Power stabilizing system of frequency doubling laser

Abstract

The invention discloses a frequency doubling laser power stabilizing system. Comprising a seed light source, a first polarization-maintaining 1 # imgabs0 # 2 optical fiber coupler, a first semiconductor pumping source, a first polarization-maintaining beam combiner, a first polarization-maintaining doped optical fiber, a second semiconductor pumping source, a second polarization-maintaining beam combiner, a second polarization-maintaining doped optical fiber, a polarization-maintaining 2 # imgabs1 # 1 optical fiber coupler, a periodic lithium niobate waveguide, a temperature control system, a second polarization-maintaining 1 # imgabs2 # 2 optical fiber coupler and a photoelectric detector. After being amplified by two paths of lasers, the seed laser is converted into frequency-doubled laser through a temperature-controlled frequency-doubling crystal, a part of frequency-doubled laser is acquired and is collected by a photoelectric detector for feedback, on one hand, the frequency-doubled laser is fed back to a second semiconductor pumping source for adjusting the laser amplification power, and on the other hand, the frequency-doubled laser is fed back to a frequency-doubled temperature control circuit for adjusting the laser amplification power. The method is used for adjusting frequency-doubled output power and realizing closed-loop stability of laser power. The output power stability of the frequency-doubled laser is improved, and the frequency-doubled laser is suitable for high-precision application scenes.

Description

Technical Field

[0001] The invention relates to the field of optical fiber and laser technology, and in particular to a frequency doubling laser power stabilization system. Background Art

[0002] High-power lasers combined with frequency conversion technology of periodically polarized nonlinear crystals are the key means to achieve visible light and ultraviolet light output. By converting infrared lasers 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 the advancement of laser technology and quasi-phase matching technology, the efficiency and stability of frequency-doubled lasers have been improved, but the stability of output power still faces challenges.

[0003] Laser power fluctuations are affected by many factors, including internal component aging, environmental changes, and noise interference. Especially in high-precision equipment such as magnetometers and gyroscopes, unstable power will seriously affect system performance. The power fluctuations of frequency-doubled lasers are mainly due to the instability in the laser power amplification and frequency-doubled conversion process. Therefore, dynamic adjustment is required to achieve stable power output. At present, common solutions include active feedback control, the use of high-stability nonlinear crystal materials, and optimized laser cavity design, but there are still technical bottlenecks. Improving the power stability of frequency-doubled lasers is a key issue that needs to be solved in this field, and it is of great significance for high-precision applications. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a frequency doubling laser power stabilization system, which realizes the output of high-power frequency doubling laser by performing two-way power amplification and laser frequency conversion on low-power seed light, and monitors the power of the output laser. On the one hand, it feeds back to control the power of the secondary pump laser, thereby adjusting the output power of the amplification process, and on the other hand, it feeds back to the temperature of the temperature control system to adjust the frequency doubling process of the periodic lithium niobate waveguide, thereby achieving power stabilization of the frequency doubling laser.

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

[0006] The connection relationship between each part is:

[0007] Seed light source and first polarization maintaining 1 2 The first end of the fiber coupler is fused, and the first polarization maintaining The second end of the optical fiber coupler 2 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 optical fiber, and the other end of the first polarization-maintaining doped optical fiber is fused to the polarization-maintaining 2 1 The first end of the optical fiber coupler is fused; the first polarization maintaining 1 The third end of the optical fiber coupler 2 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 optical fiber, and the other end of the second polarization-maintaining doped optical fiber is fused to the polarization-maintaining 2 1. The second end of the fiber coupler is fused; polarization maintenance 2 The third end of the optical fiber coupler is fused to one end of the periodic lithium niobate waveguide, the periodic lithium niobate waveguide is placed inside the temperature control system, and the other end of the periodic lithium niobate waveguide is fused to the second polarization maintaining 2 The first end of the fiber coupler is fused, and the second end is polarization-maintaining 1 2 The second end of the optical fiber coupler is connected to a photodetector, and the output signal of the photodetector is used to control the second semiconductor pump source and the temperature control system. 2 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, which are specifically embodied in the following aspects:

[0009] The present invention performs two-way power amplification and laser frequency conversion on low-power seed light to achieve the output of high-power frequency-doubled laser. The main amplification optical path is a saturation 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 tiny output pump signal has better regulation ability on the amplified fundamental frequency light.

[0010] The present invention utilizes a photoelectric detector to obtain the output frequency-doubled laser power. On the one hand, it is used to feedback control the power of the secondary pump laser, thereby adjusting the output power of the amplification process. On the other hand, it is fed back to the temperature of the temperature control system to adjust the frequency-doubled process of the periodic lithium niobate waveguide, thereby achieving power stability of the frequency-doubled laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural schematic diagram of a frequency-doubling laser power stabilization system in an embodiment of the present invention;

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

[0013] Figure numerals: 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 DESCRIPTION

[0014] In order to make the purpose and technical solution of this application clearer, the present invention is further described below in conjunction with the accompanying drawings and specific implementations. It should be understood that the specific embodiments described herein are only used to explain the present invention, but should not be used to limit the scope of protection of the present invention.

[0015] In the description of the present invention, if there is a description of first, second, and third, it is only used to distinguish the technical features and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0016] like Figure 1 As shown, this embodiment provides a frequency-doubled laser power stabilization system. The frequency-doubled laser power stabilization system includes the following components: a seed light source 1, a first polarization-maintaining light source 1 2 Fiber 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 1 Fiber coupler 9, periodic lithium niobate waveguide 10, temperature control system 11, second polarization maintaining 1 2 Fiber coupler 12 and photodetector 13.

[0017] The connection relationship between each component is as follows:

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

[0019] Seed light source 1, first polarization maintaining source 1 2 Fiber 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 1 Fiber coupler 9, periodic lithium niobate waveguide 10, second polarization maintaining 1 2 The optical fiber coupler 12 together constitutes the optical path structure of the frequency-doubled laser.

[0020] The above-mentioned frequency-doubled laser power stabilization method and system are explained in detail below in conjunction with specific embodiments.

[0021] In one embodiment, the seed light source generates low-power fundamental frequency laser, and the output of frequency-doubled laser is achieved through power amplification and laser frequency conversion.

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

[0023] The first semiconductor pump source 3 is a 940nm high-power (10W) multi-mode pump source, 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, and the main amplification optical path works in a saturated pumping state, 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 an erbium-ytterbium co-doped fiber with high absorption of 940nm pump light, with a length of 0.5m, and the secondary amplification optical path works in the linear region, which is mainly used for power regulation during laser amplification.

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

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

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

[0028] First polarization 1 The splitting ratio between the third end and the second end of the optical fiber coupler 2 is preferably 10:90, and the second polarization-maintaining The splitting ratio between the third end and the second end of the optical 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 (power is 40mW), the first semiconductor pump source 3 is a 10W power output multi-mode 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 2 The second port of the optical fiber coupler 2 is the 90% output port, and the first polarization maintaining port 1 The third port of the optical fiber coupler 2 is a 10% output port. The first ends of the first polarization-maintaining combiner 4 and the second polarization-maintaining combiner 7 are input signal ports, the second ends are pump input ports, and the third ends are output signal ports. The first polarization-maintaining doped optical fiber 5 and the second polarization-maintaining doped optical fiber 8 are the same commercial high erbium ion-doped erbium-doped optical fibers. The peak absorption at 1530nm reaches 55dB / m. The length of the first polarization-maintaining doped optical fiber 5 is 2m, and the length of the second polarization-maintaining doped optical fiber 8 is 0.5m. The periodic lithium niobate waveguide realizes the conversion of the fundamental frequency light with a wavelength of 1540nm into the frequency-doubled laser of 770nm. The adjustment accuracy of the temperature control system is ±1mK, and the adjustment range is 20~100℃. The second polarization-maintaining doped optical fiber 1 is 2m long, and the second polarization-maintaining doped optical fiber 8 is 0.5m long. The third end of the fiber coupler 12 is a 99% output port, which is used as the laser output port of the system, and the second end is a 1% output port for detecting the stability of the output power. The detection wavelength range of the photodetector is 800~1700nm.

[0030] In this embodiment, two-way power amplification and laser frequency conversion are performed on the low-power seed light to realize the output of high-power frequency-doubled laser. The main amplification optical path is a saturation 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 tiny output pump signal has better regulation ability on the amplified fundamental frequency light.

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

[0032] This embodiment uses a periodic lithium niobate waveguide to perform frequency conversion on the amplified fundamental frequency light. The periodic lithium niobate waveguide can withstand a power of 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 optical 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 accurately control the temperature of the periodic lithium niobate waveguide. The temperature control accuracy preferably reaches ±1mK, which can achieve temperature control in a small range to achieve fine control of the frequency doubling link and improve the power control accuracy of the frequency doubling link.

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

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

[0036] The contents not described in detail in the present invention belong to the prior art known to professionals in the field.

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

Claims

1. A frequency-doubled laser power stabilization system, characterized in that: It includes a seed light source (1), a first polarization-maintaining 2 optical fiber coupler (2), a first semiconductor pump source (3), a first polarization-maintaining combiner (4), a first polarization-maintaining doped optical fiber (5), a second semiconductor pump source (6), a second polarization-maintaining combiner (7), a second polarization-maintaining doped optical fiber (8), polarization-maintaining 1 Fiber coupler (9), periodic lithium niobate waveguide (10), temperature control system (11), second polarization maintaining device 1 2. Fiber optic coupler (12) and photodetector (13); The connection relationship between each part is: Seed light source (1) and first polarization-maintaining source 1 2 The first end of the optical fiber coupler (2) is fused, and the first polarization maintaining 1 The second end of the optical fiber coupler (2) is fused to the first end of the first polarization-maintaining beam combiner (4), the second end of the first polarization-maintaining beam combiner (4) is fused to one end of the first semiconductor pump source (3), the third end of the first polarization-maintaining beam combiner (4) is fused to one end of the first polarization-maintaining doped optical fiber (5), and the other end of the first polarization-maintaining doped optical fiber (5) is fused to the polarization-maintaining doped optical fiber (2).

1. The first end of the optical fiber coupler (9) is fused; First polarization 1 The third end of the optical fiber coupler (2) is fused to the first end of the second polarization-maintaining beam combiner (7), the second end of the second polarization-maintaining beam combiner (7) is fused to one end of the second semiconductor pump source (6), the third end of the second polarization-maintaining beam combiner (7) is fused to one end of the second polarization-maintaining doped optical fiber (8), and the other end of the second polarization-maintaining doped optical fiber (8) is fused to the polarization-maintaining doped optical fiber (8).

1. The second end of the optical fiber coupler (9) is fused; Polarization Maintaining 2 The third end of the optical fiber coupler (9) is fused to one end of the periodic lithium niobate waveguide (10), the periodic lithium niobate waveguide (10) is placed inside the temperature control system (11), and the other end of the periodic lithium niobate waveguide (10) is fused to the second polarization maintaining waveguide (11). 2 The first end of the optical fiber coupler (12) is fused, and the second end is polarization-maintaining 1 The second end of the optical fiber coupler (12) is connected to the photodetector (13), and the output signal of the photodetector (13) is used to control the second semiconductor pump source (6) and the temperature control system (11). Second polarization maintaining 1 The third end of the optical fiber coupler (12) serves as the output port of the frequency-doubled laser.

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

3. A frequency-doubling laser power stabilization system according to claim 1, characterized in that: The seed light source produces low-power fundamental frequency laser.

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

5. A frequency-doubling laser power stabilization system according to claim 1, characterized in that: The first semiconductor pump source (3) is a 940nm high-power multi-mode pump source, the first polarization-maintaining doped optical fiber (5) is an erbium-ytterbium co-doped optical fiber with high absorption of 940nm pump light, the length of which is 2m, and the main amplification optical path operates in a saturated pump state, mainly used for laser power enhancement.

6. A frequency-doubling laser power stabilization system according to claim 1, characterized in that: The second semiconductor pump source (6) is a 940nm low-power single-mode pump source, the second polarization-maintaining doped optical fiber (8) is an erbium-ytterbium co-doped optical fiber with high absorption of 940nm pump light, the length of which is 0.5m, and the secondary amplification optical path operates in a linear region and is used for power regulation during laser amplification.

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

8. A frequency-doubling laser power stabilization system 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 accurately control the temperature of the periodic lithium niobate waveguide (10), with a temperature control accuracy of ±1mK, to maintain a quasi-phase matching condition.

9. A frequency-doubling laser power stabilization system according to claim 1, characterized in that: The photoelectric detector (13) is a photodiode, which is used to monitor the frequency-doubled laser power in real time and output a feedback signal to control the working states of the second semiconductor pump source (6) and the temperature control system (11).

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

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