High-power tunable single-frequency laser module

Abstract

The utility model provides a high-power tunable single-frequency laser module, which comprises an annular resonant cavity structure and a primary amplification structure, and is characterized in that the annular resonant cavity structure is used for outputting single-frequency seed light; the annular resonant cavity structure comprises a tunable optical fiber filter, a first optical fiber annular filter and a second optical fiber annular filter which are sequentially connected in the transmission direction of the single-frequency seed light, and the tunable optical fiber filter is used for adjusting the wavelength range of the single-frequency seed light; the first optical fiber ring filter is used for carrying out first filtering processing on the line width of the single-frequency seed light, and the second optical fiber ring filter is used for carrying out second filtering processing on the line width of the single-frequency seed light; the single-frequency seed light is filtered through the first optical fiber ring filter and the second optical fiber ring filter, the single-frequency seed light is amplified through the first-stage amplification structure, high-power output of the narrow-linewidth tunable single-frequency seed light is obtained, and the narrow-linewidth tunable single-frequency seed light source is wide in application prospect.

Description

Technical Field

[0001] The utility model relates to the technical field of optical fiber lasers, in particular to a high-power tunable single-frequency laser module. Background Art

[0002] Single-frequency fiber laser modules offer advantages such as good coherence, narrow linewidth, and low noise. They hold broad application prospects in laser communications, lidar, gravitational wave detection, optical frequency standards and clocks, and terahertz radiation, making them a hot research topic for researchers in the laser field. The broad spectrum characteristics of wavelength-tunable single-frequency fiber laser modules have made them popular in fields such as biomedicine, high-precision spectroscopy, and metrology. Despite significant progress and breakthroughs in the wavelength tuning range and laser linewidth of narrow-linewidth tunable single-frequency fiber laser modules, their output power, without an amplifier stage, is only tens of milliwatts, mostly sufficient for laboratory and research needs. High-power laser output and engineering applications remain significant limitations. The output power of laser modules is primarily limited by the input power of the fiber Fabry-Perot interference filter. To ensure output wavelength tunability, an amplifier must be designed to amplify the laser power output from the oscillator stage.

[0003] Therefore, there is an urgent need for a high-power tunable single-frequency laser module to solve the above technical problems. Utility Model Content

[0004] The purpose of the utility model is to provide a high-power tunable single-frequency laser module to improve the technical problem that the high-power tunable single-frequency laser module in the prior art is difficult to output high-power narrow-linewidth tunable single-frequency laser.

[0005] To solve the above technical problems, the utility model provides a high-power tunable single-frequency laser module, including a ring resonator structure and a first-stage amplification structure. The ring resonator structure is used to output single-frequency seed light. The ring resonator structure includes a tunable fiber filter, a first fiber ring filter, and a second fiber ring filter connected in sequence along the transmission direction of the single-frequency seed light.

[0006] Among them, the tunable optical fiber filter is used to adjust the wavelength range of the single-frequency seed light; the first optical fiber ring filter is used to perform a first filtering process on the linewidth of the single-frequency seed light, and the second optical fiber ring filter is used to perform a second filtering process on the linewidth of the single-frequency seed light.

[0007] Preferably, the ring resonator structure includes a first pump source, a ring resonant optical path structure and a first isolator, the input end of the ring resonant optical path structure is connected to the first pump source, the output end of the ring resonant optical path structure is connected to the input end of the first isolator, and the output end of the first isolator is connected to the first-stage amplification structure.

[0008] Preferably, the ring resonant optical path structure further includes a wavelength division multiplexer and a first gain optical fiber;

[0009] The Pass end of the wavelength division multiplexer is connected to the first pump source, the Common end of the wavelength division multiplexer is fused to the first end of the first gain fiber, and the Reflect end of the wavelength division multiplexer is connected to the second fiber ring filter.

[0010] Preferably, the ring resonant optical path structure includes a second isolator, the input end of the tunable fiber filter is fused with the second end of the first gain fiber, the output end of the tunable fiber filter is connected to the input end of the second isolator, and the output end of the second isolator is connected to the first fiber ring filter.

[0011] Preferably, the first optical fiber ring filter includes a first coupler, a first input end of the first coupler is connected to an output end of the second isolator, and a first output end of the first coupler is connected to the second optical fiber ring filter;

[0012] The second input end of the first coupler is connected to the second output end of the first coupler.

[0013] Preferably, the second optical fiber ring filter includes a second coupler, a third coupler and a saturable absorber, the first input end of the second coupler is connected to the first optical fiber ring filter, the first output end of the second coupler is connected to the input end of the third coupler, the second input end of the second coupler is fused to the second end of the saturable absorber, and the second output end of the second coupler is connected to the first isolator.

[0014] Preferably, the first output end of the third coupler is connected to the Reflect end of the wavelength division multiplexer, and the second output end of the third coupler is fused to the first end of the saturable absorber.

[0015] Preferably, the saturable absorber is an unpumped active optical fiber.

[0016] Preferably, the first coupler is a 3dB coupler, the second coupler is a 50 / 50 2*2 coupler, and the third coupler is a 20 / 80 1*2 coupler.

[0017] Preferably, the first-stage amplification structure includes a second pump source, a combiner, a second gain fiber and a third isolator, the first input end of the combiner is connected to the first isolator, the second input end of the combiner is connected to the second pump source, the output end of the combiner is fused to the first end of the second gain fiber, and the second end of the second gain fiber is fused to the third isolator.

[0018] The beneficial effects of the utility model are as follows: different from the prior art, the utility model provides a high-power tunable single-frequency laser module, including a ring resonator structure and a first-stage amplification structure, the ring resonator structure is used to output single-frequency seed light, the ring resonator structure includes a tunable optical fiber filter, a first optical fiber ring filter and a second optical fiber ring filter connected in sequence along the transmission direction of the single-frequency seed light, wherein the tunable optical fiber filter is used to adjust the wavelength range of the single-frequency seed light; the first optical fiber ring filter is used to perform a first filtering process on the linewidth of the single-frequency seed light, and the second optical fiber ring filter is used to perform a second filtering process on the linewidth of the single-frequency seed light; the utility model first adjusts the wavelength range of the single-frequency seed light through the tunable optical fiber filter, and then filters the single-frequency seed light through the first optical fiber ring filter and the second optical fiber ring filter respectively to further compress the linewidth of the single-frequency seed light, and finally amplifies the single-frequency seed light through the first-stage amplification structure to obtain a high-power output of narrow-linewidth tunable single-frequency seed light, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram showing the connection of a high-power tunable single-frequency laser module provided in an embodiment of the present invention;

[0020] In the figure: 100 - high-power tunable single-frequency laser module; 10 - ring resonator structure; 101 - first pump source; 102 - wavelength division multiplexer; 103 - first gain fiber; 104 - tunable fiber filter; 105 - second isolator; 106 - first fiber ring filter; 1061 - first coupler; 107 - second fiber ring filter; 1071 - second coupler; 1072 - third coupler; 1073 - saturable absorber; 108 - first isolator; 20 - first-stage amplifier structure; 201 - second pump source; 202 - combiner; 203 - second gain fiber; 204 - third isolator. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0022] The purpose of this utility model is to address the defects of the existing technology and provide a high-power tunable single-frequency laser module, which greatly compresses the linewidth range of the single-frequency seed light output by the ring resonator structure, and can optimize the noise figure of the output signal light while achieving gain of the seed signal light.

[0023] The technical solution of the present utility model will now be described with reference to specific embodiments.

[0024] See also Figure 1 The present invention provides a high-power tunable single-frequency laser module 100, comprising a ring resonator structure 10 and a first-stage amplification structure 20. The ring resonator structure 10 is used to output single-frequency seed light. The ring resonator structure 10 comprises a tunable fiber filter 104, a first fiber ring filter 106, and a second fiber ring filter 107, which are sequentially connected along the transmission direction of the single-frequency seed light.

[0025] Among them, the tunable optical fiber filter 104 is used to adjust the wavelength range of the single-frequency seed light; the first optical fiber ring filter 106 is used to perform a first filtering process on the linewidth of the single-frequency seed light, and the second optical fiber ring filter 107 is used to perform a second filtering process on the linewidth of the single-frequency seed light.

[0026] In the embodiment of the present invention, the ring resonator structure 10 is a common optical resonator structure, comprising a closed annular optical path through which light can circulate. The performance and characteristics of the ring resonator depend on factors such as its geometry, size, refractive index profile, and coupling method with an external waveguide. By adjusting the parameters of the annular optical path, different filtering functions can be achieved to compress the linewidth of the signal light.

[0027] In an embodiment of the present invention, the ring resonator cavity structure 10 includes a first pump source 101, a ring resonant optical path structure and a first isolator 108. The input end of the ring resonant optical path structure is connected to the first pump source 101, the output end of the ring resonant optical path structure is connected to the input end of the first isolator 108, and the output end of the first isolator 108 is connected to the first-stage amplification structure 20.

[0028] Specifically, the first pump source 101 is used as the pump source of the ring resonator structure 10 to provide pump light; wherein, the first pump source 101 is preferably a 976 pump laser module to provide 976nm pump light.

[0029] Specifically, the ring resonant optical path structure is used to form a closed ring optical path to filter the pump light emitted by the first pump source 101 .

[0030] Specifically, the first isolator 108 is used to isolate the reverse light input to the first-stage amplification structure 20, thereby preventing reflection and interference of the single-frequency seed light and ensuring the stability of the system.

[0031] In an embodiment of the present invention, the ring resonant optical path structure includes a wavelength division multiplexer 102 and a first gain fiber 103. The Pass end (transmission end) of the wavelength division multiplexer 102 is connected to the first pump source 101, the Common end (common end) of the wavelength division multiplexer 102 is fused to the first end of the first gain fiber 103, and the Reflect end (reflection end) of the wavelength division multiplexer 102 is connected to the second fiber ring filter 107.

[0032] Specifically, the wavelength division multiplexer 102 is a reflective wavelength division multiplexer 102 (Reflective Wavelength Division Multiplexer, abbreviated as R-WDM), which is a device used in optical communication systems. Its main principle is to use reflection and diffraction phenomena to achieve multiplexing and demultiplexing of optical signals of different wavelengths. The reflective wavelength division multiplexer 102 is usually composed of one or more gratings, reflectors or other optical elements. When optical signals of different wavelengths are incident on the reflective wavelength division multiplexer 102, they will be reflected and diffracted inside the device, so that the optical signals of different wavelengths are separated or multiplexed; in an embodiment of the present utility model, the wavelength division multiplexer 102 is used to couple the 976nm pump light and part of the single-frequency seed light output by the third coupler 1072 in the second optical fiber ring filter 107 into the first gain fiber 103.

[0033] Specifically, the first gain fiber 103 is used for signal amplification and providing gain. The first gain fiber 103 is preferably a 6 / 125 erbium-doped fiber with high absorption rate (core diameter of 6 μm, cladding diameter of 125 μm).

[0034] In an embodiment of the present invention, the ring resonant optical path structure further includes a tunable optical fiber filter 104 and a second isolator 105. The input end of the tunable optical fiber filter 104 is fused to the second end of the first gain optical fiber 103, the output end of the tunable optical fiber filter 104 is connected to the input end of the second isolator 105, and the output end of the second isolator 105 is connected to the first optical fiber ring filter 106.

[0035] Specifically, the tunable fiber filter 104 is a Fabry-Perot tunable filter (FPTF), which is generally composed of two parallel reflective surfaces forming an optical resonant cavity; its main function is to select or filter out light of a specific wavelength or wavelength range from the input optical signal, and can flexibly adjust the selected wavelength range as needed.

[0036] Preferably, the tunable optical fiber filter 104 is used to tune the wavelength of the single-frequency seed light transmitted through the first gain optical fiber 103 to 1520-1620 nm.

[0037] Specifically, the second isolator 105 is used to isolate the reverse light, so that the single-frequency seed light in the ring resonant optical path structure propagates in one direction.

[0038] In the embodiment of the present utility model, the ring resonant optical path structure further includes a first optical fiber ring filter 106 , wherein a first input end of a first coupler 1061 in the first optical fiber ring filter 106 is connected to an output end of the second isolator 105 , and a first output end of the first coupler 1061 is connected to a second optical fiber ring filter 107 ;

[0039] The second input end of the first coupler 1061 is connected to the second output end of the first coupler 1061 .

[0040] Specifically, since the second input end of the first coupler 1061 is connected to the second output end of the first coupler 1061, the first fiber ring filter 106 has a first small ring optical path. This design can increase the free spectral range (FSR). The increase in FSR can more effectively separate or select light in a specific wavelength range, improve the selectivity and performance of filtering, achieve a filtering effect, and further achieve compression of the linewidth of the single-frequency seed light.

[0041] Preferably, the first coupler 1061 is a 3dB coupler.

[0042] In the embodiment of the present invention, the second optical fiber ring filter 107 includes a second coupler 1071, a third coupler 1072, and a saturable absorber 1073. The first input end of the second coupler 1071 is connected to the first optical fiber ring filter 106, the first output end of the second coupler 1071 is connected to the input end of the third coupler 1072, the second input end of the second coupler 1071 is fused to the second end of the saturable absorber 1073, and the second output end of the second coupler 1071 is connected to the first isolator 108.

[0043] Preferably, the first output end of the third coupler 1072 is connected to the Reflect end of the wavelength division multiplexer 102 , and the second output end of the third coupler 1072 is fused to the first end of the saturable absorber 1073 .

[0044] Specifically, the second coupler 1071, the third coupler 1072, and the saturable absorber 1073 in the second optical fiber ring filter 107 form a second small ring optical path, which can filter light of a specific wavelength, allowing it to pass or block it, thereby further compressing the linewidth of the single-frequency seed light. The working principle of the second optical fiber ring filter 107 is based on the interference and coupling effects of light. When the optical signal enters the second small ring optical path, due to the optical path difference and coupling between different optical paths, the light of a specific wavelength will be enhanced or attenuated, thereby realizing the filtering function.

[0045] Preferably, the second coupler 1071 is a 50 / 50 2*2 coupler, and the third coupler 1072 is a 20 / 80 1*2 coupler; the saturable absorber 1073 is an unpumped active fiber, which is one of quartz-doped fiber, phosphate-doped fiber, germanate-doped fiber, tellurate-doped fiber, and fluoride fiber.

[0046] In the embodiment of the present invention, the first-stage amplification structure 20 includes a second pump source 201, a combiner 202, a second gain fiber 203, and a third isolator 204. The first input end of the combiner 202 is connected to the first isolator 108, the second input end of the combiner 202 is connected to the second pump source 201, the output end of the combiner 202 is fused to the first end of the second gain fiber 203, and the second end of the second gain fiber 203 is fused to the third isolator 204.

[0047] Specifically, the second pump source 201 is a 940 nm pump laser module, which is used to provide 940 nm pump light.

[0048] Specifically, the beam combiner 202 is used to couple the 940 nm pump light and the single-frequency seed light output by the ring resonator structure 10 into the second gain fiber 203 .

[0049] Specifically, the second gain fiber 203 is used for signal amplification and providing gain. The second gain fiber 203 is preferably a 10 / 125 erbium-doped fiber with high absorption rate (core diameter of 10 μm, cladding diameter of 125 μm).

[0050] Specifically, the third isolator 204 is used to isolate the reverse light, so that the optical signal in the first-stage amplification structure 20 propagates in one direction.

[0051] Since the existing ring cavity is a traveling-wave cavity, the use of a ring cavity structure can suppress the spatial hole burning effect. Since the ring cavity itself has a longer cavity length than a linear cavity, it can achieve a higher-power laser output. At the same time, in order to obtain a narrow-linewidth single-frequency laser output, it is often difficult to achieve using a single-structure linear cavity or ring cavity structure. Therefore, the present invention designs a composite cavity structure based on the existing ring cavity, that is, a new ring resonant cavity structure 10 is designed by using a tunable fiber filter 104, a first fiber ring filter 106 having a first small ring optical path, and a second fiber ring filter 107 having a second small ring optical path. This greatly increases the free spectral range, can more effectively separate or select light within a specific wavelength range, improves the selectivity and performance of the filter, and achieves a filtering effect. A saturable absorber 1073 is used for further filtering to obtain a narrow-linewidth single-frequency seed light.

[0052] This structure uses a tunable filter to achieve wavelength tuning between 1520 and 1620 nm. To further increase the power of the laser module, a master oscillator power amplifier (MOPA) is used to further amplify the single-frequency seed light, achieving a tunable laser with an extremely narrow linewidth while maintaining high output power. Furthermore, the high-power tunable single-frequency laser module 100 provided by this utility model has a simple structure, is easy to integrate, and can be mass-produced.

[0053] Compared with the existing technology, the present invention has the following advantages:

[0054] First, the utility model can achieve high-power output of tunable single-frequency laser;

[0055] Second, the present invention uses a special ring resonator structure 10 to obtain a laser with an extremely narrow linewidth;

[0056] Third, the high-power tunable single-frequency laser module 100 provided by the present invention has a simple design, a compact structure, a small size, and is easy to integrate.

[0057] In summary, different from the prior art, the present invention provides a high-power tunable single-frequency laser module 100, including a ring resonator structure 10 and a first-stage amplification structure 20, the ring resonator structure 10 is used to output single-frequency seed light, the ring resonator structure 10 includes a tunable fiber filter 104, a first fiber ring filter 106 and a second fiber ring filter 107 connected in sequence along the transmission direction of the single-frequency seed light, wherein the tunable fiber filter 104 is used to adjust the wavelength range of the single-frequency seed light; the first fiber ring filter 106 is used to adjust the wavelength range of the single-frequency seed light; The linewidth of the seed light is filtered for the first time, and the second optical fiber ring filter 107 is used to filter the linewidth of the single-frequency seed light for the second time. The utility model first adjusts the wavelength range of the single-frequency seed light through the tunable optical fiber filter 104, and then filters the single-frequency seed light through the first optical fiber ring filter 106 and the second optical fiber ring filter 107 respectively to further compress the linewidth of the single-frequency seed light. Finally, the single-frequency seed light is amplified through the first-stage amplification structure 20 to obtain a high-power output of a narrow-linewidth tunable single-frequency seed light, which has broad application prospects.

[0058] It should be noted that the above embodiments all belong to the same utility model concept, and the description of each embodiment has its own focus. For any details not described in individual embodiments, reference may be made to the description in other embodiments.

[0059] The above embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.

Claims

1. A high-power tunable single-frequency laser module, characterized in that: The invention comprises a ring resonator structure and a first-stage amplification structure, wherein the ring resonator structure is used to output a single-frequency seed light, and the ring resonator structure comprises a tunable optical fiber filter, a first optical fiber ring filter, and a second optical fiber ring filter connected in sequence along the transmission direction of the single-frequency seed light; The tunable optical fiber filter is used to adjust the wavelength range of the single-frequency seed light; the first optical fiber ring filter is used to perform a first filtering process on the line width of the single-frequency seed light, and the second optical fiber ring filter is used to perform a second filtering process on the line width of the single-frequency seed light.

2. The high-power tunable single-frequency laser module according to claim 1, characterized in that: The ring resonator structure includes a first pump source, a ring resonant optical path structure, and a first isolator. The input end of the ring resonant optical path structure is connected to the first pump source, the output end of the ring resonant optical path structure is connected to the input end of the first isolator, and the output end of the first isolator is connected to the first-stage amplification structure.

3. The high-power tunable single-frequency laser module according to claim 2, characterized in that: The ring resonant optical path structure includes a wavelength division multiplexer and a first gain optical fiber; The Pass end of the wavelength division multiplexer is connected to the first pump source, the Common end of the wavelength division multiplexer is fused to the first end of the first gain fiber, and the Reflect end of the wavelength division multiplexer is connected to the second fiber ring filter.

4. The high-power tunable single-frequency laser module according to claim 3, characterized in that: The ring resonant optical path structure also includes a second isolator. The input end of the tunable optical fiber filter is fused to the second end of the first gain optical fiber. The output end of the tunable optical fiber filter is connected to the input end of the second isolator. The output end of the second isolator is connected to the first optical fiber ring filter.

5. The high-power tunable single-frequency laser module according to claim 4, characterized in that: The first optical fiber ring filter includes a first coupler, a first input end of the first coupler is connected to an output end of the second isolator, and a first output end of the first coupler is connected to the second optical fiber ring filter; The second input end of the first coupler is connected to the second output end of the first coupler.

6. The high-power tunable single-frequency laser module according to claim 5, characterized in that: The second optical fiber ring filter includes a second coupler, a third coupler, and a saturable absorber. The first input end of the second coupler is connected to the first optical fiber ring filter, the first output end of the second coupler is connected to the input end of the third coupler, the second input end of the second coupler is fused to the second end of the saturable absorber, and the second output end of the second coupler is connected to the first isolator.

7. The high-power tunable single-frequency laser module according to claim 6, characterized in that: The first output end of the third coupler is connected to the Reflect end of the wavelength division multiplexer, and the second output end of the third coupler is fused to the first end of the saturable absorber.

8. The high-power tunable single-frequency laser module according to claim 6, characterized in that: The saturable absorber is an unpumped active optical fiber.

9. The high-power tunable single-frequency laser module according to claim 6, characterized in that: The first coupler is a 3dB coupler, the second coupler is a 50 / 50 2*2 coupler, and the third coupler is a 20 / 80 1*2 coupler.

10. The high-power tunable single-frequency laser module according to claim 2, characterized in that: The first-stage amplification structure includes a second pump source, a beam combiner, a second gain fiber, and a third isolator. The first input end of the beam combiner is connected to the first isolator, the second input end of the beam combiner is connected to the second pump source, the output end of the beam combiner is fused to the first end of the second gain fiber, and the second end of the second gain fiber is fused to the third isolator.

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