Passive focal plane array laser radar coherent receiving module and laser radar system

Abstract

The invention discloses a passive focal plane array laser radar coherent receiving module and a laser radar system, and belongs to the field of laser radars and optical waveguide integrated devices. The problem that an existing laser radar point-to-point receiving mode is complex to implement is solved. A signal receiving end of each photoelectric conversion device is connected with a bus waveguide, each bus waveguide is connected with N resonant ring wavelength filters, and each resonant ring wavelength filter is connected with a receiving optical antenna; m * N receiving optical antennas form an antenna array; the upper side of the antenna array is provided with an off-chip lens, and the off-chip lens is used for focusing the signal light at different angles on the surface of the receiving optical antenna at the corresponding position. The method is suitable for laser radar optical signal receiving.

Description

Technical Field

[0001] The invention belongs to the field of laser radar and optical waveguide integrated devices. Background Art

[0002] With the rapid development of LiDAR technology, photon-integrated optical phase arrays (OPA) have become one of the key technologies for achieving large-scale two-dimensional scanning. At present, combining phase tuning with wavelength tuning has been proven to be the most effective way to achieve efficient two-dimensional scanning. This combination not only improves scanning accuracy, but also expands the application range of LiDAR. However, despite the significant progress made in scanning capabilities by OPA technology, many receiving systems still rely on point-to-point reception. This approach limits the expansion of system scale and increases the complexity of design and implementation. In addition, the point-to-point reception method requires a large number of phase shifters to implement, which means that a large number of external circuits must be introduced for control. This not only increases the complexity of the photonic chip, but also increases the design complexity of the external circuit board. Therefore, how to optimize the design of the receiving system while maintaining efficient two-dimensional scanning capabilities has become a challenge that needs to be solved in the field of LiDAR. Summary of the invention

[0003] The present invention aims to solve the problem of complicated implementation of the existing radar point-to-point receiving mode, and now provides a passive focal plane array laser radar coherent receiving module and a laser radar system.

[0004] The passive focal plane array laser radar coherent receiving module of the present invention comprises: an off-chip lens, a receiving optical antenna, a resonant ring wavelength filter and M photoelectric conversion devices;

[0005] The signal receiving end of each photoelectric conversion device is connected to a bus waveguide, each bus waveguide is connected to N resonant ring wavelength filters, and each resonant ring wavelength filter is connected to a receiving optical antenna;

[0006] M×N receiving optical antennas constitute an antenna array;

[0007] An off-chip lens is arranged on the upper side of the antenna array, and the off-chip lens is used to focus signal lights of different angles on the surface of the receiving optical antenna at the corresponding position of the antenna array.

[0008] Furthermore, in the present invention, the signal output end of each photoelectric conversion device is also connected to two metal electrodes to send out the electrical signal output by the photoelectric conversion device.

[0009] A passive focal plane array laser radar coherent receiving module, comprising: an off-chip lens, a receiving optical antenna, a resonant ring wavelength filter, a photoelectric conversion device, an intrinsic light receiving antenna, a power beam splitter and P coherent mixers;

[0010] The signal output end of each coherent mixer is connected to K photoelectric conversion devices;

[0011] One signal input end of each coherent mixer is connected to the bus waveguide, and the other signal input end is connected to the intrinsic light receiving antenna through the power beam splitter, and the intrinsic light receiving antenna is used to receive the intrinsic light signal;

[0012] Each bus waveguide is connected to Q resonant ring wavelength filters, and each resonant ring wavelength filter is connected to a receiving optical antenna;

[0013] P×Q receiving optical antennas constitute an antenna array;

[0014] An off-chip lens is arranged on the upper side of the antenna array, and the off-chip lens is used to focus signal lights of different angles on the surface of the receiving optical antenna at the corresponding position of the antenna array.

[0015] Furthermore, in the present invention, K is 3 or 4 times of P.

[0016] The laser radar system is implemented based on the passive focal plane array laser radar coherent receiving module, and also includes: a laser radar transmitting module, a tunable laser, a time information control module, a wavelength information control module, a laser radar receiving module and a signal processing module;

[0017] The tunable laser is used to generate laser signals of different wavelengths and transmit the generated laser signals to the laser radar transmitting module;

[0018] The laser radar transmitting module transmits the received laser signal to the target object, and the optical signal reflected by the target object is received by the passive focal plane array laser coherent receiving module;

[0019] The time information control module is used to control the time when the tunable laser outputs the laser; at the same time, the time information of the output laser is transmitted to the signal processing module;

[0020] The wavelength information control module is used to control the tunable laser to output a laser of a corresponding wavelength, and send the wavelength information output by the laser to the signal processing module; the passive focal plane array laser radar coherent receiving module also receives the intrinsic light emitted by the tunable laser; performs coherent mixing on the received intrinsic light and the optical signal reflected by the target object, and sends the mixed signal to the signal processing module;

[0021] The signal processing module uses the time information of the output laser, the wavelength information of the laser output and the mixed signal, and adopts a combined laser ranging signal processing method of analog domain timing and digital domain timing to calculate the distance between the laser radar and the target object.

[0022] Furthermore, in the present invention, the laser radar transmitting module adopts an OPA laser radar transmitting module.

[0023] The passive focal plane array lidar coherent receiving module and lidar described in the present application can realize the reception and detection of single point, multi-point and even one-dimensional arrays through time division multiplexing technology and space division multiplexing technology, while ensuring high reception accuracy and efficiency while reducing the complexity of the overall device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of the first passive focal plane array laser radar coherent receiving module of the present invention;

[0025] Figure 2 Schematic diagram of transmittance curves of single-ring resonant rings with different structures in the embodiments;

[0026] Figure 3 This is a schematic structural diagram of a second passive focal plane array laser radar coherent receiving module according to the present invention;

[0027] Figure 4 This is a principle block diagram of the laser radar system described in the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0029] Specific implementation method 1: refer to Figure 1 and Figure 2 Specifically describing this embodiment, the passive focal plane array laser radar coherent receiving module described in this embodiment includes: an off-chip lens 10, a receiving optical antenna 11, a resonant ring wavelength filter 12 and M photoelectric conversion devices 13;

[0030] The signal receiving end of each photoelectric conversion device 13 is connected to a bus waveguide, each bus waveguide is connected to N resonant ring wavelength filters 12, and each resonant ring wavelength filter 12 is connected to a receiving optical antenna 11;

[0031] M×N receiving optical antennas 11 constitute an antenna array;

[0032] An off-chip lens 10 is disposed on the upper side of the antenna array, and the off-chip lens 10 is used to focus signal lights at different angles onto the surface of the receiving optical antenna 11 at the corresponding position of the antenna array.

[0033] Furthermore, in this embodiment, the signal output end of each photoelectric conversion device 13 is also connected to two metal electrodes to send out the electrical signal output by the photoelectric conversion device 13 .

[0034] Specific implementation method 2: refer to Figure 3 Specifically describing this embodiment, a coherent receiving module of a passive focal plane array laser radar includes: an off-chip lens 10, a receiving optical antenna 11, a resonant ring wavelength filter 12, a photoelectric conversion device 13, an intrinsic light receiving antenna 30, a power beam splitter 31 and P coherent mixers 32;

[0035] The signal output end of each coherent mixer 32 is connected to K photoelectric conversion devices 13;

[0036] One signal input end of each coherent mixer 32 is connected to the bus waveguide, and the other signal input end is connected to the intrinsic light receiving antenna 30 through the power beam splitter 31, and the intrinsic light receiving antenna 30 is used to receive the intrinsic light signal;

[0037] Each bus waveguide is connected to Q resonant ring wavelength filters 12, and each resonant ring wavelength filter 12 is connected to a receiving optical antenna 11;

[0038] P×Q receiving optical antennas 11 constitute an antenna array;

[0039] An off-chip lens 10 is disposed on the upper side of the antenna array, and the off-chip lens 10 is used to focus signal lights at different angles onto the surface of the receiving optical antenna at the corresponding position of the antenna array.

[0040] Furthermore, in this embodiment, K is 3 or 4 times of P.

[0041] Specific implementation method three: refer to Figure 4 Specifically describing this embodiment, the laser radar system is implemented based on the passive focal plane array laser radar coherent receiving module described in the second embodiment, and also includes: a laser radar transmitting module 2, a tunable laser 3, a time information control module 4, a wavelength information control module 5, a laser radar receiving module and a signal processing module 6;

[0042] The tunable laser 3 is used to generate laser signals of different wavelengths and transmit the generated laser signals to the laser radar transmitting module 2;

[0043] The laser radar transmitting module 2 transmits the received laser signal to the target object, and the optical signal reflected by the target object is received by the passive focal plane array laser coherent receiving module;

[0044] The time information control module 4 is used to control the time when the tunable laser 3 outputs the laser; at the same time, the time information of the output laser is transmitted to the signal processing module 6;

[0045] The wavelength information control module 5 is used to control the tunable laser 3 to output a laser of a corresponding wavelength, and send the wavelength information output by the laser to the signal processing module 6;

[0046] The passive focal plane array laser radar coherent receiving module also receives the intrinsic light emitted by the tunable laser; performs coherent mixing on the received intrinsic light and the optical signal reflected by the target object, and sends the mixed signal to the signal processing module 6;

[0047] The signal processing module 6 uses the time information of the output laser, the wavelength information of the laser output and the mixed signal to calculate the distance between the laser radar and the target object using a combined laser ranging signal processing method of analog domain timing and digital domain timing.

[0048] Furthermore, in this embodiment, the laser radar transmitting module 2 adopts an OPA laser radar transmitting module.

[0049] The laser radar transmitting module 2 described in the present invention not only adopts the OPA laser radar transmitting module, but also can adopt the FPSA or MEMS laser radar module.

[0050] This embodiment provides a passive focal plane array laser radar coherent receiving module for time-of-flight ranging method, including an off-chip lens group 10, a receiving optical antenna array 11, a resonant ring wavelength filter array 12 and a photoelectric conversion device 13, such as Figure 1 As shown, the number of receiving optical antennas in the receiving optical antenna array is consistent with the number of resonant ring wavelength filters, the number of photoelectric conversion devices is consistent with the number of rows of the optical antenna array, and the transmission angle is in a one-to-one correspondence with the receiving antenna array.

[0051] The center wavelength of the resonant ring wavelength filter in each column is consistent. In order to prevent the deviation of the center wavelength due to manufacturing errors, a double ring resonant ring or other wide wavelength resonant ring can be selected, such as Figure 2 Shown are the transmittance curves of single-ring and dual-ring resonant ring filters.

[0052] The laser radar receiving module for time-of-flight ranging provided in this embodiment supports single-point reception, multi-point reception and one-dimensional array reception modes.

[0053] In the one-dimensional array receiving mode, the position of the receiving antenna array and the center wavelength of the resonant ring filter are pre-set according to the transmitting system. The scanning mode of the transmitting system in the x direction is wavelength modulation, and the scanning mode in the y direction is phase modulation. One-dimensional array reception is only for array reception in the y direction, and its basic process is as follows:

[0054] (1) The receiving angle of the off-chip lens group is θ1~θ m , a signal light with a wavelength of λ1, focusing the signal light at all grating couplers in the first column according to the relationship between the incident angle and the focus point position designed in advance;

[0055] (2) Since the center wavelength of the resonant ring filter has been set to λ1, the received focused light will normally be coupled into the waveguide bus of each row through the resonant ring;

[0056] (3) The light in the bus waveguide continues to be transmitted to all photoelectric converters, realizing the conversion of optical signals into electrical signals and importing them into subsequent circuits and signal systems, completing the angle θ1~θ m , receiving signal light with wavelength λ1;

[0057] (4) When the receiving angle of the off-chip lens group is θ1~θ m , when the signal light has a wavelength of λn, the signal light is focused on all the grating couplers in the mth column according to the relationship between the incident angle and the focus point position designed in advance;

[0058] (5) Similarly, since the center wavelength of the resonant ring filter has been set to λn, the received focused light will normally be coupled into the waveguide bus of each row through the resonant ring; and for the resonant ring filters of other columns, their center wavelengths are not equal to λn, which makes it possible for the light in the waveguide bus to not leak when passing through the resonant rings of other columns;

[0059] (6) The light in the bus waveguide continues to be transmitted to all photoelectric converters, realizing the conversion of optical signals into electrical signals and importing them into subsequent circuits and signal systems, completing the angle θ1~θ m , signal light with wavelength λn is received.

[0060] By repeating the above steps, the one-dimensional array scanning signal light can be received.

[0061] The embodiment of the present application provides a laser radar receiving module for frequency modulated continuous wave ranging method, including an off-chip lens group 10, a receiving optical antenna array 11, a resonant ring wavelength filter array 12, an intrinsic light receiving antenna 30, a power beam splitter 31, a coherent mixer 32 and a photoelectric conversion device 13, and its planar structure schematic diagram is shown as follows Figure 3As shown. The number of receiving optical antenna arrays is consistent with the number of resonant ring wavelength filter arrays, and the number of photoelectric conversion devices is 3 (using 120-degree coherent mixers) or 4 (using 90-degree coherent mixers) times the number of coherent mixers. The number of final ports of the beam splitter is the same as the number of rows of the receiving optical antenna array. The center wavelength of the resonant ring wavelength filter in each column is consistent.

[0062] Taking the 120-degree coherent mixer and one-dimensional array receiving mode as an example, the basic process is as follows:

[0063] (1) The receiving angle of the off-chip lens group is θ1~θ m , a signal light with a wavelength of λ1, and focusing the signal light at all grating couplers in the first column according to the relationship between the pre-designed angle and the focus point position;

[0064] (2) Since the center wavelength of the resonant ring filter has been set to λ1, the received focused light will normally be coupled into the waveguide bus of each row through the resonant ring;

[0065] (3) In parallel with steps 1 and 2, the intrinsic light receiving antenna couples the intrinsic light of the corresponding wavelength into the waveguide layer, which is equally divided into M beams of waveguide mode field light by a beam splitter and transmitted synchronously with the signal light in the bus waveguide;

[0066] (4) The intrinsic light and signal light of each row are simultaneously input into the 120-degree coherent mixer and output from the three output ports on the left after coherent mixing;

[0067] (5) The mixed signal light of the three ports is continuously transmitted to all photoelectric converters to realize the conversion of optical signal to electrical signal and import it into the subsequent circuit and signal system, completing the angle θ1~θ m , receiving the signal light with a wavelength of λn, and repeating the above steps to realize the reception of the one-dimensional array scanning signal light.

[0068] The focal plane laser radar receiving module provided in the embodiment of the present application has the following main advantages:

[0069] (1) It is not limited to receiving single-point signals, but can receive multi-point or one-dimensional array signals;

[0070] (2) Relatively few photoelectric conversion devices are required, and no active devices are required except for the photoelectric conversion devices, which has obvious low complexity;

[0071] (3) Coherent mixing detection can be used for reception, which has a higher signal-to-noise ratio and a longer detection range.

[0072] The passive focal plane array laser radar receiving module provided in the embodiment of the present application can be combined with a two-dimensional OPA laser radar transmitting module using wavelength and phase tuning to form a complete laser radar system for single-point or one-dimensional array signal light detection. Figure 4 The specific steps are as follows:

[0073] (1) The laser emits a laser signal with a wavelength of λ1 at time t1 under the drive of the time information control module and the wavelength information control module;

[0074] (2) The emitted laser signal passes through the laser radar transmitting module and then emits a single point laser / array laser at an angle θ to the target object;

[0075] (3) After the signal light is reflected by the target object, it is incident on the off-chip lens group of the laser radar receiving module and converges to a single / entire array of grating couplers at a position corresponding to the angle θ and the wavelength λ1;

[0076] (4) The photoelectric conversion device performs photoelectric conversion on the received optical signal and sends it to the signal processing module to extract the signal and determine the distance and speed of the target. The angle in the x direction is identified by the wavelength, and the angle in the y direction is identified by the focus position. In this way, the scanning and detection of two-dimensional light beams can be realized based on the combination of wavelength division multiplexing and space division multiplexing technology.

[0077] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. A passive focal plane array laser radar coherent receiving module, characterized in that: include: An off-chip lens (10), a receiving optical antenna (11), a resonant ring wavelength filter (12), and M photoelectric conversion devices (13); The signal receiving end of each photoelectric conversion device (13) is connected to a bus waveguide, each bus waveguide is connected to N resonant ring wavelength filters (12), and each resonant ring wavelength filter (12) is connected to a receiving optical antenna (11); M×N receiving optical antennas (11) form an antenna array; An off-chip lens (10) is arranged on the upper side of the antenna array, and the off-chip lens (10) is used to focus signal light at different angles onto the surface of a receiving optical antenna (11) at a corresponding position of the antenna array.

2. The passive focal plane array laser radar coherent receiving module according to claim 1, characterized in that: The signal output end of each photoelectric conversion device (13) is also connected to two metal electrodes.

3. A passive focal plane array laser radar coherent receiving module, characterized in that: include: An off-chip lens (10), a receiving optical antenna (11), a resonant ring wavelength filter (12), a photoelectric conversion device (13), an intrinsic light receiving antenna (30), a power beam splitter (31) and P coherent mixers (32); The signal output end of each coherent mixer (32) is connected to K photoelectric conversion devices (13); One signal input end of each coherent mixer (32) is connected to the bus waveguide, and the other signal input end is connected to the intrinsic light receiving antenna (30) through the power beam splitter (31), and the intrinsic light receiving antenna (30) is used to receive the intrinsic light signal; Each bus waveguide is connected to Q resonant ring wavelength filters (12), and each resonant ring wavelength filter (12) is connected to a receiving optical antenna (11); P×Q receiving optical antennas (11) form an antenna array; An off-chip lens (10) is arranged on the upper side of the antenna array, and the off-chip lens (10) is used to focus signal light at different angles on the surface of the receiving optical antenna at a corresponding position of the antenna array.

4. The passive focal plane array laser radar coherent receiving module according to claim 3, characterized in that: K is 3 or 4 times P.

5. A laser radar system, implemented based on the passive focal plane array laser radar coherent receiving module, characterized in that: Also includes: A laser radar transmitting module (2), a tunable laser (3), a time information control module (4), a wavelength information control module (5), a laser radar receiving module and a signal processing module (6); The tunable laser (3) is used to generate laser signals of different wavelengths and transmit the generated laser signals to the laser radar transmitting module (2); The laser radar transmitting module (2) transmits the received laser signal to the target object, and the optical signal reflected by the target object is received by the passive focal plane array laser coherent receiving module; The time information control module (4) is used to control the time when the tunable laser (3) outputs laser light; and transmits the time information of the output laser light to the signal processing module (6); The wavelength information control module (5) is used to control the tunable laser (3) to output laser light of corresponding wavelength, and to send the wavelength information output by the laser to the signal processing module (6); The passive focal plane array laser radar coherent receiving module also receives the intrinsic light emitted by the tunable laser; performs coherent mixing on the received intrinsic light and the optical signal reflected by the target object, and sends the mixed signal to the signal processing module (6); The signal processing module (6) uses the time information of the laser output, the wavelength information of the laser output and the mixed signal to calculate the distance between the laser radar and the target object by adopting a combined laser ranging signal processing method of analog domain timing and digital domain timing.

6. The laser radar system according to claim 5, characterized in that: The laser radar transmitting module (2) adopts an OPA laser radar transmitting module.

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