A frequency-shifted continuous fiber laser for short-range coherent Doppler lidar

Abstract

The present invention discloses a frequency-shifted continuous fiber laser for a close-range coherent Doppler laser radar, comprising a laser body, wherein the laser body comprises a narrow-linewidth laser seed source, a beam splitter, a fiber amplifier, an acousto-optic modulator, an acousto-optic radio frequency driver, a circulator and an output component, wherein the output end of the narrow-linewidth laser seed source is connected to the input end of the beam splitter, the beam splitter is used to receive a narrow-linewidth continuous laser signal generated by the narrow-linewidth laser seed source, and the beam splitter has two output ends, one of which is used as a local oscillator light signal output. The frequency-shifted continuous fiber laser for a close-range coherent Doppler laser radar provided by the present invention can realize continuous adjustable output power of a narrow-linewidth laser signal from 0 to 1W by adjusting the pump current of the fiber amplifier and the modulation voltage of the acousto-optic modulator, which is beneficial to reducing the blind area of ​​the coherent Doppler laser radar during close-range testing.

Description

Technical Field

[0001] The invention relates to the technical field of lasers, and in particular to a frequency-shifted continuous fiber laser for a close-range coherent Doppler laser radar. Background Art

[0002] High-power narrow-linewidth fiber lasers are widely used in coherent Doppler radar, gas detection and other fields. Coherent Doppler lidar uses the scattering effect of aerosol particles on narrow-linewidth laser signals to obtain the Doppler frequency shift of the scattered light and the local oscillator light signal, thereby inverting and calculating the wind speed information on the laser transmission path.

[0003] Although coherent Doppler lidar has been applied to fields such as meteorological detection and aviation navigation, the existing laser light sources still have some defects. Currently, frequency-shifted pulse lasers are widely used as signal sources in coherent Doppler lidar.

[0004] In order to increase the radar detection distance, lasers with higher single pulse energy are usually selected. However, due to the high peak power of near-field light pulses, the power of the short-range return signal received by the detector is saturated, and the effective information is submerged, which makes the coherent Doppler laser radar have a blind area that cannot be detected during close-range testing. Therefore, it is urgent to design a frequency-shifted continuous fiber laser for close-range coherent Doppler laser radar to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a frequency-shifted continuous fiber laser for a close-range coherent Doppler laser radar to solve the above-mentioned deficiencies in the prior art.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A frequency-shifted continuous fiber laser for a close-range coherent Doppler laser radar comprises a laser body, wherein the laser body comprises a narrow-linewidth laser seed source, a spectrometer, a fiber amplifier, an acousto-optic modulator, an acousto-optic radio frequency driver, a circulator and an output component, wherein the output end of the narrow-linewidth laser seed source is connected to the input end of the spectrometer, the spectrometer is used to receive a narrow-linewidth continuous laser signal generated by the narrow-linewidth laser seed source, the spectrometer has two output ends, one of which is used as a local oscillator optical signal output, and the other output end is connected to the fiber amplifier, the output end of the fiber amplifier is connected to the optical input end of the acousto-optic modulator, and the radio frequency input end of the acousto-optic modulator is connected to the acousto-optic radio frequency driver, the output end of the acousto-optic modulator is connected to the circulator, and the circulator is connected to the output component.

[0008] The circulator is a three-port circulator, including a first port, a second port and a third port. The output end of the acousto-optic modulator is connected to the first port of the circulator, and the output component is connected to the second port of the circulator.

[0009] The narrow linewidth laser seed source is a semiconductor laser or a fiber laser.

[0010] The narrow line width laser seed source has an operating wavelength of 1.0 μm, 1.5 μm or 2.0 μm.

[0011] The line width of the narrow line width laser seed source is less than 300 kHz.

[0012] The optical splitter is a 1×2 optical splitter.

[0013] The optical fiber amplifier is one of an ytterbium-doped optical fiber amplifier, an erbium-doped optical fiber amplifier, a thulium-doped optical fiber amplifier, an erbium-ytterbium co-doped optical fiber amplifier or a thulium-holmium co-doped optical fiber amplifier.

[0014] The optical fiber amplifier is one of a forward pumped optical fiber amplifier, a reverse pumped optical fiber amplifier or a bidirectional pumped optical fiber amplifier.

[0015] The modulation mode of the acousto-optic radio frequency drive is analog modulation.

[0016] The output component is an optical fiber jumper head or a magneto-optical switch or a MEMS optical switch.

[0017] In the above technical solution, the present invention provides a frequency-shifted continuous fiber laser for a close-range coherent Doppler laser radar, which has the following beneficial effects:

[0018] (1) The frequency-shifted continuous fiber laser for close-range coherent Doppler laser radar provided by the present invention can achieve continuous adjustment of the output power of the narrow-linewidth laser signal from 0 to 1 W by adjusting the pump current of the fiber amplifier and the modulation voltage of the acousto-optic modulator, which is beneficial to reducing the blind area of ​​the coherent Doppler laser radar during close-range testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0020] Figure 1 The present invention provides a schematic diagram of the overall structure of a frequency-shifted continuous fiber laser embodiment for use in a close-range coherent Doppler laser radar.

[0021] Figure 2A schematic diagram of the structure of a splitter port provided in an embodiment of a frequency-shifted continuous fiber laser for a close-range coherent Doppler laser radar of the present invention.

[0022] Figure 3 A schematic diagram of the circulator port structure provided in an embodiment of a frequency-shifted continuous fiber laser for a close-range coherent Doppler laser radar of the present invention.

[0023] 1. Narrow linewidth laser seed source; 2. Optical splitter; 2.1. First output port; 2.2. Second output port; 3. Fiber amplifier; 4. Acousto-optic modulator; 5. Acousto-optic RF driver; 6. Circulator; 6.1. First port; 6.2. Second port; 6.3. Third port; 7. Output component. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0025] like Figure 1-3 As shown, a frequency-shifted continuous fiber laser for a close-range coherent Doppler laser radar provided by an embodiment of the present invention comprises a laser body, wherein the laser body comprises a narrow-linewidth laser seed source 1, a beam splitter 2, a fiber amplifier 3, an acousto-optic modulator 4, an acousto-optic radio frequency driver 5, a circulator 6 and an output component 7, wherein the output end of the narrow-linewidth laser seed source 1 is connected to the input end of the beam splitter 2, the beam splitter 2 is used to receive a narrow-linewidth continuous laser signal generated by the narrow-linewidth laser seed source 1, and the beam splitter 2 has two output ends, one of which is used as a local oscillator light signal output end. The other output end is connected to the optical fiber amplifier 3, the output end of the optical fiber amplifier 3 is connected to the optical input end of the acousto-optic modulator 4, and the RF input end of the acousto-optic modulator 4 is connected to the acousto-optic RF driver 5, the output end of the acousto-optic modulator 4 is connected to the circulator 6, and the circulator 6 is connected to the output component 7, the circulator 6 is a three-port circulator, including a first port 6.1, a second port 6.2 and a third port 6.3, the output end of the acousto-optic modulator 4 is connected to the first port 6.1 of the circulator 6, and the output component 7 is connected to the second port 6.2 of the circulator 6.

[0026] Specifically, in the present embodiment, the optical splitter 2 has two output ends, one of which is used as the output of the local oscillator optical signal, and the other is connected to the optical fiber amplifier 3, which is used to amplify the laser signal and roughly adjust the power. The output end of the optical fiber amplifier 3 is connected to the optical input end of the acousto-optic modulator 4, which is used to frequency-shift and attenuate the amplified laser signal, and the RF input end of the acousto-optic modulator 4 is connected to the acousto-optic RF driver 5, which adjusts the modulation voltage, thereby realizing the fine adjustment of the optical power of the laser signal passing through the acousto-optic modulator 4. The output end of the acousto-optic modulator 4 is connected to the first port 6.1 of the circulator 6, and the second port 6.2 of the circulator 6 is connected to the output component 7, which cooperates with the telephoto lens to perform common aperture transmission and reception of the laser signal after frequency shifting in the emission direction.

[0027] The present invention provides a frequency-shifted continuous fiber laser for a close-range coherent Doppler laser radar, wherein a narrow-linewidth laser seed source 1 is a semiconductor laser or a fiber laser, the operating wavelength of the narrow-linewidth laser seed source 1 is 1.0 μm, 1.5 μm or 2.0 μm, the linewidth of the narrow-linewidth laser seed source 1 is less than 300 kHz, the optical splitter 2 is a 1×2 optical splitter, the optical fiber amplifier 3 is one of an ytterbium-doped optical fiber amplifier, an erbium-doped optical fiber amplifier, a thulium-doped optical fiber amplifier, an erbium-ytterbium co-doped optical fiber amplifier or a thulium-holmium co-doped optical fiber amplifier, the optical fiber amplifier 3 is one of a forward pumped optical fiber amplifier, a reverse pumped optical fiber amplifier or a bidirectional pumped optical fiber amplifier, the modulation mode of the acousto-optic radio frequency driver 5 is analog modulation, the output component 7 is an optical fiber jumper head or a magneto-optical switch or a MEMS optical switch, and the two output ends of the optical splitter 2 are respectively a first output port 2.1 and a second output port 2.2.

[0028] In another embodiment provided by the present invention, the narrow line width laser seed source 1 has a working center wavelength of 1550.12 nm, a line width of 3 kHz, an output power of 20 mW, and an output of PM1550 optical fiber. The narrow line width laser seed source 1 is connected to the output port of the optical splitter 2 by optical fiber fusion splicing;

[0029] The optical splitter 2 is a 1×2 PM1550 coupler with a splitting ratio of 80:20. The first output port 2.1 of the optical splitter 2 is connected to the optical fiber amplifier 3 through optical fiber fusion splicing, and the second output port 2.2 of the optical splitter 2 outputs a local oscillator optical signal;

[0030] The fiber amplifier 3 is a reverse-pumped erbium-ytterbium co-doped fiber amplifier, which uses a 940nm semiconductor laser as a pump source and PM1550 optical fiber for transmission; the internal components of the fiber amplifier 3 are connected by optical fiber fusion splicing, and the fiber amplifier 3 is connected to the acousto-optic modulator 4 by optical fiber fusion splicing;

[0031] The working wavelength of the acousto-optic modulator 4 is 1550nm and the frequency shift is 80MHz. The acousto-optic modulator 4 is connected to the first port 6.1 of the circulator 6 by optical fiber fusion splicing;

[0032] The operating frequency of the acousto-optic RF driver 5 is 80 MHz, and the modulation voltage range is 0 to 1 V. The acousto-optic RF driver 5 is connected to the acousto-optic modulator 4 via an SMA coaxial RF cable;

[0033] The output component 7 is a 1×4 MEMS optical switch made of PM1550 optical fiber, which cooperates with 4 sets of telephoto lenses to complete the common aperture transmission and reception of the frequency-shifted laser signal in the 4 emission directions. The output component 7 is connected to the second port 6.2 of the circulator by optical fiber fusion splicing;

[0034] The circulator 6 is a three-port circulator, and the second port 6.2 is also used to receive the scattered light return signal collected by the output component 7 and output it through the third port 6.3.

[0035] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A frequency-shifted continuous fiber laser for close-range coherent Doppler laser radar, characterized in that: The invention comprises a laser body, wherein the laser body comprises a narrow line width laser seed source (1), a beam splitter (2), an optical fiber amplifier (3), an acousto-optic modulator (4), an acousto-optic radio frequency driver (5), a circulator (6) and an output component (7). The output end of the narrow line width laser seed source (1) is connected to the input end of the beam splitter (2). The beam splitter (2) is used to receive a narrow line width continuous laser signal generated by the narrow line width laser seed source (1). The beam splitter (2) has two output ends, one of which is used as a local oscillator optical signal output, and the other output end is connected to the optical fiber amplifier (3). The output end of the optical fiber amplifier (3) is connected to the optical input end of the acousto-optic modulator (4), and the radio frequency input end of the acousto-optic modulator (4) is connected to the acousto-optic radio frequency driver (5). The output end of the acousto-optic modulator (4) is connected to the circulator (6), and the circulator (6) is connected to the output component (7).

2. The frequency-shifted continuous fiber laser for close-range coherent Doppler laser radar according to claim 1, characterized in that: The circulator (6) is a three-port circulator, comprising a first port (6.1), a second port (6.2) and a third port (6.3); the output end of the acousto-optic modulator (4) is connected to the first port (6.1) of the circulator (6), and the output component (7) is connected to the second port (6.2) of the circulator (6).

3. The frequency-shifted continuous fiber laser for close-range coherent Doppler laser radar according to claim 1, characterized in that: The narrow linewidth laser seed source (1) is a semiconductor laser or a fiber laser.

4. The frequency-shifted continuous fiber laser for close-range coherent Doppler laser radar according to claim 3, characterized in that: The operating wavelength of the narrow linewidth laser seed source (1) is 1.0 μm, 1.5 μm or 2.0 μm.

5. The frequency-shifted continuous fiber laser for close-range coherent Doppler laser radar according to claim 4, characterized in that: The line width of the narrow line width laser seed source (1) is less than 300 kHz.

6. The frequency-shifted continuous fiber laser for close-range coherent Doppler laser radar according to claim 1, characterized in that: The optical splitter (2) is a 1×2 optical splitter.

7. The frequency-shifted continuous fiber laser for close-range coherent Doppler laser radar according to claim 1, characterized in that: The optical fiber amplifier (3) is one of an ytterbium-doped optical fiber amplifier, an erbium-doped optical fiber amplifier, a thulium-doped optical fiber amplifier, an erbium-ytterbium co-doped optical fiber amplifier, or a thulium-holmium co-doped optical fiber amplifier.

8. The frequency-shifted continuous fiber laser for close-range coherent Doppler laser radar according to claim 7, characterized in that: The optical fiber amplifier (3) is one of a forward pumped optical fiber amplifier, a reverse pumped optical fiber amplifier or a bidirectional pumped optical fiber amplifier.

9. The frequency-shifted continuous fiber laser for close-range coherent Doppler laser radar according to claim 1, characterized in that: The modulation mode of the acousto-optic radio frequency drive (5) is analog modulation.

10. The frequency-shifted continuous fiber laser for close-range coherent Doppler laser radar according to claim 1, characterized in that: The output component (7) is an optical fiber jumper head or a magneto-optical switch or a MEMS optical switch.

Images