Homodyne detection Doppler wind measurement laser radar device based on silicon optical chip

Abstract

A homodyne detection Doppler wind measurement laser radar device based on a silicon optical chip comprises a light source module, a photoelectron chip module, a semiconductor optical amplifier, an erbium-doped optical fiber amplifier, an optical circulator, an optical transceiver antenna, a transimpedance amplifier processing module, an A / D acquisition card module, a digital signal processing module and a display and storage module. Discrete devices such as a beam splitter, a frequency mixer and a detector in an optical fiber link are integrated on one chip, high-density integration with other components is carried out through the photoelectric hybrid packaging technology, and chipping and miniaturization of the all-optical-fiber wind finding radar are achieved. The semiconductor optical amplifier (SOA) is used for chopping, a homodyne detection method is used for eliminating the requirement for frequency shift, and compared with a traditional Doppler wind measurement laser radar, the Doppler wind measurement laser radar has the advantages of being small in power consumption, small in size, light in weight, high in integration level, convenient to produce in a large scale, low in cost of a single device and the like.

Description

Technical Field

[0001] The present invention relates to the field of laser radar, and in particular to a homodyne detection Doppler wind measurement laser radar device based on a silicon photonic chip and a measurement method thereof. Background Art

[0002] Doppler wind laser radar is an effective means of measuring atmospheric wind field information with high temporal and spatial resolution and high precision. It has been widely used in meteorological forecasting, wind power generation, aerospace and other fields at home and abroad. Pulse Doppler laser radar emits laser pulses into the atmosphere and measures the Doppler frequency shift of the backscattered light in the direction of the laser due to the movement of aerosol particles to determine the apparent wind speed. Typical all-fiber coherent Doppler wind laser radar can only exist in the system in the form of discrete devices because the optical fiber components and their driver modules used in the optical fiber link need to be packaged based on different processes. Limited by the size of the discrete components themselves and the bending radius of the optical fiber, the integration of the all-fiber Doppler laser radar is difficult to further improve. The use of optoelectronic chip technology can integrate discrete devices such as beam splitters, mixers, and detectors in the optical fiber link on a chip. Through optoelectronic hybrid packaging technology, high-density integration with other components can be achieved, which can realize the chipization and miniaturization of the all-fiber structure wind radar, significantly improving the integration of the system. Traditional pulse Doppler lidar usually adopts the heterodyne detection principle, and uses an acousto-optic modulator (AOM) to pulse modulate the continuous seed light and achieve frequency shift, thereby achieving distance resolution and direction judgment of Doppler frequency shift (wind speed). Therefore, to realize Doppler lidar based on silicon photonic chips, it is necessary to solve high extinction ratio pulse modulation and Doppler frequency shift sign judgment. However, the existing on-chip integrated AOM mostly adopts the MZI (Mach-Zehnder interferometer) structure, which uses surface acoustic waves to change the phase of the light beam in the two arms of the interferometer to achieve modulation. The extinction ratio can only reach 40dB at most (discrete AOM can stably reach 60dB), and there are limitations such as low efficiency, high energy consumption, and unstable performance, which cannot meet the laser radar pulse extinction ratio requirements. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that it is difficult to further improve the integration of the traditional all-fiber Doppler wind measurement lidar. A homodyne detection Doppler wind measurement lidar device based on a silicon photonic chip is provided. The device is based on optoelectronic chip technology and uses a semiconductor optical amplifier (SOA) for chopping. At the same time, homodyne detection technology is used to eliminate the need for frequency shifting. The semiconductor optical amplifier (SOA) is a chip structure device with the characteristics of amplifying the incident light when a driving current is applied and absorbing the incident light when no driving current is applied. It can form pulse modulation with a higher extinction ratio while reducing power consumption and insertion loss. When used as a chopper, it can solve the problems existing in the on-chip AOM.

[0004] The present invention not only eliminates the limitations of on-chip acousto-optic modulators, but also can realize the chipization and miniaturization of all-fiber structure wind measurement radar, and has the advantages of low power consumption, small size, light weight, high integration, convenience for mass production, and low cost of a single device.

[0005] The technical solution of the present invention is as follows:

[0006] A homodyne detection Doppler wind measurement laser radar device based on silicon photonic chip, comprising: a light source module, an optoelectronic chip module, a semiconductor optical amplifier, an erbium-doped fiber amplifier, an optical circulator, an optical transceiver antenna, a transimpedance amplifier processing module, an A / D acquisition card module, a digital signal processing module, and a display and storage module;

[0007] The light source module emits a continuous laser, which enters the optoelectronic chip module and is divided into two paths, one of which is used as the local oscillator light, and the other is chopped by the semiconductor optical amplifier to become a pulse light, which is amplified by the erbium-doped fiber amplifier, and then emitted into the atmosphere by the optical transceiver antenna after passing through the optical circulator, interacts with aerosol particles in the atmosphere to produce a Doppler frequency shift, and the backscattered signal light is received by the optical transceiver antenna, re-enters the optoelectronic chip module through the optical circulator, beats with the local oscillator light in the optoelectronic chip module and performs photoelectric conversion, and the output of the optoelectronic chip module contains the Doppler frequency shift. The current signal is converted into a voltage signal by the transimpedance amplifier processing module, converted into a digital signal by the A / D acquisition card module, and the digital signal processing module performs fast Fourier transform (FFT) and IQ demodulation to obtain the apparent wind speed, which is stored by the display and storage module. The light source module, optoelectronic chip module, semiconductor optical amplifier, and transimpedance amplifier processing module are mounted on a high-frequency silicon substrate and mounted on a copper plate of a thermoelectric cooler and packaged together in a high-frequency tube shell. The thermoelectric cooler is used to provide a constant operating temperature for the light source module, optoelectronic chip module, semiconductor optical amplifier, and transimpedance amplifier processing module. The light source module can detect the light intensity and temperature information of the laser in real time when it is working, and perform feedback control based on the information obtained to maintain the stable operation of the laser.

[0008] The light source module further includes a laser chip, a first lens, an isolator, a polarizer, a second lens, a backlight detector and a temperature sensor;

[0009] The laser beam emitted by the laser chip is collimated by the first lens, reaches the polarizer through the isolator, becomes linearly polarized light, and then is focused by the second lens and incident on the optoelectronic chip module. The backlight detector is used to receive the light beam emitted back from the laser chip to monitor the light intensity of the output light of the laser chip. The temperature sensor is placed next to the laser chip to monitor the operating temperature of the laser chip.

[0010] The optoelectronic chip module further comprises a first end coupler, a second end coupler, a third end coupler, a beam splitter, a 90° optical mixer, a first photodetector, a second photodetector, a third photodetector and a fourth photodetector;

[0011] After the laser is incident from the first end face coupler, it is divided into two paths by the beam splitter. One path is used as local oscillation light to enter the local oscillator end of the 90° optical mixer, and the other path is used as a signal light carrier and is output by the second end face coupler. The signal light with Doppler frequency shift information is input to the signal end of the 90° optical mixer by the third end face coupler. The 90° optical mixer outputs 4 optical signals, which respectively enter the first, second, third and fourth photoelectric detectors for photoelectric conversion. The current signals output by the first photoelectric detector and the second photoelectric detector are beat-frequencyed. The two beat-frequency signals differ in phase by 90° and are used for IQ demodulation to determine the positive or negative of the Doppler frequency shift, thereby determining the direction of the apparent wind speed.

[0012] The present invention obtains the movement speed of aerosol particles in the visual direction by extracting the Doppler frequency shift generated by the interaction between the emitted laser and the aerosol particles. The wavelength of the emitted laser of the light source module is λ, the frequency is f0, the speed of light is c, the Doppler frequency shift caused by the movement of the aerosol particles is Δf, and the visual wind speed v LOS It can be expressed as:

[0013]

[0014] The amplitude is E l , the initial phase is The local oscillator light can be expressed as:

[0015]

[0016] The emitted laser interacts with aerosol particles in the atmosphere, produces a Doppler frequency shift, and is then received by the optical transceiver antenna with an amplitude of E. s , the initial phase is The received signal light can be expressed as:

[0017]

[0018] The 90° optical mixer is used to mix the local oscillator light with the signal light to generate 4 output optical signals, wherein the local oscillator light has a 90° phase difference (0°, 90°, 180°, 270°), the 0° and 180° signals enter the first photodetector and the second photodetector for photoelectric conversion and beat frequency to form an I channel, the 90° and 270° signals enter the third photodetector and the fourth photodetector for photoelectric conversion and beat frequency to form a Q channel, and the signals of the I channel and the Q channel can be expressed as follows:

[0019]

[0020]

[0021] Performing fast Fourier transform (FFT) on the I and Q channels respectively, we can get:

[0022]

[0023]

[0024] By orthogonalizing formula (6) and formula (7) and taking the imaginary part, we can get:

[0025]

[0026] Formula (8) can be used to determine the magnitude and sign of the Doppler frequency shift, and thus the magnitude and direction of the apparent wind speed can be determined using formula (1).

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1) Based on optoelectronic chip technology, the present invention integrates a large number of components of the Doppler wind laser radar on a small silicon photonic chip, which significantly reduces the volume and power consumption of the system, and is conducive to the compactness and miniaturization of the Doppler wind laser radar.

[0029] 2) The present invention utilizes a semiconductor optical amplifier to replace the acousto-optic modulator in the conventional technology to realize chopping, which can reduce insertion loss and improve output optical power while obtaining pulse light with a higher extinction ratio. In addition, the semiconductor optical amplifier of the present invention is a chip-structured device and is more suitable for on-chip integration.

[0030] 3) The present invention adopts a homodyne detection method to obtain the magnitude and direction of the wind speed through IQ demodulation, eliminating the limitation of traditional heterodyne detection technology that requires the introduction of the frequency difference between the local oscillator light and the signal light to determine the sign of the Doppler frequency shift. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1It is a structural block diagram of a homodyne detection Doppler wind measurement laser radar device based on a silicon photonic chip of the present invention;

[0032] Figure 2 is a structural block diagram of a light source module of the present invention;

[0033] Figure 3 It is a structural block diagram of the optoelectronic chip module of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with embodiments and drawings, but the protection scope of the present invention shall not be limited thereto.

[0035] See also Figure 1 , Figure 1 The present invention is a structural block diagram of a homodyne detection Doppler wind measurement laser radar device based on a silicon photonic chip. As can be seen from the figure, the homodyne detection Doppler wind measurement laser radar device based on a silicon photonic chip of the present invention includes: a light source module 1, an optoelectronic chip module 2, a semiconductor optical amplifier 3, an erbium-doped fiber amplifier 4, an optical circulator 5, an optical transceiver antenna 6, a transimpedance amplifier processing module 7, an A / D acquisition card module 8, a digital signal processing module 9, and a display and storage module 10;

[0036] The output end of the light source module 1 is connected to the first input end of the optoelectronic chip module 2, the optical signal output end of the optoelectronic chip module 2 is connected to the input end of the semiconductor optical amplifier 3, the output end of the semiconductor optical amplifier 3 is connected to the input end of the erbium-doped fiber amplifier 4, the output end of the erbium-doped fiber amplifier 4 is connected to the first port of the optical circulator 5, the optical transceiver antenna 6 is connected to the second port of the optical circulator 5, the laser emitted from the optical signal output end of the optoelectronic chip module 2 is chopped by the semiconductor optical amplifier 3 to become a pulse light with a high extinction ratio, and passes through the erbium-doped fiber amplifier 4 is amplified, and then transmitted into the atmosphere after passing through the optical circulator 5 and the optical transceiver antenna 6, and interacts with the aerosol particles in the atmosphere to generate a Doppler frequency shift; the third port of the optical circulator 5 is connected to the second input end of the optoelectronic chip module 2, and is used to input the signal light received by the optical transceiver antenna 6 into the optoelectronic chip module 2 for processing, and the electrical signal output port of the optoelectronic chip module 2 outputs two electrical signals respectively, which enter the digital signal processing module 9 through the transimpedance amplifier processing module 7 and the A / D acquisition card module 8 in turn, and the digital signal processing module 9 is connected to the display and storage module 10;

[0037] The light source module 1, optoelectronic chip module 2, semiconductor optical amplifier 3 and transimpedance amplifier processing module 7 are mounted on a high-frequency silicon substrate and mounted on a copper plate of a thermoelectric cooler and packaged together in a high-frequency tube shell. The thermoelectric cooler is used to provide a constant operating temperature for the light source module 1, optoelectronic chip module 2, semiconductor optical amplifier 3 and transimpedance amplifier processing module 7.

[0038] See also Figure 2 , Figure 2 1 is a structural block diagram of a light source module 1 of the present invention, wherein the light source module 1 comprises a laser chip 1-1, a first lens 1-2, an isolator 1-3, a polarizer 1-4, a second lens 1-5, a backlight detector 1-6 and a temperature sensor 1-7;

[0039] The laser chip 1-1 emits a laser beam, which is collimated by the first lens 1-2 and then incident on the isolator 1-3. After passing through the isolator 1-3, it reaches the polarizer 1-4. After passing through the polarizer 1-4, the beam becomes linearly polarized light, which is focused by the second lens 1-5 and then input into the optoelectronic chip module 2. The beam emitted backward by the laser chip 1-1 is received and detected by the backlight detector 1-6. The temperature sensor 1-7 is placed next to the laser chip 1-1 to detect the working temperature of the laser chip.

[0040] See also Figure 3 , Figure 3 : is a structural block diagram of the optoelectronic chip module 2 of the present invention. As can be seen from the figure, the optoelectronic chip module 2 further includes a first end coupler 2-1, a second end coupler 2-2, a third end coupler 2-3, a beam splitter 2-4, a 90° optical mixer 2-5, a first photodetector 2-6, a second photodetector 2-7, a third photodetector 2-8 and a fourth photodetector 2-9;

[0041] The laser emitted by the light source module 1 enters the beam splitter 2-4 after being incident on the first end coupler 2-1 of the optoelectronic chip module 2, and is divided into two outputs in the beam splitter 2-4. The beam splitter 2-4 preferably adopts a 95:5 beam splitter, which is used to input 5% of the laser energy into the first input end of the 90° optical mixer 2-5 as local oscillation light, and input 95% of the laser energy into the semiconductor optical amplifier 3 through the second end coupler 2-2. The backscattered signal light is incident on the 90° optical mixer 2-5 from the third end coupler 2-3. The 90° optical mixer 2-5 is used to mix the local oscillator light with the signal light to generate 4 output optical signals, wherein the local oscillator light has a 90° phase difference (0°, 90°, 180°, 270°). The 0° and 180° signals enter the first photodetector 2-6 and the second photodetector 2-7 for photoelectric conversion and beat frequency to form an I channel. The 90° and 270° signals enter the third photodetector 2-8 and the fourth photodetector 2-9 for photoelectric conversion and beat frequency to form a Q channel.

[0042] The current signals of the I and Q channels enter the first and second input terminals of the transimpedance amplifier processing module 7 respectively, are converted into voltage signals by the transimpedance amplifier processing module 7, are converted into voltage signals by the A / D acquisition card module 8, and enter the digital signal processing module 9. The digital signal processing module 9 performs fast Fourier transform and IQ demodulation to obtain the magnitude and direction of the apparent wind speed. The calculation result of the apparent wind speed is displayed and stored in real time by the display and storage module 10.

Claims

1. A homodyne detection Doppler wind measurement laser radar device based on silicon photonic chip, characterized in that: include: Light source module (1), optoelectronic chip module (2), semiconductor optical amplifier (3), erbium-doped fiber amplifier (4), optical circulator (5), optical transceiver antenna (6), transimpedance amplifier processing module (7), A / D acquisition card module (8), digital signal processing module (9) and display and storage module (10); The output end of the light source module (1) is connected to the first input end of the optoelectronic chip module (2), the optical signal output end of the optoelectronic chip module (2) is connected to the input end of the semiconductor optical amplifier (3), the output end of the semiconductor optical amplifier (3) is connected to the input end of the erbium-doped fiber amplifier (4), the output end of the erbium-doped fiber amplifier (4) is connected to the first port of the optical circulator (5); the optical transceiver antenna (6) is connected to the second port of the optical circulator (5) for transmitting and receiving signal light, and the optical circulator The third port of the actuator (5) is connected to the second input end of the optoelectronic chip module (2) and is used to input the received signal light into the optoelectronic chip module (2). The optoelectronic chip module is used to perform coherent detection on the received signal light and convert it into a current signal. The electrical signal output port of the optoelectronic chip module (2) outputs two electrical signals respectively, which enter the digital signal processing module (9) through the transimpedance amplifier processing module (7) and the A / D acquisition card module (8) in sequence. The digital signal processing module (9) is connected to the display and storage module (10).

2. The homodyne detection Doppler wind laser radar device based on silicon photonic chip according to claim 1 is characterized in that: The light source module (1) comprises a laser chip (1-1), a first lens (1-2), an isolator (1-3), a polarizing plate (1-4), a second lens (1-5), a backlight detector (1-6) and a temperature sensor (1-7); the laser chip (1-1) emits a laser beam, which is collimated by the first lens (1-2) and then incident on the isolator (1-3), and then reaches the polarizing plate (1-4) after passing through the isolator (1-3). The beam becomes linearly polarized light after passing through the polarizing plate (1-4), and then is focused by the second lens (1-5) and then input into the optoelectronic chip module (2); the backlight detector (1-6) is used to detect the power of the beam emitted backward by the laser chip (1-1), and the temperature sensor (1-7) is used to detect the working temperature of the laser chip (1-1).

3. The homodyne detection Doppler wind laser radar device based on silicon photonic chip according to claim 2 is characterized in that: The laser emitted by the light source module (1) is continuous linearly polarized seed light, and the laser wavelength is in the near-infrared band that is safe for human eyes. The isolator (1-3) is used to isolate the reflected laser to prevent it from affecting the normal operation of the laser chip (1-1).

4. The homodyne detection Doppler wind laser radar device based on silicon photonic chip according to claim 1, characterized in that: The optoelectronic chip module (2) comprises a first end face coupler (2-1), a second end face coupler (2-2), a third end face coupler (2-3), a beam splitter (2-4), a 90° optical mixer (2-5), a first photodetector (2-6), a second photodetector (2-7), a third photodetector (2-8) and a fourth photodetector (2-9); The laser light emitted by the light source module (1) enters the beam splitter (2-4) after being incident on the first end face coupler (2-1), and is divided into two output paths in the beam splitter (2-4), one light beam is used as the local oscillation light and is input into the first input end of the 90° optical mixer (2-5), and the other light beam is input into the semiconductor optical amplifier (3) through the second end face coupler (2-2); The backscattered signal light is received by the optical transceiver antenna (6), outputted through the third port of the optical circulator (5), and incident on the second input end of the 90° optical mixer (2-5) through the third end face coupler (2-3). The 90° optical mixer (2-5) generates four output signals, which are respectively inputted into the first photodetector (2-6), the second photodetector (2-7), the third photodetector (2-8) and the fourth photodetector (2-9) for photoelectric conversion and beat frequency, thereby forming two current signals which are outputted to the transimpedance amplifier processing module (7).

5. The homodyne detection Doppler wind laser radar device based on silicon photonic chip according to claim 4 is characterized in that: The beam splitter (2-4) is used to input a small portion of the laser energy into the first input end of the 90° optical mixer (2-5) as local oscillator light, and output the remaining laser energy through the second end face coupler (2-2), chopped into pulse light by the semiconductor optical amplifier (3), amplified by the erbium-doped fiber amplifier (4), and then emitted into the atmosphere by the optical transceiver antenna (6) through the optical circulator (5).

6. The homodyne detection Doppler wind laser radar device based on silicon photonic chip according to claim 4, characterized in that: The 90° optical mixer (2-5) is used to mix the local oscillator light with the signal light to generate 4 output optical signals, wherein the local oscillator light has a 90° phase difference (0°, 90°, 180°, 270°), the 0° and 180° signals enter the first photodetector (2-6) and the second photodetector (2-7) for photoelectric conversion and beat frequency to form an I channel, and the 90° and 270° signals enter the third photodetector (2-8) and the fourth photodetector (2-9) for photoelectric conversion and beat frequency to form a Q channel.

7. The homodyne detection Doppler wind laser radar device based on silicon photonic chip according to claim 6, characterized in that: The beat frequency signals corresponding to the I channel and the Q channel have a phase difference of 90°, which are used for IQ demodulation to determine the positive or negative of the Doppler frequency shift, thereby determining the direction of the apparent wind speed.

8. The homodyne detection Doppler wind laser radar device based on silicon photonic chip according to claim 1, characterized in that: The semiconductor optical amplifier (3) is a cascaded SOA chip used for performing high extinction ratio pulse modulation on seed light.

9. The homodyne detection Doppler wind laser radar device based on silicon photonic chip according to claim 6, characterized in that: The transimpedance amplifier processing module (7) further comprises a first transimpedance amplifier chip and a second transimpedance amplifier chip, which are respectively used to convert the current signals output by the I channel and the Q channel into voltage signals for subsequent signal processing.

10. The homodyne detection Doppler wind laser radar device based on silicon photonic chip according to claim 6, characterized in that: The A / D acquisition card module (8) further comprises a first A / D acquisition card and a second A / D acquisition card, which are respectively used to perform analog-to-digital conversion on the electrical signals output by the I channel and the Q channel; the digital signal processing module (9) is used to process the converted digital signals to obtain the magnitude and direction information of the wind speed.

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