Passive focal plane array lidar coherent receiving module and lidar system

Abstract

The application discloses a passive focal plane array laser radar coherent receiving module and a laser radar system, and belongs to the field of laser radar and optical waveguide integrated devices. The application solves the problem of complex implementation of the existing laser radar point-to-point receiving mode. A bus waveguide is connected to the signal receiving end of each photoelectric conversion device, N resonant ring wavelength filters are connected to each bus waveguide, and one receiving optical antenna is connected to each resonant ring wavelength filter; MxN receiving optical antennas form an antenna array; an off-chip lens is arranged on the upper side of the antenna array, and the off-chip lens is used for focusing signal light of different angles on the surface of the corresponding receiving optical antenna. The application is suitable for laser radar optical signal receiving.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of laser radar and optical waveguide integrated devices. BACKGROUND

[0002] With the rapid development of laser radar technology, photonic integrated optical phased array (OPA) has become one of the key technologies to realize large-scale two-dimensional scanning. At present, the combination of phase tuning and wavelength tuning has been proved to be the most effective method to realize efficient two-dimensional scanning. This combination not only improves the scanning accuracy, but also expands the application range of laser radar. However, although the OPA technology has made significant progress in scanning capability, many receiving systems still rely on point-to-point receiving method. This method limits the expansion of system scale and increases the complexity of design and implementation. In addition, the point-to-point receiving method requires a large number of phase shifters to be implemented, which means that a large number of additional circuits must be introduced for control. This not only increases the complexity of the photonic chip, but also increases the design complexity of the additional circuit board. Therefore, how to optimize the design of the receiving system while maintaining efficient two-dimensional scanning capability has become a challenge in the field of laser radar. SUMMARY

[0003] The present application is to solve the problem of complex implementation of the existing radar point-to-point receiving method, and 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 provided by the present application 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, and N resonant ring wavelength filters are connected to each bus waveguide, and each resonant ring wavelength filter is connected to a receiving optical antenna.

[0006] The MxN receiving optical antennas form an antenna array.

[0007] The upper side of the antenna array is provided with an off-chip lens, and the off-chip lens is used to focus signal light of different angles on the surface of the receiving optical antenna at the corresponding position of the antenna array.

[0008] Further, the signal output end of each photoelectric conversion device is also connected to two metal electrodes, and the electrical signal output by the photoelectric conversion device is sent out.

[0009] The passive focal plane array laser radar coherent receiving module comprises 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 with K photoelectric conversion devices;

[0011] One signal input end of each coherent mixer is connected with a bus waveguide, and the other signal input end is connected with an eigenlight receiving antenna through a power splitter, and the eigenlight receiving antenna is used for receiving an eigenlight signal;

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

[0013] The P*Q receiving optical antennas form 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 for focusing signal light of different angles on the surface of the receiving optical antenna at the corresponding position of the antenna array.

[0015] Further, in the application, K is 3 or 4 times of P.

[0016] The laser radar system based on the passive focal plane array laser coherent receiving module further comprises 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 for generating laser signals of different wavelengths, and the generated laser signals are transmitted to the laser radar transmitting module.

[0018] The laser radar transmitting module transmits the received laser signals to a target object, and the light signals reflected by the target object are received by the passive focal plane array laser coherent receiving module.

[0019] The time information control module is used for controlling the time of outputting the laser by the tunable laser, and simultaneously transmitting the time information of the output laser to the signal processing module.

[0020] The wavelength information control module is used for controlling the laser output by the tunable laser to be of a corresponding wavelength, and transmitting the wavelength information of the laser output to the signal processing module; the passive focal plane array laser coherent receiving module also receives eigenlight emitted by the tunable laser; the received eigenlight and the light signals reflected by the target object are subjected to coherent mixing, and the mixed signals are transmitted 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 signals to calculate the distance between the laser radar and the target object by using a combined laser ranging signal processing method of analog domain timing and digital domain timing.

[0022] Furthermore, in this invention, the lidar transmitting module adopts the OPA lidar transmitting module.

[0023] The passive focal plane array lidar coherent receiving module and lidar described in this application can achieve reception and detection of single-point, multi-point, or even one-dimensional arrays through time-division multiplexing and space-division multiplexing technologies, while ensuring high receiving accuracy and efficiency while reducing the overall device complexity. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the first passive focal plane array lidar coherent receiving module described in this invention;

[0025] Figure 2 This is a schematic diagram of the transmittance curves of single-ring resonant rings with different structures in the embodiments.

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

[0027] Figure 4 This is a schematic diagram of the lidar system described in this invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0029] Specific implementation method one: Refer to Figure 1 and Figure 2 This embodiment specifically describes the passive focal plane array lidar coherent receiving module, which includes: an external lens 10, a receiving optical antenna 11, a resonant ring wavelength filter 12, and M photoelectric conversion devices 13.

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

[0031] An antenna array is composed of M×N receiving optical antennas 11;

[0032] The antenna array is provided with an off-chip lens 10 on the upper side, and the off-chip lens 10 is used to focus signal light of different angles on the surface of the receiving optical antenna 11 at the corresponding position of the antenna array.

[0033] Further, in the embodiment, the signal output end of each photoelectric conversion device 13 is also connected with two metal electrodes, and the electrical signal output by the photoelectric conversion device 13 is transmitted out.

[0034] Specific implementation method two: refer to Figure 3 Specifically, the passive focal plane array laser radar coherent receiving module in the embodiment comprises an off-chip lens 10, a receiving optical antenna 11, a resonant ring wavelength filter 12, a photoelectric conversion device 13, an eigenlight receiving antenna 30, a power splitter 31, and P coherent mixers 32.

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

[0036] One signal input end of each coherent mixer 32 is connected with a bus waveguide, and the other signal input end is connected with the eigenlight receiving antenna 30 through the power splitter 31, and the eigenlight receiving antenna 30 is used to receive eigenlight signals.

[0037] Each bus waveguide is connected with Q resonant ring wavelength filters 12, and each resonant ring wavelength filter 12 is connected with one receiving optical antenna 11.

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

[0039] The antenna array is provided with an off-chip lens 10 on the upper side, and the off-chip lens 10 is used to focus signal light of different angles on the surface of the receiving optical antenna at the corresponding position of the antenna array.

[0040] Further, in the embodiment, K is 3 or 4 times of P.

[0041] Specific implementation method three: refer to Figure 4 Specifically, the laser radar system in the embodiment is realized based on the passive focal plane array laser radar coherent receiving module in the specific implementation method two, and further comprises 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 the generated laser signals are transmitted to the laser radar transmitting module 2.

[0043] The laser radar emitting module 2 emits the received laser signal to the target object, and the light 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 for controlling the time when the laser emitted by the tunable laser 3, and transmitting the time information of the output laser to the signal processing module 6;

[0045] The wavelength information control module 5 is used for controlling the laser of corresponding wavelength emitted by the tunable laser 3, and transmitting the wavelength information of the laser to the signal processing module 6;

[0046] The passive focal plane array laser radar coherent receiving module also receives the eigenlight emitted by the tunable laser, and coherently mixes the received eigenlight and the light signal reflected by the target object, and transmits 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 and the mixed signal to calculate the distance between the laser radar and the target object by using the combined laser ranging signal processing method of analog timing and digital timing.

[0048] Further, in the embodiment, the laser radar emitting module 2 uses the OPA laser radar emitting module.

[0049] In the embodiment, the laser radar emitting module 2 not only uses the OPA laser radar emitting module, but also uses the FPSA or MEMS laser radar module.

[0050] The embodiment provides a passive focal plane array laser radar coherent receiving module for time-of-flight ranging method, which comprises 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, as shown in the figure. Figure 1 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 optical antenna arrays, and the emitting angle is in one-to-one correspondence with the receiving antenna array.

[0051] The center wavelengths of the resonant ring wavelength filters in each column are consistent, in order to prevent the center wavelengths from deviating due to manufacturing errors, a double-ring resonant ring or other wide wavelength resonant ring can be selected, as shown in the figure. Figure 2 The transmittance curves of the single-ring and double-ring resonant ring filters are shown in the figure.

[0052] The laser radar receiving module for time-of-flight ranging method provided by the embodiment supports single-point receiving, multi-point receiving and one-dimensional array receiving mode.

[0053] In a one-dimensional array receiving mode, the position of the receiving antenna array and the center wavelength of the resonant ring filter are set in advance according to the transmitting system, and the transmitting system needs to be scanned in the x direction in a wavelength modulation mode and in the y direction in a phase modulation mode. The one-dimensional array receiving is only for the array receiving in the y direction, and the basic flow is as follows:

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

[0055] (2) Since the center wavelength of the resonant ring filter has been set to λ1, the received focused light will normally couple 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, realizes the conversion of the optical signal to the electrical signal, and is introduced into the subsequent circuit and signal system, to complete the receiving of the signal light with the angle of θ1~θ m and the wavelength of λ1;

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

[0058] (5) Similarly, since the center wavelength of the resonant ring filter has been set to λn, the received focused light will normally couple into the waveguide bus of each row. Moreover, for the resonant ring filters of other columns, the center wavelengths are not equal to λn, which makes the light in the waveguide bus 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, realizes the conversion of the optical signal to the electrical signal, and is introduced into the subsequent circuit and signal system, to complete the receiving of the signal light with the angle of θ1~θ m and the wavelength of λn.

[0060] The above steps are repeated to realize the receiving of the one-dimensional array scanning signal light.

[0061] The embodiment of the application provides a laser radar receiving module for a frequency-modulated continuous wave ranging method, which comprises 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 a planar structural schematic diagram is as shown in Figure 3The number of receiving optical antenna arrays and the number of resonant ring wavelength filter arrays are consistent, and the number of photoelectric conversion devices is 3 times (using 120-degree coherent mixers) or 4 times (using 90-degree coherent mixers) the number of coherent mixers. The final port number of the beam splitter is the same as the number of rows of receiving optical antenna arrays. The center wavelengths of the resonant ring wavelength filters in each column are consistent.

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

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

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

[0065] (3) Synchronously with steps 1 and 2, the intrinsic light receiving antenna couples the intrinsic light of the corresponding wavelength into the waveguide layer, and divides it into M waveguide mode fields through the beam splitter, and synchronously transmits with the signal light in the bus waveguide;

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

[0067] (5) The mixed signal light of the three ports continues to be transmitted to all photoelectric conversion devices, realizing the conversion of optical signal to electrical signal and being introduced into the subsequent circuit and signal system, and completing the reception of signal light with an angle of θ1~θ m , and a wavelength of λn. Repeating the above steps can realize the reception of one-dimensional array scanning signal light.

[0068] The focal plane laser radar receiving module provided by the embodiment has the following main advantages:

[0069] (1) Not limited to single-point signal reception, but can receive multi-point or one-dimensional array signals;

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

[0071] (3) The coherent mixing detection method can be used for reception, which has high signal-to-noise ratio and long detection range.

[0072] The passive focal plane array laser radar receiving module provided by the embodiments 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 form 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 driving of the time information control module and the wavelength information control module;

[0074] (2) The emitted laser signal is transmitted to a target object in the form of a single-point laser or an array laser at an angle θ after passing through the laser radar transmitting module;

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

[0076] (4) The photoelectric conversion device sends the received optical signal to the signal processing module after photoelectric conversion to complete the extraction of the signal and determine the distance and speed of the target object and other information. The angle in the x direction is identified by the wavelength, and the angle in the y direction is identified by the focusing position, so that two-dimensional beam scanning and detection can be achieved by combining wavelength division multiplexing and space division multiplexing technologies.

[0077] Although the present application is described herein with reference to particular embodiments, it is to be understood that these examples are merely illustrative of the principles and applications of the present application. It is therefore to be understood that numerous modifications can be made to the illustrative embodiments and that other arrangements can be devised without departing from the spirit and scope of the present application as defined by the appended claims. It is to be understood that the features of the dependent claims can be combined with features of the embodiments described herein other than those specifically recited in the original claims. It is also to be understood that features described in relation to one embodiment can be used in other embodiments.

Claims

1. A passive focal plane array lidar coherent receiving module, characterized in that, It comprises: 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, and N resonant ring wavelength filters (12) are connected to each bus waveguide, 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 of different angles on the surface of the receiving optical antenna (11) at the corresponding position of the antenna array.

2. The passive focal plane array lidar coherent reception module of claim 1, wherein, The signal output end of each photoelectric conversion device (13) is also connected to two metal electrodes.

3. A passive focal plane array lidar coherent receiving module, characterized in that, It comprises: 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 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 a bus waveguide, and the other signal input end is connected to an intrinsic light receiving antenna (30) through a power splitter (31), and the intrinsic light receiving antenna (30) is used to receive an 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 of different angles on the surface of the receiving optical antenna at the corresponding position of the antenna array.

4. The passive focal plane array lidar coherent reception module of claim 3, wherein, K is 3 or 4 times of P.

5. The laser radar system based on the passive focal plane array laser radar coherent receiving module implementation according to any one of claims 1-4, characterized in that, It further comprises: 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 the generated laser signals are transmitted to the laser radar transmitting module (2); The laser radar transmitting module (2) transmits the received laser signals to the target object, and the light signals reflected by the target object are 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; at the same time, the time information of the output laser is transmitted to the signal processing module (6); The wavelength information control module (5) is used to control the tunable laser (3) to output laser of corresponding wavelength, and the wavelength information of the laser output by the laser is sent to the signal processing module (6); The passive focal plane array laser radar coherent receiving module also receives intrinsic light emitted by the tunable laser; the received intrinsic light and the light signals reflected by the target object are coherently mixed, and the mixed signals are sent to the signal processing module (6); 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 by using a combined laser ranging signal processing method of analog domain timing and digital domain timing.

6. The lidar system of claim 5, wherein, The laser radar transmitting module (2) is an OPA laser radar transmitting module.

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