FMCW multi-channel laser radar transmitting and receiving device

Abstract

The utility model provides an FMCW multipath laser radar transmit-receive device comprising a seed light source, a phase-locked loop, a photon integrated chip, an erbium-doped fiber amplifier, a 1 * 4 optical switch, a circulator, a PBS beam splitter and a reflector. The seed light source is used for emitting signal light, and the signal light enters the erbium-doped optical fiber amplifier after passing through the phase-locked loop and the photonic integrated chip and then enters the 1 * 4 optical switch; the 1 * 4 optical switch is coupled with four circulators, a PBS (Phosphate Buffer Solution) and a reflecting mirror so as to correspond to scanning of four spaces, and detected signal light of an object enters the photon integrated chip and then is transmitted into the phase-locked loop for coherence with local oscillation light for signal processing; and the 1 * 4 optical switch is used for switching a scanning space.

Description

Technical Field

[0001] The utility model relates to the technical field of laser radar, in particular to a FMCW multi-channel laser radar transceiver. Background Art

[0002] At present, the application scope of optical fiber amplifiers is very wide, especially in the fields of communications and laser radar. However, in some special occasions, such as realizing multi-channel scanning of laser radar, multiple sets of EDFA modules are required for stable light source output. At this time, there is a great demand for heat dissipation. In this case, due to the influence of actual working temperature and the size of the whole structure, it is difficult to meet the actual needs to use multi-channel EDFA optical fiber amplifiers to achieve multi-channel output.

[0003] For example, Chinese patents CN201611255426 and CN202111248881 have explored the miniaturization and cost reduction of multi-line lidar, but they are still lacking in accuracy and the structure needs to be further streamlined so that lidar can be further promoted and applied. Utility Model Content

[0004] In order to solve the problems of low output power, high heat power consumption and high cost in the multi-channel scanning of existing laser radar technology, the utility model uses existing basic components to propose a new FMCW multi-channel laser radar transceiver structure to further optimize the structure of the laser radar and solve or improve the above problems.

[0005] The specific technical solutions are as follows:

[0006] An FMCW multi-channel laser radar transceiver, comprising: a seed light source phase-locked loop (PLL), a photon integrated chip (PIC), an erbium-doped fiber amplifier (EDFA), a 1x4 optical switch, a (polarization-maintaining) circulator, a PBS beam splitter and a reflector;

[0007] Erbium fiber amplifier, then enters 1x4 optical switch;

[0008] The 1x4 optical switch is coupled with a 4-way circulator, a PBS beam splitter and a reflector to correspond to the scanning of 4 spaces, and the signal light of the detected object is incident back to the photon integrated chip, and then transmitted to the phase-locked loop for signal processing with the local oscillator light;

[0009] The 1x4 optical switch is used for switching of the scanning space.

[0010] First, the basic working principle of the device system is to use a laser with a linear frequency modulation to hit the target through a focusing system. The laser returning from the original path and the reference light from the laser form a basic Michelson interferometer. Since the frequency of the light beam is linearly modulated, the measuring light and the reference light generate a beat frequency. The beat frequency is related to the distance and movement speed of the target. After calculation, the depth and speed information of the target can be obtained. This basic principle is within the scope of the existing technology.

[0011] However, the first improvement of the utility model is that, by introducing a phase-locked loop structure, the frequency and phase of the oscillation signal inside the loop can be controlled by an external reference signal, so that the oscillation signal is synchronized to the reference signal, so that the oscillator frequency (phase) integrated in the PIC can more accurately track the seed source frequency or the frequency of the phase modulation signal.

[0012] In the device of the utility model, the signal light output by the seed light source is incident to the EDFA amplifier after passing through the PLL and PIC, and then through the control of the 1x4 optical switch, the signal light of the detected object is received and incident back to the PIC through the action of the circulator, PBS beam splitter and reflector, and the signal processing is carried out in coherence with the local oscillator light, and the scanning in the first space is completed; after a delay period, the 1x4 optical switch is toggled for the second time, and the signal light of the detected object is received and incident back to the PIC through the action of the circulator, PBS beam splitter and reflector, and the signal processing is carried out in coherence with the local oscillator light, and the scanning in the second space is completed. By analogy, by using 1 seed light source, 1 PLL, 1 EDFA fiber amplifier, 1 1x4 optical switch, 1 PIC, 4 circulators, 4 PBSs, and 4 reflectors, 4-way optical scanning and signal processing can be completed.

[0013] Therefore, further, a spectroscopic element and an optical receiver are provided in the photonic integrated chip; wherein each path of the spectroscopic element corresponds to a 1x4 optical switch to satisfy the function of multi-path scanning.

[0014] The optical splitting element is a 1x4 optical switch or a 1x4 optical splitter.

[0015] Furthermore, a pre-circulator is arranged between the erbium-doped fiber amplifier and the 1×4 optical switch; the pre-circulator provides reference light for the photonic integrated chip via a pre-reflector.

[0016] Furthermore, the seed light source is a semiconductor laser light source with a narrow line width of 1.5 microns and linear frequency modulation.

[0017] Furthermore, the erbium-doped fiber amplifier is a polarization-maintaining fiber amplifier, and an EYDFA fiber amplifier may also be used instead.

[0018] Furthermore, the 1x4 optical switch is a high-speed optical switch at the microsecond level.

[0019] In addition, in the present invention, the circulator is a device with high directional isolation.

[0020] A phase-locked loop is a device that can use an external reference signal to control the frequency and phase of an oscillating signal inside the loop, and both are existing devices.

[0021] Compared with the prior art, the present invention and its preferred solution have at least the following beneficial effects:

[0022] 1. Compared with SOA technology, the use of EDFA amplifier can achieve the effects of low phase noise of the amplified signal, high amplification power, good beam quality and wide linear range;

[0023] Second, the phase-locked loop (PLL) can be used to control the frequency and phase of the oscillation signal inside the loop through an external reference signal, solving the problem of synchronizing the oscillation signal to the reference signal. At the same time, the signal processing between the signal light and the local oscillator light is optimized, so that the signal light and the local oscillator light fed back after scanning the object produce a clearer beat frequency effect;

[0024] 3. By using the (horizontally) arranged 1x4 optical switches, the overall reflection angle can be adjusted by adjusting the reflection angle of each light path, which reduces the influence of the existing laser radar on the galvanometer angle adjustment limit. At the same time, users can select the output quantity and reflection angle of the optical path according to actual needs to achieve a wider optical path output angle. Therefore, the use of 1x4 optical switches can effectively replace the role of the galvanometer in laser radar scanning. The high-performance amplification of signal light is achieved by using EDFA; the signal processing between signal light and local oscillator light is optimized by using the characteristics of the phase-locked loop (PLL); for example, 4 circulators, PBS beam splitters and reflectors can be used to achieve 4-way scanning in the horizontal direction. By analogy, using multiple 1x4 optical switches, corresponding to multiple circulators, multiple PBS beam splitters and multiple reflectors, more spatial scanning can be completed, while reducing the number of EDFA modules required in the laser radar, thereby reducing overall power consumption and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0026] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present utility model;

[0027] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the present utility model;

[0028] Figure 3This is a schematic diagram of the structure of Example 3 of the utility model. DETAILED DESCRIPTION

[0029] In order to make the features and advantages of this patent more obvious and easy to understand, the following embodiments are specifically described in detail with the accompanying drawings as follows:

[0030] like Figure 1 As shown, in the first embodiment of the utility model, a FMCW multi-channel laser radar transceiver system is provided, including a seed light source 100, a photonic integrated chip (PIC) 101, a phase-locked loop (PLL) 102, a signal light receiver 104, an erbium-doped fiber amplifier (EDFA) 105, 1x4 optical switches 103 and 106, a circulator 107 (including 4 independent circulator components), a PBS beam splitter and a reflector 108 (including 4 independent PBS beam splitters and reflectors).

[0031] In this embodiment, after the signal light output by the seed light source 100 passes through the photonic integrated chip (PIC) 101, it is first extracted by the phase-locked loop (PLL) 102 and generates the corresponding signal light frequency, which makes a pre-setting for subsequent data synchronization, clock distribution and frequency adjustment, reduces the phase error, and realizes efficient optimization processing of the feedback signal light, so that the signal light and the local oscillator light fed back after scanning the object produce a clearer beat frequency effect. This part of the function is the inherent function of the phase-locked loop; then the optical switch 103 inside the photonic integrated chip (PIC) 101 is turned to the corresponding wavelength position, and at this time a beam of light enters the pre-designed receiver as the local oscillator The light is preserved, and another beam of light is incident on the EDFA fiber amplifier for signal amplification processing. Under the action of the external 1x4 optical switch 106, the output amplified signal light is transmitted to the outside for scanning and reflection in the relevant space after passing through the circulator 107, and then the light is divided into two paths of light with polarization perpendicular to each other through the PBS beam splitter and the reflector 108: one path of light directly enters the signal light receiver 104 in the photonic integrated chip (PIC) 101, and the other path of light is delayed by the reflector to enter the signal light receiver 104. After being received by the receiver in the PIC, the two paths are coherently transmitted with the local oscillator light through the phase-locked loop (PLL) 102.

[0032] It should be noted that in order to ensure the best working effect, the optical switches 103 and 106 need to be used synchronously during operation to prevent errors in spatial scanning. The four groups of signal optical receivers 104 will work in turn to ensure that each channel maintains a time frame between microseconds and milliseconds to ensure accurate scanning of effective targets. Figure 1The circulator 107 and the PBS beam splitter and the reflector 108 shown in the figure act separately and one to one. Under the action of the 1x4 optical switch, 1 circulator and 1 PBS beam splitter + reflector complete the scanning of a spatial area within an angle. 4 circulators, 4 PBS beam splitters and 4 reflectors can realize 4-way scanning in the horizontal direction. Multiple circulators, PBS beam splitters and reflectors can realize multi-way scanning in the horizontal direction. At the same time, the user can flexibly adjust the overall reflection angle according to actual needs by adjusting the reflection angle of each light path, selecting the appropriate light path output quantity and reflection angle, so as to achieve a wider light path output angle, thereby replacing the role of the galvanometer in the laser radar scanning, which will not be described in detail here. The utility model scheme is based on a 1x4 optical switch, which can divide the continuous incident light into n paths, wherein before each path is newly allocated data, the signal light of the new path needs to be delayed for one cycle before being sent, and the signal processing is performed according to n columns as a subframe, and this processing is continuous, without any waiting in the process. Under the multi-channel scanning mechanism, the effective target will definitely appear completely in a subframe of a certain channel at the first time, and multiple channels will successively contain image subframes with complete target information.

[0033] It should be noted that, based on the system device structure provided by the present invention, the art can obtain the above-mentioned basic operations and setting methods without additional creative work by combining the basic working principles of the above-mentioned components and the conventional design of the prior art (for example, refer to the comparative documents provided in the background technology). Therefore, what the present invention provides is the design of the device structure itself and does not involve improvements or innovations in the working principles or methods of the laser radar.

[0034] As another preferred solution, Figure 2 As shown, in Example 2, the 1x4 optical switch 103 in the PIC is replaced with a 1x4 optical splitter, and the output principle is the same as Figure 1 The structure is the same as Figure 2 The circulator 107 and PBS beam splitter + reflector 108 shown in the demonstration act separately, one to one, and one circulator and one PBS beam splitter + reflector complete the scanning of a spatial area within an angle. To meet the needs of complete spatial scanning, only four circulators and four PBS beam splitters + reflectors are needed to achieve four-way scanning in the horizontal direction. However, this solution requires a higher power seed source to balance the signal processing of the local oscillator light in the receiver to achieve precise scanning, which will not be described in detail here.

[0035] like Figure 3As shown in the figure, as another feasible solution, Example 3 reduces the 1x4 optical switch integrated in the PIC and adds a pre-circulator in front of the 1x4 optical switch to achieve scanning of the entire space. The advantage of this solution is that it can reduce the number of circulators, PBS beam splitters and reflectors used, while reducing the output power of the seed source to achieve scanning of the entire space, which not only reduces unnecessary device losses, but also helps to reduce costs. Its output principle is similar to Figure 1 The structure is the same, and the circulator's characteristics of unidirectional circulation and reverse isolation are utilized. First, the output signal light of the seed light source is processed by the PIC and amplified by the EDFA, and then output to the 1x4 optical switch in a unidirectional manner through the circulator. Then, after the 1x4 optical switch is turned one by one, the signal light is output to the outside to complete the spatial scanning detection. Finally, the signal light of the detected related objects is incident back to the PIC through the circulator, PBS beam splitter, and reflector, and is coherently processed with the local oscillator light. This part of the structure is consistent with the previous two embodiments and will not be described in detail here.

[0036] This patent is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of FMCW multi-channel laser radar transceiver devices under the inspiration of this patent. All equal changes and modifications made according to the scope of the patent application of this utility model should be covered by this patent.

Claims

1. A FMCW multi-channel laser radar transceiver, characterized in that: include: Seed light source, phase-locked loop, photonic integrated chip, erbium-doped fiber amplifier, 1x4 optical switch, circulator, PBS beam splitter and reflector; The seed light source is used to emit signal light, which, after passing through a phase-locked loop and a photon integrated chip, is incident on an erbium-doped fiber amplifier and then enters a 1x4 optical switch; The 1x4 optical switch is coupled with a 4-way circulator, a PBS beam splitter and a reflector to correspond to the scanning of 4 spaces, and the signal light of the detected object is incident back to the photon integrated chip, and then transmitted to the phase-locked loop for signal processing with the local oscillator light; The 1x4 optical switch is used for switching of the scanning space.

2. The FMCW multi-channel laser radar transceiver according to claim 1, characterized in that: The photonic integrated chip is provided with a light splitting element and a light receiver; wherein each path of the light splitting element corresponds to a 1x4 optical switch.

3. The FMCW multi-channel laser radar transceiver according to claim 2, characterized in that: The optical splitting element is a 1x4 optical switch or a 1x4 optical splitter.

4. The FMCW multi-channel laser radar transceiver according to claim 1, characterized in that: A pre-circulator is arranged between the erbium-doped fiber amplifier and the 1x4 optical switch; the pre-circulator provides reference light for the photon integrated chip via a pre-reflector.

5. The FMCW multi-channel laser radar transceiver according to claim 1, characterized in that: The seed light source is a semiconductor laser light source with a narrow line width of 1.5 microns and linear frequency modulation.

6. The FMCW multi-channel laser radar transceiver according to claim 1, characterized in that: The erbium-doped fiber amplifier is a polarization-maintaining fiber amplifier.

7. The FMCW multi-channel laser radar transceiver according to claim 1, characterized in that: The 1x4 optical switch is a high-speed optical switch at the microsecond level.

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