CN-116413689-B - Coaxial receiving and transmitting laser radar and optical chip

CN116413689BCN 116413689 BCN116413689 BCN 116413689BCN-116413689-B

Abstract

The application provides a coaxial receiving and transmitting laser radar and an optical chip. The laser radar comprises a laser light source, a first optical coupler, a second optical coupler, a coaxial optical transceiver unit, a coherence cancellation unit, a detection unit and a signal processing unit. The laser light source divides the generated laser signal into signal light and local oscillation light through the first optical coupler, the local oscillation light enters the coherent cancellation unit, and the signal light is emitted from the coaxial light receiving and transmitting unit through the second optical coupler and is received by the coaxial light receiving and transmitting unit as reflected light. The reflected light and the interference light generated by the coaxial light receiving and transmitting unit enter the coherence cancellation unit through the second optical coupler. After the interference light is eliminated by the coherent cancellation unit through the local oscillation light, the local oscillation light and the reflected light are sent to the signal processing unit through the detection unit so as to calculate the related information of the obstacle. The technical scheme provided by the application can eliminate the influence of interference light on reflected light in a radar light path system, improve the ranging precision of the laser radar and ensure the normal work of the laser radar.

Inventors

ZHANG LEI
XU YANG
ZHANG ENGE
YANG TONGXIN
DENG YONGQIANG

Assignees

武汉万集光电技术有限公司

Dates

Publication Date: 20260505
Application Date: 20211230

Claims (11)

1. The coaxial receiving and transmitting laser radar is characterized by comprising a laser light source, a first optical coupler, a second optical coupler, a coaxial light receiving and transmitting unit, a coherence cancellation unit, a detection unit and a signal processing unit; the laser light source is used for generating a laser signal; The first optical coupler is used for dividing the laser signal into signal light and local oscillator light, sending the signal light to the second optical coupler and sending the local oscillator light to the coherence cancellation unit; the second optical coupler is configured to send the signal light to the coaxial optical transceiver, receive reflected light and interference light returned by the coaxial optical transceiver, and send the reflected light and the interference light to the coherence cancellation unit; The coaxial light receiving and transmitting unit is used for transmitting the signal light to an obstacle and receiving the reflected light returned by the obstacle; the coaxial light receiving and transmitting unit generates the interference light in the process of transmitting the signal light to the obstacle; the coherent cancellation unit is used for performing coherent cancellation on the interference light by using the local oscillation light to eliminate the interference light, and sending the mixed light of the local oscillation light and the reflected light after coherence to the detection unit, wherein the difference value of the optical paths of the local oscillation light and the interference light from the laser light source to the coherent cancellation unit is within a preset range; The detection unit is used for converting the mixed light into an electric signal; The signal processing unit is used for determining relevant information of the obstacle according to the electric signal.
2. The lidar of claim 1, wherein the coherence cancellation unit comprises a phase shifter and a third optical coupler, The phase shifter is used for shifting the phase of the local oscillation light, and the phase difference N between the phase of the local oscillation light after the shift and the phase difference N between the phase of the interference light 180 Degrees, wherein N is an integer; The third optical coupler is configured to mix the phase-shifted local oscillation light, the reflected light, and the interference light to eliminate the interference light, and send the mixed light to the detection unit.
3. The lidar of claim 2, wherein the laser radar is configured to, When the detection unit is a balance detection unit, the third optical coupler inputs the mixed light into the balance detection unit in two ways, or When the detection unit is a single-ended detection unit, the third optical coupler inputs the mixed light as one path to the detection unit.
4. A laser radar according to any one of claims 1 to 3 wherein the laser light source is a narrow linewidth laser light source and the linewidth of the laser signal emitted by the narrow linewidth laser light source is less than 10MHz.
5. The lidar of any of claims 1 to 3, wherein the second optical coupler comprises a first port, a second port, and a third port, The signal light enters from the first port and exits from the second port; The reflected light and the disturbing light are incident from the second port and exit from the third port.
6. The lidar according to any of claims 1 to 3, wherein the information related to the obstacle includes at least one of distance information, speed information, azimuth information, altitude information, attitude information, and shape information.
7. The laser radar according to any one of claims 1 to 3, wherein the coaxial optical transceiver unit comprises at least one optical antenna or at least one optical phased array system.
8. The lidar according to claim 7, wherein the coaxial light-transmitting-receiving unit further comprises an optical lens group for transmitting and enhancing the signal light and the reflected light.
9. The lidar according to claim 1, wherein the first optical coupler, the second optical coupler, the coaxial optical transceiver unit, the coherence cancellation unit, and the detection unit are integrated on a silicon optical chip to constitute an optical chip.
10. An optical chip is characterized by comprising a first optical coupler, a second optical coupler, a coaxial optical transceiver unit, a coherence cancellation unit and a detection unit, The first optical coupler is used for dividing a laser signal emitted by the laser light source into signal light and local oscillator light, sending the signal light to the second optical coupler and sending the local oscillator light to the coherence cancellation unit; the second optical coupler is configured to send the signal light to the coaxial optical transceiver, receive reflected light and interference light returned by the coaxial optical transceiver, and send the reflected light and the interference light to the coherence cancellation unit; The coaxial light receiving and transmitting unit is used for transmitting the signal light to an obstacle and receiving the reflected light returned by the obstacle; the coaxial light receiving and transmitting unit generates the interference light in the process of transmitting the signal light to the obstacle; the coherent cancellation unit is used for carrying out coherent cancellation on the interference light by using the local oscillation light to eliminate the interference light and sending the mixed light of the local oscillation light and the reflected light after the coherence to the detection unit, wherein the difference value of the optical paths of the local oscillation light and the interference light from the laser light source to the coherent cancellation unit is in a preset range; the detection unit is used for converting the mixed light into an electric signal, and the electric signal is used for determining relevant information of the obstacle.
11. The optical chip of claim 10, wherein the coherence cancellation unit comprises a phase shifter and a third optical coupler, The phase shifter is used for shifting the phase of the local oscillation light, and the phase difference N between the phase of the local oscillation light after the shift and the phase difference N between the phase of the interference light 180 Degrees, wherein N is an integer; The third optical coupler is configured to mix the phase-shifted local oscillation light, the reflected light, and the interference light to eliminate the interference light, and send the mixed light to the detection unit.

Description

Coaxial receiving and transmitting laser radar and optical chip Technical Field The embodiment of the application belongs to the technical field of laser radars, and particularly relates to a coaxial transceiving laser radar and an optical chip. Background The frequency modulation continuous wave (Frequency Modulated Continuous Wave, FMCW) laser radar can emit a laser signal (simply referred to as emission light or signal light) with a linear frequency, and after receiving the laser signal (simply referred to as receiving light or reflected light) reflected by an obstacle, determines related information such as the distance of the obstacle according to the frequency difference between the signal light and the reflected light at the receiving moment, thereby having higher ranging precision. FMCW lidars include parallel axis FMCW lidars and coaxial FMCW lidars. In the coaxial FMCW lidar, the optical paths of the outgoing signal light and the received reflected light in the optical transceiver unit are identical. Because FMCW has extremely high detection sensitivity, if the emitted light produces interference light in the optical path system, the interference light will seriously interfere with the reflected light, which causes inaccurate ranging of the laser radar and even fails to work properly. Disclosure of Invention The embodiment of the application provides a coaxial receiving and transmitting laser radar and an optical chip, which can eliminate interference light generated in an optical path system to a certain extent, improve the accuracy of laser radar ranging and ensure the normal operation of the laser radar. In order to solve the technical problems, the embodiment of the application provides the following technical scheme: In a first aspect, an embodiment of the present application provides a coaxial transceiving laser radar, where the laser radar includes a laser light source, a first optical coupler, a second optical coupler, a coaxial optical transceiving unit, a coherence cancellation unit, a detection unit, and a signal processing unit. And the laser light source is used for generating a laser signal. The first optical coupler is used for dividing the laser signal into signal light and local oscillator light, sending the signal light to the second optical coupler and sending the local oscillator light to the coherence cancellation unit. And the second optical coupler is used for transmitting the signal light to the coaxial light receiving and transmitting unit, receiving the reflected light and the interference light returned by the coaxial light receiving and transmitting the reflected light and the interference light to the coherence cancellation unit. And the coaxial optical transceiver unit is used for transmitting the signal light to the obstacle and receiving the reflected light returned by the obstacle, and the coaxial optical transceiver unit generates interference light in the process of transmitting the signal light to the obstacle. And the coherence cancellation unit is used for performing coherence cancellation processing on the interference light by using the local oscillation light to eliminate the interference light, and sending the mixed light of the coherent local oscillation light and the reflected light to the detection unit, wherein the difference value of the optical paths of the local oscillation light and the interference light from the laser light source to the coherence cancellation unit is within a preset range. And the detection unit is used for converting the mixed light into an electric signal. And the signal processing unit is used for determining relevant information of the obstacle according to the electric signals. The laser radar provided by the embodiment of the application can eliminate the influence of the interference light on the reflected light in a radar light path system by performing phase shift on the local oscillation light and performing coherent processing on the phase-shifted local oscillation light and the interference light, thereby improving the ranging accuracy of the laser radar and ensuring the normal operation of the laser radar. In some embodiments, the coherence cancellation unit includes a phase shifter and a third optical coupler. The phase shifter is used for shifting the phase of the local oscillation light, and the phase difference N between the phase of the local oscillation light after the shift and the phase difference N between the phase of the interference light180 Degrees, wherein N is an integer. And the third optical coupler is used for mixing the phase-shifted local oscillation light, the reflected light and the interference light to eliminate the interference light and transmitting the mixed light to the detection unit. In this embodiment, when the phase of the offset local oscillation light is different from the phase of the interference light by an odd multiple of 180 degrees, the interference light is eliminated by mean