaussian phase modulator (7), an attenuator (8) and a fiber resonant cavity (9); The working light source DFB laser (1) is connected to port No. 1 of the circulator (2), and port No. 2 of the circulator (2) is connected to the optical fiber resonant cavity (9) via a coupler I (3); The optical fiber resonant cavity (9) is connected to the output end B through the port No. 3 of the coupler II (4) and the coupler III (5); Port No. 2 of the coupler III (5) is connected to the output terminal C via a phase modulator (6); Port No. 1 of the coupler III (5) is connected to an attenuator (8) via a Gaussian phase modulator (7), and the attenuator (8) is connected to a working light source DFB laser (1) via ports No. 4 and No. 1 of the circulator (2); The Brillouin scattering in the optical fiber resonant cavity (9) is connected to the No. 2 port of the circulator (2) through the coupler I (3), and the No. 3 port of the circulator (2) is connected to the output end A.

2. The self-injection locked multi-linewidth laser according to claim 1, characterized in that: There is no isolator inside the working light source DFB laser (1), the output wavelength of the working light source DFB laser (1) is 1550 nm, and the initial line width of the working light source DFB laser (1) is 1 MHz.

3. The self-injection locked multi-linewidth laser according to claim 1, characterized in that: When the working light source DFB laser (1) performs self-injection locking, the internal feedback light intensity is 0.01%.

4. The self-injection locked multi-linewidth laser according to claim 1, characterized in that: The optical fiber resonant cavity (9) has a cavity length of 2 meters.

5. The self-injection locked multi-linewidth laser according to claim 1, characterized in that: The coupling coefficients of the coupler I (3) and the coupler II (4) are both 2 / 98.

6. A method for generating multi-linewidth lasers based on self-injection locked multi-linewidth lasers using Gaussian phase modulation and Brillouin scattering, characterized in that: The multi-linewidth laser generation method uses a self-injection locked multi-linewidth laser based on Gaussian phase modulation and Brillouin scattering as described in any one of claims 1 to 6, and the multi-linewidth laser generation method comprises the following steps: Step 1: The light wave of the single longitudinal mode laser output by the working light source DFB laser (1) enters the optical fiber resonant cavity (9) after passing through the circulator (2) and the coupler I (3). The light wave of the single longitudinal mode laser is circulated in the optical fiber resonant cavity (9) to generate interference of multiple light beams and resonance phenomenon; Step 2: After the optical wave of the single longitudinal mode laser in the optical fiber resonant cavity (9) in step 1 is frequency-selected, the optical wave of the single longitudinal mode laser is injected back into the working light source DFB laser (1) for self-injection locking, and the output light finally generates a narrow line width laser at the output end B; Step 3: Based on the self-injection locking in step 2, the single longitudinal mode laser at port 2 of coupler III (5) is spectrally broadened through a Gaussian phase modulator (7), and finally a wide-spectrum laser is generated at the output end C; Step 4: Based on the self-injection locking in step 2, the internal excitation of the optical fiber resonant cavity (9) forms stimulated Brillouin scattering in the opposite direction, and finally generates a frequency-shifted extremely narrow linewidth laser at the output end A.

7. The method for generating multi-linewidth lasers of a self-injection locked multi-linewidth laser according to claim 6, characterized in that: Specifically, the step 2 comprises: after the optical fiber resonant cavity (9) performs frequency selection on the light wave of the single longitudinal mode laser in the cavity, the light wave of the output single longitudinal mode laser is output to the phase modulator (6) through the coupler II (4) and the coupler III (5) for initial phase delay adjustment. When the initial phase delay is closer to 0, the self-injection locking is more stable; the light wave of the single longitudinal mode laser after phase modulation is injected back into the working light source DFB laser (1) through the attenuator (8) and the circulator (2) for self-injection locking; By changing the light field and carrier distribution structure inside the working light source DFB laser (1), the output characteristics are changed, and finally a narrow line width laser is generated at the output end B.

8. The method for generating multi-linewidth lasers of a self-injection locked multi-linewidth laser according to claim 6, characterized in that: Specifically, the step 3 comprises: the light wave of the single longitudinal mode laser output from the port No. 2 of the coupler III (5) is spectrally broadened through a Gaussian phase modulator (7); the Gaussian phase modulator (7) contains high-frequency stable Gaussian white noise, which, after signal amplification and gain matching, enters the Gaussian phase modulator (7) and modulates the light wave of the single longitudinal mode laser, thereby achieving line width broadening of the laser, and finally generating a wide-spectrum laser at the output end C.

9. The method for generating multi-linewidth lasers of a self-injection locked multi-linewidth laser according to claim 6, characterized in that: Specifically, the step 4 comprises the following steps: the working light source DFB laser (1) outputs a single longitudinal mode laser light wave to the optical fiber resonant cavity (9) through the port No. 2 of the circulator (2) and the coupler I (3); the single longitudinal mode laser light wave is excited inside the optical fiber resonant cavity (9) to form stimulated Brillouin scattering in the opposite direction; the stimulated Brillouin scattering has the characteristics of stimulated emission such as a small divergence angle and an extremely narrow line width, and the frequency pulling causes the stimulated Brillouin scattered light to produce a frequency shift phenomenon; the stimulated Brillouin scattering in the cavity passes through the coupler I (3), the port No. 2 and the port No. 3 of the circulator (2) respectively, and finally produces a frequency-shifted extremely narrow line width laser at the output end A.

10. The method for generating multi-linewidth lasers of a self-injection locked multi-linewidth laser according to claim 6, characterized in that: The output light width of the self-injection locked multi-linewidth laser can be adaptively adjusted by changing the initial phase delay, the fiber resonant cavity length and the Gaussian noise signal parameters.

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