A power stabilization system for frequency-doubled lasers

Abstract

The application discloses a frequency-doubled laser power stabilizing system, comprising a seed light source, a first polarization-maintaining 12-fiber coupler, a first semiconductor pump source, a first polarization-maintaining combiner, a first polarization-maintaining doped optical fiber, a second semiconductor pump source, a second polarization-maintaining combiner, a second polarization-maintaining doped optical fiber, a polarization-maintaining 21-fiber coupler, a periodical lithium niobate waveguide, a temperature control system, a second polarization-maintaining 12-fiber coupler and a photoelectric detector. After the seed laser is amplified by two laser amplifiers, the seed laser is converted into a frequency-doubled laser by a temperature-controlled frequency-doubling crystal, and a part of the frequency-doubled laser is collected by the photoelectric detector for feedback. On one hand, the feedback is fed back to the second semiconductor pump source for adjusting the power of the laser amplification, and on the other hand, the feedback is fed back to a frequency-doubling temperature control circuit for adjusting the power of the frequency-doubled output, so that the closed-loop stability of the laser power is realized. The application improves the output power stability of the frequency-doubled laser and is suitable for high-precision application scenarios.

Description

Technical Field

[0001] This invention relates to the field of optical fiber and laser technology, and in particular to a power stabilization system for a frequency-doubled laser. Background Technology

[0002] High-power lasers combined with frequency conversion technology using periodically polarized nonlinear crystals are a key means of achieving visible and ultraviolet light output. By converting infrared laser light into short-wavelength visible or ultraviolet light, this technology is widely used in medical, scientific research, and industrial fields, such as high-precision surgery, optical experiments, and precision machining. With advancements in laser technology and quasi-phase-matching technology, the efficiency and stability of frequency-doubled lasers have improved, but the stability of output power still faces challenges.

[0003] Laser power fluctuations are influenced by various factors, including internal component aging, environmental changes, and noise interference. Especially in high-precision equipment such as magnetometers and gyroscopes, power instability can severely impact system performance. Power fluctuations in frequency-doubled lasers primarily stem from instabilities during laser power amplification and frequency doubling. Therefore, dynamic adjustment is necessary to achieve stable power output. Current common solutions include active feedback control, the use of highly stable nonlinear crystal materials, and optimized laser cavity design, but technical bottlenecks remain. Improving the power stability of frequency-doubled lasers is a critical issue that urgently needs to be addressed in this field and is of great significance for high-precision applications. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a power stabilization system for a frequency-doubled laser. This system achieves high-power frequency-doubled laser output by performing two-way power amplification and laser frequency conversion on a low-power seed light. By monitoring the output laser power, the system provides feedback to control the power of the pump laser in the secondary path, thereby adjusting the output power during the amplification process. Simultaneously, it feeds back the temperature to the temperature control system, regulating the frequency doubling process of the periodic lithium niobate waveguide, thus achieving power stabilization of the frequency-doubled laser.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a frequency doubling laser power stabilization system, comprising a seed light source, a first polarization maintaining laser, and a second polarization maintaining laser. 2 fiber couplers, first semiconductor pump source, first polarization-maintaining combiner, first polarization-maintaining doped fiber, second semiconductor pump source, second polarization-maintaining combiner, second polarization-maintaining doped fiber, polarization-maintaining 2 1. Fiber optic coupler, periodic lithium niobate waveguide, temperature control system, second polarization maintaining 1 2. Fiber optic couplers and photodetectors;

[0006] The connections between the various parts are as follows:

[0007] Seed light source and first polarization maintenance 1 2. The first end of the fiber coupler is fused together, and the first polarization maintaining 1 The second end of the fiber coupler is fused to the first end of the first polarization-maintaining combiner; the second end of the first polarization-maintaining combiner is fused to one end of the first semiconductor pump source; the third end of the first polarization-maintaining combiner is fused to one end of the first polarization-maintaining doped fiber; and the other end of the first polarization-maintaining doped fiber is fused to the first polarization-maintaining doped fiber. 1. The first end of the fiber coupler is fused together; the first polarization maintaining 1 The third end of the 2nd fiber coupler is fused to the first end of the second polarization-maintaining combiner; the second end of the second polarization-maintaining combiner is fused to one end of the second semiconductor pump source; the third end of the second polarization-maintaining combiner is fused to one end of the second polarization-maintaining doped fiber; and the other end of the second polarization-maintaining doped fiber is fused to the polarization-maintaining 2nd fiber. 1. The second end of the fiber optic coupler is fused together; polarization maintenance 2. The third end of the fiber optic coupler is fused to one end of a periodic lithium niobate waveguide, which is placed inside the temperature control system. The other end of the periodic lithium niobate waveguide is connected to the second polarization-maintaining... 2. The first end of the fiber coupler is fused together, and the second end is polarization maintained. 2. The second end of the fiber optic coupler is connected to a photodetector. The output signal of the photodetector is used to control the second semiconductor pump source and the temperature control system. The second polarization maintaining 1 The third end of the fiber coupler serves as the output port of the frequency-doubled laser.

[0008] Compared with the prior art, the present invention has significant advantages and beneficial effects, specifically reflected in the following aspects:

[0009] This invention achieves high-power frequency-doubled laser output by performing two-path power amplification and laser frequency conversion on low-power seed light. The main amplification optical path is a saturated amplification process, which mainly realizes the power amplification of the laser, while the secondary amplification optical path works in the linear amplification region, ensuring that the small output pump signal has better adjustment capability for the amplified fundamental frequency light.

[0010] This invention utilizes a photodetector to obtain the output frequency-doubled laser power. On one hand, it is used to control the power of the pump laser in the secondary path, thereby adjusting the output power of the amplification process. On the other hand, it is fed back to the temperature control system to adjust the frequency doubling process of the periodic lithium niobate waveguide, thereby achieving power stability of the frequency-doubled laser. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a frequency-doubled laser power stabilization system according to an embodiment of the present invention;

[0012] Figure 2 This is a system control block diagram according to an embodiment of the present invention;

[0013] Reference numerals in the figures: 1, seed light source; 2, first polarization-maintaining 1×2 fiber coupler; 3, first semiconductor pump source; 4, first polarization-maintaining combiner; 5, first polarization-maintaining doped fiber; 6, second semiconductor pump source; 7, second polarization-maintaining combiner; 8, second polarization-maintaining doped fiber; 9, polarization-maintaining 2×1 fiber coupler; 10, periodic lithium niobate waveguide; 11, temperature control system; 12, second polarization-maintaining 1×2 fiber coupler; 13, photodetector. Detailed Implementation

[0014] To make the objectives and technical solutions of this application clearer, the present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention, but should not be used to limit the scope of protection of the present invention.

[0015] In the description of this invention, the use of terms such as "first," "second," and "third" is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features or the order of the technical features.

[0016] like Figure 1 As shown, this embodiment provides a frequency-doubled laser power stabilization system. This frequency-doubled laser power stabilization system includes the following components: a seed light source 1, and a first polarization-maintaining system 1. 2. Fiber optic coupler; 2. First semiconductor pump source; 3. First polarization-maintaining combiner; 4. First polarization-maintaining doped fiber; 5. Second semiconductor pump source; 6. Second polarization-maintaining combiner; 7. Second polarization-maintaining doped fiber; 8. Polarization-maintaining 2 1. Fiber optic coupler; 9. Periodic lithium niobate waveguide; 10. Temperature control system; 11. Second polarization maintaining element. 2. Fiber optic coupler 12 and photodetector 13.

[0017] The connections between the various components are as follows:

[0018] Seed light source 1 and first polarization maintaining 1 2. The first end of the fiber coupler 2 is fused together, and the first polarization maintaining 1 is... 2. The second end of fiber coupler 2 is fused to the first end of the first polarization-maintaining combiner 4. The second end of the first polarization-maintaining combiner 4 is fused to one end of the first semiconductor pump source 3. The third end of the first polarization-maintaining combiner 4 is fused to one end of the first polarization-maintaining doped fiber 5. The other end of the first polarization-maintaining doped fiber 5 is fused to the first polarization-maintaining doped fiber 2. 1. The first end of the fiber coupler 9 is fused together; the first polarization maintaining 1 The third end of fiber coupler 2 is fused to the first end of the second polarization-maintaining combiner 7, the second end of the second polarization-maintaining combiner 7 is fused to one end of the second semiconductor pump source 6, the third end of the second polarization-maintaining combiner 7 is fused to one end of the second polarization-maintaining doped fiber 8, and the other end of the second polarization-maintaining doped fiber 8 is fused to the first end of the second polarization-maintaining doped fiber 2. 1. The second end of the fiber coupler 9 is fused together; polarization maintaining 2 The third end of the fiber optic coupler 9 is fused to one end of the periodic lithium niobate waveguide 10, which is placed inside the temperature control system 11. The other end of the periodic lithium niobate waveguide 10 is connected to the second polarization maintaining system 1. 2. The first end of the fiber coupler 12 is fused together, and the second polarization maintaining 1 The second end of the fiber optic coupler 12 is connected to the photodetector 13. The output signal of the photodetector 13 is used to control the second semiconductor pump source 6 and the temperature control system 11, and the second polarization maintaining system 1. The third end of the fiber coupler 12 serves as the output port of the frequency-doubled laser.

[0019] Seed light source 1, first polarization maintenance 1 2. Fiber optic coupler; 2. First semiconductor pump source; 3. First polarization-maintaining combiner; 4. First polarization-maintaining doped fiber; 5. Second semiconductor pump source; 6. Second polarization-maintaining combiner; 7. Second polarization-maintaining doped fiber; 8. Polarization-maintaining 2 1. Fiber optic coupler; 9. Periodic lithium niobate waveguide; 10. Second polarization maintaining element; 1 Two fiber couplers and two other fiber couplers together form the optical path structure of the frequency doubling laser.

[0020] The following detailed explanation of the above-mentioned frequency-doubled laser power stabilization method and system, with reference to specific embodiments, is provided.

[0021] In one embodiment, the seed light source generates a low-power fundamental frequency laser, which is then amplified and converted to achieve frequency-doubled laser output.

[0022] The first semiconductor pump source 3, the first polarization-maintaining combiner 4, and the first polarization-maintaining doped fiber 5 form the main amplification optical path, while the second semiconductor pump source 6, the second polarization-maintaining combiner 7, and the second polarization-maintaining doped fiber 8 form the secondary amplification optical path.

[0023] The first semiconductor pump source 3 is a 940nm high-power (10W) multimode pump source, and the first polarization-maintaining doped fiber 5 is an erbium-ytterbium co-doped fiber with high absorption of 940nm pump light, with a length of 2m. The main amplification optical path works in saturated pump state and is mainly used for laser power enhancement.

[0024] The second semiconductor pump source 6 is a 940nm low-power (1W) single-mode pump source. The second polarization-maintaining doped fiber 8 is a 0.5m long erbium-ytterbium co-doped fiber with high absorption of 940nm pump light. The secondary amplification optical path operates in the linear region and is mainly used for power adjustment during laser amplification.

[0025] The periodic lithium niobate waveguide 10 is a quasi-phase-matched nonlinear frequency-doubled crystal used to convert fundamental frequency laser into frequency-doubled laser.

[0026] The temperature control system 11 includes a thermoelectric cooling component and a corresponding temperature control circuit, which is used to precisely control the temperature of the periodic lithium niobate waveguide 10. The temperature control accuracy is preferably ±1mK, maintaining quasi-phase matching conditions to ensure the stability of the frequency doubling process.

[0027] The photodetector 13 is a photodiode used to monitor the frequency-doubled laser power in real time and output feedback signals to control the working state of the second semiconductor pump source 6 and the temperature control system 11, thereby realizing closed-loop control of the amplification process of the secondary amplifier and the periodic lithium niobate waveguide frequency doubling process.

[0028] First bias protection 1 The splitting ratio of the third end and the second end of the fiber coupler 2 is preferably 10:90, and the second polarization maintaining 1 The splitting ratio of the third end and the second end of the fiber coupler 12 is preferably 99:1.

[0029] In one embodiment, the seed light source is a 1540nm narrow-linewidth single-frequency low-power laser (40mW), the first semiconductor pump source 3 is a 10W power output multimode 940nm laser pump source, the second semiconductor pump source 6 is a 1W power output single-mode 940nm laser pump source, and the first polarization-maintaining 1... The second port of fiber coupler 2 is the 90% output port, and the first polarization maintaining port 1... The third port of fiber coupler 2 is the 10% output port. The first end of the first polarization-maintaining combiner 4 and the second polarization-maintaining combiner 7 is the input signal port, the second end is the pump input port, and the third end is the output signal port. The first polarization-maintaining doped fiber 5 and the second polarization-maintaining doped fiber 8 are the same type of commercially available high-erbium ion-doped erbium fiber, with a peak absorption of 55dB / m at 1530nm. The length of the first polarization-maintaining doped fiber 5 is 2m, and the length of the second polarization-maintaining doped fiber 8 is 0.5m. The periodic lithium niobate waveguide realizes the conversion of the fundamental frequency light with a wavelength of 1540nm into a frequency-doubled laser of 770nm. The temperature control system has an adjustment accuracy of ±1mK and an adjustment range of 20~100℃. The second polarization-maintaining fiber 1... The third end of fiber coupler 12 is the 99% output port, which serves as the laser output port for this system. The second end is the 1% output port, used to detect the stability of the output power. The photodetector has a detection wavelength range of 800~1700nm.

[0030] In this embodiment, a high-power frequency-doubled laser output is achieved by performing two-way power amplification and laser frequency conversion on the low-power seed light. The main amplification optical path is a saturated amplification process, which mainly realizes the power amplification of the laser, while the secondary amplification optical path works in the linear amplification region to ensure that the small output pump signal has better adjustment capability for the amplified fundamental frequency light.

[0031] In this embodiment, the low-power seed light is amplified in two ways, and the final output power is approximately 4W of single-frequency narrow-linewidth fundamental frequency light.

[0032] This embodiment utilizes a periodic lithium niobate waveguide to perform frequency conversion on amplified fundamental frequency light. The periodic lithium niobate waveguide can withstand a power of up to 5W. The input fundamental frequency light is 1540nm, the wavelength of the frequency-doubled laser is 770nm, and the temperature adjustment range is 30~70℃, achieving a frequency-doubled light power output of more than 2W.

[0033] In this embodiment, the temperature control system includes a thermoelectric cooling component and a corresponding temperature control circuit, which is used to precisely control the temperature of the periodic lithium niobate waveguide. The temperature control accuracy is preferably ±1mK, which can realize fine control of the frequency doubling stage by adjusting the temperature within a small range, thereby improving the power control accuracy of the frequency doubling stage.

[0034] This embodiment utilizes a photodetector to obtain the output frequency-doubled laser power. On one hand, it is used to control the power of the pump laser in the secondary path, thereby adjusting the output power of the amplification process. On the other hand, it is fed back to the temperature control system to adjust the frequency doubling process of the periodic lithium niobate waveguide, thereby achieving power stability of the frequency-doubled laser.

[0035] Figure 2 The photodetector pair is shown Figure 1 The diagram shows the overall control block diagram of the circuit, where the frequency multiplier is a periodic lithium niobate waveguide 10, and the beam splitter is a second polarization maintaining 1. 2. Fiber optic coupler 12, the laser driver in the secondary amplifier is the internal drive circuit of the second semiconductor pump source 6, and the temperature transmitter is an internal submodule of the temperature control system 11, which is part of the temperature control system 11.

[0036] The contents of this invention not described in detail are existing technologies known to those skilled in the art.

[0037] The above embodiments are provided merely for the purpose of describing the present invention and are not intended to limit the scope of the invention. The scope of the invention is defined by the appended claims. Various equivalent substitutions and modifications made without departing from the spirit and principles of the invention should be covered within the scope of the invention.

Claims

1. A power stabilization system for a frequency-doubled laser, characterized in that, It includes a seed light source (1), a first polarization-maintaining 1×2 fiber coupler (2), a first semiconductor pump source (3), a first polarization-maintaining combiner (4), a first polarization-maintaining doped fiber (5), a second semiconductor pump source (6), a second polarization-maintaining combiner (7), a second polarization-maintaining doped fiber (8), a polarization-maintaining 2×1 fiber coupler (9), a periodic lithium niobate waveguide (10), a temperature control system (11), a second polarization-maintaining 1×2 fiber coupler (12), and a photodetector (13). The connections between the various parts are as follows: The seed light source (1) is fused to the first end of the first polarization-maintaining 1×2 fiber coupler (2), the second end of the first polarization-maintaining 1×2 fiber coupler (2) is fused to the first end of the first polarization-maintaining combiner (4), the second end of the first polarization-maintaining combiner (4) is fused to one end of the first semiconductor pump source (3), the third end of the first polarization-maintaining combiner (4) is fused to one end of the first polarization-maintaining doped fiber (5), and the other end of the first polarization-maintaining doped fiber (5) is fused to the first end of the polarization-maintaining 2×1 fiber coupler (9). The third end of the first polarization-maintaining 1×2 fiber coupler (2) is fused to the first end of the second polarization-maintaining combiner (7), the second end of the second polarization-maintaining combiner (7) is fused to one end of the second semiconductor pump source (6), the third end of the second polarization-maintaining combiner (7) is fused to one end of the second polarization-maintaining doped fiber (8), and the other end of the second polarization-maintaining doped fiber (8) is fused to the second end of the polarization-maintaining 2×1 fiber coupler (9). The third end of the polarization-maintaining 2×1 fiber coupler (9) is fused to one end of the periodic lithium niobate waveguide (10), which is placed inside the temperature control system (11). The other end of the periodic lithium niobate waveguide (10) is fused to the first end of the second polarization-maintaining 1×2 fiber coupler (12), and the second end of the second polarization-maintaining 1×2 fiber coupler (12) is connected to the photodetector (13). The output signal of the photodetector (13) is used to control the second semiconductor pump source (6) and the temperature control system (11). The third end of the second polarization-maintaining 1×2 fiber coupler (12) serves as the output port of the frequency-doubled laser.

2. The power stabilization system for a frequency-doubled laser according to claim 1, characterized in that, The seed light source (1), the first polarization-maintaining 1×2 fiber coupler (2), the first semiconductor pump source (3), the first polarization-maintaining combiner (4), the first polarization-maintaining doped fiber (5), the second semiconductor pump source (6), the second polarization-maintaining combiner (7), the second polarization-maintaining doped fiber (8), the polarization-maintaining 2×1 fiber coupler (9), the periodic lithium niobate waveguide (10), and the second polarization-maintaining 1×2 fiber coupler (12) together constitute the optical path structure of the frequency-doubled laser.

3. The power stabilization system for a frequency-doubled laser according to claim 1, characterized in that, The seed light source generates a low-power fundamental frequency laser.

4. The power stabilization system for a frequency-doubled laser according to claim 1, characterized in that, The first semiconductor pump source (3), the first polarization-maintaining combiner (4), and the first polarization-maintaining doped fiber (5) serve as the main amplification optical path, while the second semiconductor pump source (6), the second polarization-maintaining combiner (7), and the second polarization-maintaining doped fiber (8) serve as the secondary amplification optical path.

5. The power stabilization system for a frequency-doubled laser according to claim 4, characterized in that, The first semiconductor pump source (3) is a 940nm high-power multimode pump source, and the first polarization-maintaining doped fiber (5) is an erbium-ytterbium co-doped fiber that highly absorbs the 940nm pump light. The fiber is 2m long and the main amplification optical path works in a saturated pump state, mainly used for laser power enhancement.

6. The power stabilization system for a frequency-doubled laser according to claim 4, characterized in that, The second semiconductor pump source (6) is a 940nm low-power single-mode pump source, and the second polarization-maintaining doped fiber (8) is an erbium-ytterbium co-doped fiber that highly absorbs the 940nm pump light. The length is 0.5m. The secondary amplification optical path works in the linear region and is used for power adjustment during the laser amplification process.

7. The power stabilization system for a frequency-doubled laser according to claim 1, characterized in that, The periodic lithium niobate waveguide (10) is a quasi-phase-matched nonlinear frequency-doubled crystal used to convert fundamental frequency laser into frequency-doubled laser.

8. The power stabilization system for a frequency-doubled laser according to claim 1, characterized in that, The temperature control system (11) includes a thermoelectric cooling component and a corresponding temperature control circuit, which is used to precisely control the temperature of the periodic lithium niobate waveguide (10), with a temperature control accuracy of ±1mK, and maintain quasi-phase matching conditions.

9. The power stabilization system for a frequency-doubled laser according to claim 1, characterized in that, The photodetector (13) is a photodiode used to monitor the frequency doubling laser power in real time and output feedback signals to control the working status of the second semiconductor pump source (6) and the temperature control system (11).

10. A power stabilization system for a frequency-doubled laser according to claim 1, characterized in that, The splitting ratio of the third end and the second end of the first polarization-maintaining 1×2 fiber coupler (2) is 10:90, and the splitting ratio of the third end and the second end of the second polarization-maintaining 1×2 fiber coupler (12) is 99:1.

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