Pulse type narrow linewidth fiber laser device with pulse pre-shaping function

Abstract

The utility model discloses a pulse-type narrow-linewidth fiber laser device with a pulse pre-shaping function, and the device comprises a narrow-linewidth single-frequency continuous fiber laser which is used for generating single-frequency continuous laser output with the linewidth below 3kHz; the first acousto-optic modulator is used for modulating the single-frequency continuous laser into pre-shaped pulse laser; the single-cladding erbium-doped optical fiber amplifier is connected with the first acousto-optic modulator and is used for pre-amplifying the generated pulse laser; the second acousto-optic modulator is used for further improving the extinction ratio of the pulse laser; the double-cladding erbium-ytterbium co-doped optical fiber amplifier is connected with the second acousto-optic modulator and is used for further increasing the power of the pulse laser and outputting the pulse laser; and the dual-channel digital-to-analog conversion module is used for generating electric pulse signals used by the first acousto-optic modulator and the second acousto-optic modulator. According to the utility model, laser pulses can be pre-shaped into pulses with low front edges and high rear edges, so that the problem of different gains in the amplification process is solved, and the distortion degree of the laser pulses after power amplification is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of fiber lasers, and particularly relates to a pulsed narrow-linewidth fiber laser device with a pulse pre-shaping function. Background Technique

[0002] A fiber laser is a laser that uses rare-earth-doped optical fiber as a gain medium. Due to the difference in refractive index between the fiber cladding and the core, light will be confined to propagate within the core. With this characteristic, compared with solid-state lasers, it has higher beam quality, stronger anti-interference ability, and a more compact overall structure. Nowadays, fiber lasers have become the mainstream in the laser market. High-power narrow-linewidth pulsed fiber lasers are widely used in fields such as coherent lidar, fiber sensing, fiber communication, and laser processing due to their high beam quality, compact structure, narrow linewidth, and high power.

[0003] High-power narrow-linewidth pulsed fiber lasers usually use a continuous narrow-linewidth laser as a seed source and use an acousto-optic modulator to modulate it into pulsed laser. Its modulation principle is that when corresponding to a high-level pulse, the laser passes through the acousto-optic modulator with almost no loss, and when corresponding to a low level, the acousto-optic modulator introduces a very large loss so that the laser cannot pass through the device. In this way, pulsed laser is obtained. However, the laser power obtained in this way is small. Therefore, a fiber amplifier is needed for power amplification. Using ordinary square-wave pulses to modulate the laser, a light pulse with the same leading edge and trailing edge can be obtained after the initial modulation. When such a light pulse enters the fiber amplifier, since the leading edge obtains gain first, more gain will be obtained during the amplification process, resulting in less gain for the trailing edge part. Eventually, the amplified high-power pulse becomes a deformed pulse with a high leading edge and a low trailing edge.

[0004] In view of the above content, when modulating continuous laser, non-square-wave pulses are used for driving to obtain a pre-shaped light pulse, and the distortion degree of the laser pulse after power amplification is reduced. Content of the Utility Model

[0005] Aiming at the technical problems existing in the background technique, the purpose of the utility model is to provide a pulsed narrow-linewidth fiber laser device with a pulse pre-shaping function to solve the problem of laser pulse distortion of existing high-power narrow-linewidth pulsed fiber lasers proposed in the above background technique.

[0006] In order to achieve the above purpose, the technical scheme adopted by the utility model is as follows:

[0007] A pulsed narrow-linewidth fiber laser device with a pulse pre-shaping function, comprising:

[0008] A narrow-linewidth single-frequency continuous fiber laser, used to generate single-frequency continuous laser output with a linewidth below 3 kHz;

[0009] The first acousto-optic modulator is connected to the output end of the narrow linewidth single-frequency continuous fiber laser and is used to modulate the single-frequency continuous laser into pre-shaped pulsed laser;

[0010] The single-clad erbium-doped fiber amplifier is connected to the output end of the first acousto-optic modulator and is used to pre-amplify the generated pulsed laser;

[0011] The second acousto-optic modulator is connected to the output end of the single-clad erbium-doped fiber amplifier and is used to further improve the extinction ratio of the pulsed laser;

[0012] The double-clad erbium-ytterbium co-doped fiber amplifier is connected to the output end of the second acousto-optic modulator and is used to further increase the power of the pulsed laser and output it;

[0013] The dual-channel digital-to-analog conversion module is used to generate electrical pulse signals for the first acousto-optic modulator and the second acousto-optic modulator.

[0014] Further, the first acousto-optic modulator is a 40 MHz acousto-optic modulator with a working center wavelength of 1550 nm, supporting analog modulation mode and capable of modulating continuous laser into optical pulse signals with the same shape as the electrical pulse signal.

[0015] Further, the single-clad erbium-doped fiber amplifier includes an optical fiber isolator, a single-clad erbium-doped gain fiber, an optical fiber wavelength division multiplexer, an optical fiber band-pass filter, and a semiconductor single-mode pump laser. The optical fiber isolator, the single-clad erbium-doped gain fiber, the optical fiber wavelength division multiplexer, and the optical fiber band-pass filter are connected in sequence, and the semiconductor single-mode pump laser is connected to the reflection end of the optical fiber wavelength division multiplexer.

[0016] Wherein, the wavelength range of the semiconductor single-mode pump laser is 974 - 980 nm.

[0017] Further, the second acousto-optic modulator is an 80 MHz acousto-optic modulator with a working center wavelength of 1550 nm and supporting digital modulation or analog modulation mode.

[0018] Further, the double-clad erbium-ytterbium co-doped fiber amplifier includes an optical fiber isolator, a double-clad erbium-ytterbium co-doped gain fiber, an optical fiber pump combiner, and a multimode pump laser. The optical fiber isolator, the double-clad erbium-ytterbium co-doped gain fiber, and the optical fiber pump combiner are connected in sequence, and the multimode pump laser is connected to the optical fiber pump combiner.

[0019] Wherein, the input optical fiber of the double-clad erbium-ytterbium co-doped fiber amplifier and the connecting optical fiber between the double-clad erbium-ytterbium co-doped gain fiber and the optical fiber pump combiner are all PM-1550 optical fibers.

[0020] Further, the dual-channel digital-to-analog conversion module includes a dual-channel 125 Mbps digital-to-analog converter, a digital-to-analog converter peripheral circuit, an FPGA chip, and a chip peripheral circuit. The dual-channel 125 Mbps digital-to-analog converter and the digital-to-analog converter peripheral circuit are connected to the FPGA chip and the chip peripheral circuit. Two output terminals of the dual-channel 125 Mbps digital-to-analog converter and the digital-to-analog converter peripheral circuit are respectively connected to modulation input terminals of the first acousto-optic modulator and the second acousto-optic modulator.

[0021] The utility model has the following beneficial effects: There is provided a pulsed narrow-linewidth fiber laser device with a pulse pre-shaping function. When modulating continuous laser, a trapezoidal pulse with a low leading edge and a high trailing edge is used as the modulation signal. Because in traditional square-wave pulse modulation, the pulsed laser will be distorted into a deformed pulse with a high leading edge and a low trailing edge after amplification, while using a trapezoidal pulse can pre-shape the laser pulse into a pulse with a low leading edge and a high trailing edge to make up for the problem of different gains during the amplification process and reduce the distortion degree of the laser pulse after power amplification. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic structural diagram of the laser device of the utility model.

[0023] Figure 2 is a time-domain schematic diagram of an electrical pulse signal output by the dual-channel 125 Mbps digital-to-analog converter for use by a 40 MHz acousto-optic modulator.

[0024] Figure 3 is a time-domain schematic diagram of an electrical pulse signal output by the dual-channel 125 Mbps digital-to-analog converter for use by an 80 MHz acousto-optic modulator.

[0025] Figure 4 is a time-domain schematic diagram of a laser pulse output by a 40 MHz acousto-optic modulator.

[0026] Figure 5 is a time-domain schematic diagram of a laser pulse output by an 80 MHz acousto-optic modulator.

[0027] Figure 6 is a time-domain schematic diagram of a laser pulse output by a double-clad erbium-ytterbium co-doped fiber amplifier.

[0028] Description of main component symbols: 1. Narrow linewidth single-frequency continuous fiber laser; 2. First acousto-optic modulator; 3. Fiber isolator; 4. Single-clad erbium-doped gain fiber; 5. Fiber wavelength division multiplexer; 6. Semiconductor single-mode pump laser; 7. Fiber bandpass filter; 8. Second acousto-optic modulator; 9. Fiber isolator; 10. Double-clad erbium-ytterbium co-doped gain fiber; 11. Fiber pump combiner; 12. Multimode pump laser; 13. Dual-channel 125 Mbps digital-to-analog converter and its peripheral circuits; 14. FPGA chip and its peripheral circuits. Detailed implementation

[0029] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation manners.

[0030] As Figure 1 shown, the present invention discloses a pulsed narrow linewidth fiber laser device with a pulse pre-shaping function, including a narrow linewidth single-frequency continuous fiber laser 1, a first acousto-optic modulator 2, a single-clad erbium-doped fiber amplifier, a second acousto-optic modulator 8, a double-clad erbium-ytterbium co-doped fiber amplifier, and a dual-channel digital-to-analog conversion module.

[0031] The narrow linewidth single-frequency continuous fiber laser 1 is used to generate a single-frequency continuous laser output with a linewidth below 3 kHz.

[0032] The first acousto-optic modulator 2 is connected to the output end of the narrow linewidth single-frequency continuous fiber laser 1 and is used to modulate the single-frequency continuous laser into pre-shaped pulsed laser. The first acousto-optic modulator 1 is a 40 MHz acousto-optic modulator with a working center wavelength of 1550 nm, supporting analog modulation mode and capable of modulating continuous laser into an optical pulse signal with the same shape as the electrical pulse signal.

[0033] The single-clad erbium-doped fiber amplifier is connected to the output end of the first acousto-optic modulator 2 and is used to pre-amplify the generated pulsed laser. The single-clad erbium-doped fiber amplifier includes a fiber isolator 3, a single-clad erbium-doped gain fiber 4, a fiber wavelength division multiplexer 5, a semiconductor single-mode pump laser 6, and a fiber bandpass filter 7. The fiber isolator 3, the single-clad erbium-doped gain fiber 4, the fiber wavelength division multiplexer 5, and the fiber bandpass filter 7 are connected in sequence, and the semiconductor single-mode pump laser 6 is connected to the reflection end of the fiber wavelength division multiplexer 5. The wavelength range of the semiconductor single-mode pump laser 6 is 974 - 980 nm.

[0034] The second acousto-optic modulator 8, which is connected to the output end of the single-clad erbium-doped fiber amplifier, is used to further improve the extinction ratio of the pulsed laser. The second acousto-optic modulator 8 is an 80 MHz acousto-optic modulator with a working center wavelength of 1550 nm and supporting digital modulation or analog modulation mode.

[0035] The double-clad erbium-ytterbium co-doped fiber amplifier is connected to the output end of the second acousto-optic modulator 8 for further increasing the power of the pulsed laser and outputting it. The double-clad erbium-ytterbium co-doped fiber amplifier includes an optical fiber isolator 9, a double-clad erbium-ytterbium co-doped gain fiber 10, an optical fiber pump combiner 11, and a multimode pump laser 12. The optical fiber isolator 9, the double-clad erbium-ytterbium co-doped gain fiber 10, and the optical fiber pump combiner 11 are connected in sequence, and the multimode pump laser 12 is connected to the optical fiber pump combiner 11. The input optical fiber of the double-clad erbium-ytterbium co-doped fiber amplifier and the connecting optical fiber between the double-clad erbium-ytterbium co-doped gain fiber 10 and the optical fiber pump combiner 11 are all PM-1550 optical fibers. The optical fiber pump combiner 11 is a (1 + 1)×1 optical fiber pump combiner, and the maximum output power of the multimode pump laser 12 is 10W.

[0036] The dual-channel digital-to-analog conversion module is used to generate electrical pulse signals for the first acousto-optic modulator 2 and the second acousto-optic modulator 8. The dual-channel digital-to-analog conversion module includes a dual-channel 125 Mbps digital-to-analog converter and its peripheral circuit 13, an FPGA chip and its peripheral circuit 14. The dual-channel 125 Mbps digital-to-analog converter and its peripheral circuit 13 are connected to the FPGA chip and its peripheral circuit 14, and the two output ends of the dual-channel 125 Mbps digital-to-analog converter and its peripheral circuit 13 are respectively connected to the modulation input ends of the first acousto-optic modulator 2 and the second acousto-optic modulator 8.

[0037] As Figure 2 shown is the time-domain schematic diagram of the electrical pulse signal output by the dual-channel 125 Mbps digital-to-analog converter for the 40 MHz acousto-optic modulator. As Figure 3 shown is the time-domain schematic diagram of the electrical pulse signal output by the dual-channel 125 Mbps digital-to-analog converter for the 80 MHz acousto-optic modulator. As Figure 4 shown is the time-domain schematic diagram of the laser pulse output by the 40 MHz acousto-optic modulator. As Figure 5 shown is the time-domain schematic diagram of the laser pulse output by the 80 MHz acousto-optic modulator. As Figure 6 shown is the time-domain schematic diagram of the laser pulse output by the double-clad erbium-ytterbium co-doped fiber amplifier.

[0038] When the present invention modulates continuous laser, a trapezoidal pulse with a low leading edge and a high trailing edge is used as the modulation signal. Because in the traditional square-wave pulse modulation, the pulsed laser will be distorted into a deformed pulse with a high leading edge and a low trailing edge after amplification, while using a trapezoidal pulse can pre-shape the laser pulse into a pulse with a low leading edge and a high trailing edge to make up for the problem of different gains in the amplification process.

[0039] Although the present utility model has been specifically shown and described in connection with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the present utility model without departing from the spirit and scope of the present utility model as defined by the appended claims.

Claims

1. A pulsed narrow linewidth fiber laser device with pulse pre-shaping function, characterized in that: include: Narrow linewidth single-frequency continuous fiber laser, used to generate single-frequency continuous laser output with a linewidth below 3kHz; A first acousto-optic modulator is connected to the output end of the narrow-linewidth single-frequency continuous fiber laser and is used to modulate the single-frequency continuous laser into a pre-shaped pulse laser; A single-clad erbium-doped fiber amplifier is connected to the output end of the first acousto-optic modulator and is used to pre-amplify the generated pulse laser; A second acousto-optic modulator is connected to the output end of the single-clad erbium-doped fiber amplifier and is used to further improve the extinction ratio of the pulsed laser; A double-clad erbium-ytterbium co-doped fiber amplifier connected to the output end of the second acousto-optic modulator, used to further increase the power of the pulsed laser and output it; The dual-channel digital-to-analog conversion module is used to generate an electrical pulse signal for use by the first acousto-optic modulator and the second acousto-optic modulator.

2. A pulsed narrow linewidth fiber laser device with pulse pre-shaping function as claimed in claim 1, characterized in that: The first acousto-optic modulator is a 40MHz acousto-optic modulator with a working center wavelength of 1550nm, supporting analog modulation mode and capable of modulating continuous laser light into an optical pulse signal with the same shape as the electrical pulse signal.

3. A pulsed narrow linewidth fiber laser device with pulse pre-shaping function as claimed in claim 1, characterized in that: The single-clad erbium-doped fiber amplifier comprises an optical fiber isolator, a single-clad erbium-doped gain fiber, an optical fiber wavelength division multiplexer, an optical fiber bandpass filter and a semiconductor single-mode pump laser. The optical fiber isolator, the single-clad erbium-doped gain fiber, the optical fiber wavelength division multiplexer and the optical fiber bandpass filter are connected in sequence, and the semiconductor single-mode pump laser is connected to the reflection end of the optical fiber wavelength division multiplexer.

4. A pulsed narrow linewidth fiber laser device with pulse pre-shaping function as claimed in claim 3, characterized in that: The wavelength range of the semiconductor single-mode pump laser is 974-980nm.

5. A pulsed narrow linewidth fiber laser device with pulse pre-shaping function as claimed in claim 1, characterized in that: The second acousto-optic modulator is an 80 MHz acousto-optic modulator with a working center wavelength of 1550 nm and supporting digital modulation or analog modulation.

6. A pulsed narrow linewidth fiber laser device with pulse pre-shaping function as claimed in claim 1, characterized in that: The double-clad erbium-ytterbium co-doped fiber amplifier comprises a fiber isolator, a double-clad erbium-ytterbium co-doped gain fiber, a fiber pump combiner and a multimode pump laser. The fiber isolator, the double-clad erbium-ytterbium co-doped gain fiber and the fiber pump combiner are connected in sequence, and the multimode pump laser is connected to the fiber pump combiner.

7. A pulsed narrow linewidth fiber laser device with pulse pre-shaping function as claimed in claim 6, characterized in that: The input end optical fiber of the double-clad erbium-ytterbium co-doped optical fiber amplifier, the connecting optical fiber between the double-clad erbium-ytterbium co-doped gain optical fiber and the optical fiber pump combiner are all PM-1550 optical fibers.

8. A pulsed narrow linewidth fiber laser device with pulse pre-shaping function as claimed in claim 1, characterized in that: The dual-channel digital-to-analog conversion module includes a dual-channel 125Mbps digital-to-analog converter, a digital-to-analog converter peripheral circuit, an FPGA chip and a chip peripheral circuit. The dual-channel 125Mbps digital-to-analog converter and the digital-to-analog converter peripheral circuit are connected to the FPGA chip and the chip peripheral circuit. The two output ends of the dual-channel 125Mbps digital-to-analog converter and the digital-to-analog converter peripheral circuit are respectively connected to the modulation input ends of the first acousto-optic modulator and the second acousto-optic modulator.

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