Receiving assembly and laser radar

Abstract

The invention discloses a receiving assembly and a laser radar. The receiving assembly comprises a scanning device and at least one receiving channel; each receiving channel comprises at least one receiving waveguide and at least one grating coupler, the receiving waveguides and the grating couplers are in one-to-one correspondence, and the grating couplers are used for coupling receiving light reflected by the scanning device into the corresponding receiving waveguides; wherein the grating coupler comprises a first grating layer, the first grating layer comprises a plurality of grating units arranged along a first direction, the duty ratio of each grating unit in the plurality of grating units is in a first range, the total length of the plurality of grating units in the first direction is greater than the first length, and the first direction corresponds to the scanning direction of the scanning device. In the receiving assembly, the grating coupler is adopted to couple the receiving light into the receiving waveguide, so that the receiving efficiency of the laser radar can be improved, and meanwhile, the hardware cost and the product size of the laser radar are reduced.

Description

Technical Field

[0001] This application relates to the field of detection technology, and particularly to a receiving component and a lidar. Background Art

[0002] In a lidar, an edge coupler (EC) is generally used to couple received light into a receiving waveguide.

[0003] To achieve a sufficient point frequency, a lidar generally has one or more rapidly rotating scanning devices. The emitted light is emitted through the scanning device, and the received light returns through the scanning device. Since it takes a certain amount of time for the laser to travel from emission to hitting the target and then from the target reflection to reach the receiver, and during this time the scanning device has rotated through a certain angle, there will be a certain deflection angle between the emitted light and the received light, resulting in a transceiver asynchronous effect (also known as the walk-off effect). The position of the deflected received light on the receiving surface of the edge coupler is offset from the ideal receiving position, and may even move out of the receiving surface of the edge coupler, leading to low receiving efficiency and poor detection performance of the lidar.

[0004] One method to cope with the walk-off effect is to increase the number of waveguides in each receiving channel of the lidar to form a waveguide array to increase the equivalent receiving surface of the entire receiver of the lidar, so that the lidar may still detect the optical signal after the received light is deflected. However, this method not only doubles the cost, but also brings great pressure to the processing of the subsequent hardware signals. Moreover, this method can only improve the optical receiving efficiency at a specific deflection angle when the deflection direction of the received light is parallel to the arrangement direction of the multi-waveguides, and the optical receiving efficiency at other deflection angles is still poor. In addition, if multiple waveguides are combined into a single waveguide for reception, the output optical power after combination is much smaller than the input optical power, and the overall optical receiving efficiency is poor.

[0005] How to improve the receiving efficiency of the lidar while taking into account reducing the hardware cost and product size of the lidar is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] This application provides a receiving component and a lidar for improving the receiving efficiency of the lidar while taking into account reducing the hardware cost and product size of the lidar.

[0007] In a first aspect, a receiving component is provided, which can be applied to a lidar. The receiving component includes a scanning device and at least one receiving channel; each receiving channel in the at least one receiving channel includes at least one receiving waveguide and at least one grating coupler, and the receiving waveguides and the grating couplers are in one-to-one correspondence. Each grating coupler in the at least one grating coupler is configured to couple the received light reflected back by the scanning device into the receiving waveguide corresponding to each grating coupler; wherein, the grating coupler includes a first grating layer, the first grating layer includes a plurality of grating units arranged along a first direction, the duty cycle of each grating unit in the plurality of grating units is within a first range, the total length of the plurality of grating units in the first direction is greater than a first length, and the first direction corresponds to (e.g., is parallel to) the scanning direction of the scanning device.

[0008] In the receiving component provided by the embodiments of the present application, a grating coupler is used to couple the received light into the receiving waveguide. The duty cycle of each grating unit in the first grating layer of the grating coupler is within a first range, and the total length of the plurality of grating units in the first direction is greater than a first length. In this way, the total length of the mode field (i.e., the effective receiving surface) of the grating coupler in the first direction is greater than the first length, so that even if the received light is offset due to the walk-off effect, it can still be received by the grating coupler and coupled into the receiving waveguide, improving (or solving) the problem of low receiving efficiency of the lidar caused by the walk-off effect.

[0009] Moreover, in the embodiments of the present application, since the mode field of the grating coupler is large enough, a receiving channel can have at least a combination of one receiving waveguide and one grating coupler at least, and there is no need to add an additional optical transposition system. Therefore, while improving the receiving efficiency of the lidar, the hardware cost and product size of the lidar can be reduced.

[0010] In addition, the position of the grating coupler is relatively flexible and can be located at any position in the lidar chip. Therefore, unnecessary waveguide crossovers can be minimized, and crosstalk between waveguides can be reduced, thereby improving the overall receiving performance of the lidar.

[0011] In a possible design, the first direction corresponds to (e.g., is parallel to) the offset direction of the walk-off effect generated by the scanning device.

[0012] Since the offset direction of the walk-off effect is caused by the scanning of the scanning device, the first direction corresponds to the scanning direction of the scanning device, and it can also be described as the first direction corresponding to the offset direction of the walk-off effect.

[0013] In a possible design, the grating period of each grating unit in the plurality of grating units is within a second range.

[0014] By matching and designing the grating period of the grating coupler, the mode field of the grating coupler can be increased in the offset direction of the walk-off effect.

[0015] In a possible design, the length of the mode field of the grating coupler in the first direction is greater than the first length.

[0016] In this way, it can be ensured that the received light after offset is still projected into the mode field of the grating coupler, so as to improve the reception efficiency of the lidar.

[0017] In a possible design, the first length is related to the maximum offset corresponding to the walk-off effect generated by the scanning device.

[0018] In this way, when the walk-off effect is the most serious, it can be realized that the received light after offset is still projected into the mode field of the grating coupler, so as to improve the reception efficiency of the lidar.

[0019] In a possible design, the scanning device is a one-dimensional scanning device, and the first direction (or the offset direction of the walk-off effect generated by the scanning device) corresponds to (for example, is parallel to) the scanning direction of the scanning device; or, the scanning device is a two-dimensional scanning device, and the first direction (or the offset direction of the walk-off effect generated by the scanning device) corresponds to (for example, is parallel to) the scanning direction of the fast axis in the two-dimensional scanning device.

[0020] In this way, whether it is a one-dimensional scanning device or a two-dimensional scanning device, the problem of low reception efficiency of the lidar caused by the walk-off effect can be improved (or solved).

[0021] In a possible design, the total length of the multiple grating units in the second direction is less than the first length, and the second direction is perpendicular to the first direction. In this way,

[0022] In this way, it can be realized that the mode field of the first grating layer (or the grating coupler) is increased in the offset direction of the walk-off effect, while it can be not increased (or the increment is small) in the second direction. For example, the length of the mode field of the grating coupler in the second direction is less than the first length, so as to minimize the size of the grating coupler while improving the reception efficiency of the first grating layer (or the grating coupler).

[0023] In a possible design, the total length of the multiple grating units in the second direction is equal to the total length of the multiple grating units in the first direction, and the second direction is perpendicular to the first direction.

[0024] In this way, it is possible to increase the mode field of the first grating layer (or the grating coupler) in multiple directions (including the offset direction of the walk-off effect). For example, the length of the mode field of the grating coupler in the second direction is equal to the length of the mode field of the grating coupler in the first direction, further improving the reception efficiency of the first grating layer (or the grating coupler).

[0025] In a possible design, the first grating unit among the multiple grating units is offset relative to the center of the multiple grating units, and the offset direction of the first grating unit relative to the center is the same as the offset direction of the walk-off effect generated by the scanning device; wherein, the duty cycle of the first grating unit is a first value, and the grating period of the first grating unit is a second value.

[0026] In this way, it is possible to achieve a mode field with a peak biased to one side for the first grating layer (or the grating coupler), which can improve the reception efficiency of the first grating layer (or the grating coupler) for the received light after offset.

[0027] In a possible design, the offset amount of the first grating unit relative to the center is related to the maximum offset amount corresponding to the walk-off effect generated by the scanning device.

[0028] In this way, when the walk-off effect is the most severe (i.e., when the offset amount corresponding to the walk-off effect is the maximum), the position of the received light is exactly the peak position, and the reception efficiency of the first grating layer (or the grating coupler) for the received light is the highest.

[0029] In a possible design, the first grating unit among the multiple grating units is located at the center of the multiple grating units; wherein, the duty cycle of the first grating unit is a first value, and the grating period of the first grating unit is a second value.

[0030] In this way, it is possible to achieve a mode field with a peak at the center for the first grating layer (or the grating coupler), and the reception efficiency at the position of the received light before offset is higher.

[0031] In a possible design, the coupling efficiency of the first grating unit is the maximum among the coupling efficiencies of each grating unit in the multiple grating units.

[0032] In a possible design, the duty cycle of each grating unit in the multiple grating units gradually increases or decreases in the direction from the first grating unit to the second grating unit; or, the coupling efficiency of each grating unit in the multiple grating units gradually decreases in the direction from the first grating unit to the second grating unit; wherein, the second grating unit is the first grating unit or the last grating unit in the multiple grating units in the first direction.

[0033] In this way, the mode field of the first grating layer (or the grating coupler) can be a Gaussian spot mode field or a quasi-Gaussian spot mode field. When the spot of the received light is a Gaussian spot or a quasi-Gaussian spot, the mode field distribution of the first grating layer (or the grating coupler) matches the energy distribution of the spot of the received light, which can further improve the reception efficiency of the first grating layer (or the grating coupler).

[0034] In a possible design, the grating coupler further includes a second grating layer disposed above or below the first grating layer.

[0035] In this way, the reception efficiency of the grating coupler can be further improved.

[0036] In a possible design, the grating coupler further includes a reflective layer disposed below the first grating layer, where the reflective layer is a distributed Bragg reflector (DBR) layer or a metal layer.

[0037] In this way, the reception efficiency of the grating coupler can be further improved.

[0038] In a second aspect, a lidar is provided, including the receiving component as described in the first aspect or any possible design of the first aspect.

[0039] Optionally, the lidar further includes a transmitting component.

[0040] Optionally, the transmitting component and the receiving component share a scanning device.

[0041] Optionally, the transmitting component includes a transmitting waveguide and a grating coupler, and the structural parameters of the grating layer in the grating coupler of the transmitting component correspond to the structural parameters of the grating layer in the grating coupler of the receiving component, where the structural parameters include one or more of shape, size, grating period, and duty cycle.

[0042] In a third aspect, a terminal is provided, including the receiving component as described in the first aspect or any possible design of the first aspect, or including the lidar as described in the second aspect or any possible design of the second aspect.

[0043] For the specific designs and beneficial effects of the above second aspect to the third aspect, reference may be made to the corresponding designs and beneficial effects in the first aspect. Description of the Drawings

[0044] Figure 1 is a schematic diagram of the walk-off effect;

[0045] Figure 2 is a schematic diagram of a lidar with a single waveguide structure;

[0046] Figure 3A and Figure 3B is a schematic diagram of a lidar with a multi-waveguide structure;

[0047] Figure 4 is a schematic structural diagram of a receiving component provided by an embodiment of the present application;

[0048] Figure 5 is a schematic structural diagram of the first grating layer 221 of the grating coupler 22 provided by an embodiment of the present application;

[0049] Figures 6A to 6F is a schematic diagram of the mode field of the grating coupler 22 (or the first grating layer 221) provided by an embodiment of the present application;

[0050] Figure 6G is a schematic structural diagram of the first grating layer 221 of the grating coupler 22 provided by an embodiment of the present application;

[0051] Figures 7A to 7C is a schematic structural diagram of the grating coupler 22 provided by an embodiment of the present application;

[0052] Figures 8A to 8D is a schematic diagram of the scanning device 01 of the grating coupler 22 provided by an embodiment of the present application;

[0053] Figure 9 is a schematic structural diagram of a lidar provided by an embodiment of the present application. Detailed implementation manners

[0054] The technical solutions provided by the embodiments of the present application can be applied to devices with laser detection capabilities, such as lidars, or terminal devices with laser detection capabilities. Among them, the terminal device can be an intelligent device with laser detection capabilities, including but not limited to: smart home devices, such as televisions, floor sweeping robots, smart table lamps, audio systems, smart lighting systems, electrical control systems, home background music, home theater systems, intercom systems, video surveillance, etc.; intelligent transportation devices, such as cars, ships, drones, trains, trucks, etc.; intelligent manufacturing devices, such as robots, industrial equipment, intelligent logistics, intelligent factories, etc. Or, the terminal device can also be a computer device with laser detection capabilities, such as a desktop computer, a personal computer, a server, etc. It should also be understood that the terminal device can also be a portable electronic device with laser detection capabilities, such as a mobile phone, a tablet computer, a handheld computer, earphones, speakers, wearable devices (such as smart watches), in-vehicle devices, virtual reality devices, augmented reality devices, etc. Hereinafter, a lidar is taken as an example.

[0055] A lidar can be provided with one or more rapidly rotating scanning devices to increase the point frequency (the point frequency is the total number of detection points obtained by the lidar per second). The scanning devices include a rotating mirror, a micro-electro-mechanical system (MEMS) galvanometer, a Galvo scanning galvanometer, etc. In a lidar with a scanning device, the emitted light is emitted via the scanning device, and the received light returns via the scanning device. Since it takes a certain amount of time for the laser to travel from emission to hitting the target and then from the target to be reflected and reach the receiver, and during this time the scanning device has rotated by a certain angle, there will be a certain deflection angle between the emitted light and the received light.

[0056] As Figure 1 shown, Figure 1 (A) in Figure 1 shows the situation when the emitted light is emitted through the scanning device, Figure 1 (B) in

[0057] shows the situation when the received light is received by the lidar via the scanning device without the scanning device rotating, Figure 1 (C) and (D) in

[0058] show the situation when the received light is received by the lidar via the scanning device with the scanning device rotating. It can be understood that the optical path of the emitted light and the optical path of the received light can be coaxial or non-coaxial. When the optical paths of the emitted light and the received light are coaxial, the transmitter and the receiver can be integrated into one device. When the optical paths of the emitted light and the received light are non-coaxial, the transmitter and the receiver can be realized through two devices respectively. The embodiments of the present application do not make any restrictions.

[0059] However, for lidars with waveguide structures, such as frequency modulated continuous waveform (FMCW) lidars, as Figure 2 shown, their receivers are of the structure of an edge coupler (EC) + receiving waveguide (the waveguide used to receive light is called the receiving waveguide), and the EC couples the received light into the receiving waveguide. For such an EC + receiving waveguide receiver, the size of its receiving surface is limited (on the order of um), and the receiving efficiency is sensitive to the position of the focused spot of the received light. Therefore, the shift in the position of the received light caused by the walk-off effect will lead to a decrease in the receiving efficiency. Moreover, the farther the target distance is and the greater the angular velocity of the scanning device is, the more significant the walk-off effect is, and the more the receiving efficiency of the lidar decreases. It can be understood that Figure 2 only one receiving channel is schematically shown, and there can be multiple receiving channels in actual applications. Figure 2 The main intention is to illustrate that the walk-off effect will cause the receiving position of the received light to shift, and the received light cannot accurately enter the receiving channel. The transmission directions of the transmitted light and the received light are simplified, and the actual transmission directions of the transmitted light and the received light can change.

[0060] One solution to alleviate the walk-off effect of FMCW lidars is to increase the number of waveguides in each receiving channel, as Figure 3A and Figure 3B shown, to form a waveguide array to increase the equivalent receiving surface of the entire receiver, so that the lidar may still detect the optical signal after the received light generates a walk-off angle shift. Among them, Figure 3A takes the example of multiple receiving waveguides in one receiving channel corresponding to multiple detectors, Figure 3B takes the example of multiple receiving waveguides being combined into one waveguide and then corresponding to one detector. Of course Figure 3A 、 Figure 3B are just some examples of multi-waveguide schemes, and there can actually be other implementation methods of multi-waveguides.

[0061] However, the prerequisite for using this multi-waveguide receiving scheme is that the offset direction caused by the walk-off effect is parallel to the direction of the multi-waveguide arrangement. If the walk-off offset direction of the lidar is not parallel to the direction of the multi-waveguide arrangement, an additional optical transposition system is required to convert the walk-off offset direction into a direction parallel to the multi-waveguide arrangement direction. This increases the device complexity of the lidar, increases the optical adjustment time and cost, and reduces the reliability. Secondly, in the multi-waveguide receiving scheme, the number and cost of devices such as mixers, photodetectors (PDs), trans-impedance amplifiers (TIAs), and analog-to-digital converters (ADCs) will also increase several times, increasing the number, complexity, volume, and cost of the devices. In addition, even if the multi-waveguide receiving scheme is adopted, it can only improve the effect for multiple specific discrete walk-off offset angles, and the overall receiving efficiency of the lidar is still low. If N multi-waveguides are combined into a single waveguide and then received (as Figure 3B shown), the output optical power after beam combination is much smaller than the input optical power. For example, the output optical power after beam combination is 1 / N of the input optical power, and the overall optical receiving efficiency is poor.

[0062] To solve one or more of the above problems, the technical solutions of the embodiments of the present application are provided to improve (or solve) the problem of low receiving efficiency of the lidar caused by the walk-off effect, while taking into account reducing the hardware cost and product size.

[0063] See Figure 4 , which is a schematic structural diagram of a receiving component provided by an embodiment of the present application. The receiving component can be applied to a lidar. The receiving component includes a scanning device 01 and at least one receiving channel 02. The received light enters the receiving channel 02 after being reflected by the surface of the scanning device. It can be understood that Figure 4 only one receiving channel 02 is schematically shown in

[0064] and it is not limited to this in reality. Figure 4 As

[0065] It can be understood that the received light can reach the grating coupler 22 after passing through the receiving optical system. For example, the grating coupler 22 can specifically be used to couple the received light that has passed through the receiving optical system and is reflected back by the scanning device 01 into the receiving waveguide 21 corresponding to the grating coupler 22.

[0066] It can be understood that Figure 4 only one receiving waveguide 21 and one grating coupler 22 are schematically shown, and the actual situation is not limited to this.

[0067] It can be understood that the working principle of the grating coupler 22 is mainly based on the diffraction effect of the grating on light. When the incident light enters the grating coupler 22, due to the change in the refractive index of the grating of the grating coupler 22, a diffraction phenomenon will occur to form light interference. Through this interference, the grating coupler 22 can couple part of the incident light into the receiving waveguide 21.

[0068] In the embodiment of the present application, the receiving component of the lidar adopts a combination of a grating coupler 22 and a receiving waveguide 21. The grating coupler 22 couples the received light into the receiving waveguide 21. Compared with the end-face coupler, in the manufacturing process, the physical size of the receiving surface of the grating coupler 22 can be increased along the offset direction of the walk-off effect. Then, by further cooperating with the design of the grating layer structure of the grating coupler 22, the mode field of the grating coupler 22 can be increased at least in the offset direction of the walk-off effect, so that even if the received light is offset due to the walk-off effect, it can still be received by the grating coupler 22 and coupled into the receiving waveguide 21, thereby improving (or solving) the problem of low receiving efficiency of the lidar caused by the walk-off effect.

[0069] Moreover, in the embodiment of the present application, the number of waveguides can be reduced. For example, a receiving channel can have at least a combination of only one receiving waveguide 21 and one grating coupler 22, and there is no need to add an additional optical transposition system. Therefore, while improving the receiving efficiency of the lidar, the hardware cost and product size of the lidar can be reduced.

[0070] In addition, the position of the grating coupler 22 is relatively flexible and can be located at any position in the lidar chip. Therefore, unnecessary crossovers between waveguides can be minimized, and crosstalk between waveguides can be reduced, thereby improving the overall receiving performance of the lidar.

[0071] It can be understood that the received light described in this text being "received" by the grating coupler 22 means that the received light is "effectively received" by the grating coupler 22. For example, when the received light is "received and coupled into the receiving waveguide 21" by the grating coupler 22, it can ultimately be received by the lidar detector. In some embodiments, "receiving" in this text can also be described as "coupling", and "receiving efficiency" in this text can also be described as "coupling efficiency". For example, the receiving efficiency of the grating coupler 22 can also be referred to as the coupling efficiency of the grating coupler 22, which can be understood as the ratio of the light output (or received) by the grating coupler 22 to the light input into the grating coupler 22, and is used to describe the receiving effect (or coupling effect) of the grating coupler 22 on light.

[0072] It can be understood that the mode field of the grating coupler 22 described in this text refers to the part of the grating coupler 22 that can receive and transmit light. Only the received light incident on the mode field of the first grating layer 221 can be received by the first grating layer 221 and coupled into the receiving waveguide 21. In some embodiments, the mode field of the grating coupler 22 can also be referred to as the spatial mode field of the grating coupler 22, or the mode spot of the grating coupler 22, or the receiving surface or photosensitive surface of the grating coupler 22, etc.

[0073] In a possible design, as Figure 5 shown, the grating coupler 22 may include a first grating layer 221, and the first grating layer 221 includes a plurality of grating units 2211 arranged along a first direction. The plurality of grating units 2211 form the grating structure of the grating coupler 22. When light is incident on the first grating layer 221 along a third direction, the first grating layer 221 can couple the light into the receiving waveguide 21 along the thickness direction of the first grating layer 221.

[0074] The grating unit 2211 includes a part that can transmit light and a part that cannot transmit light. Figure 5 Taking the raised part as the part that can transmit light and the groove between two adjacent raised parts as the part that cannot transmit light as an example. As Figure 5 shown, the raised parts and the groove parts on the first grating layer 221 appear alternately and repeatedly. One raised part and a groove part adjacent to this raised part (on either side) constitute a grating period.

[0075] In some embodiments, each grating unit 2211 may include one raised part and a groove adjacent to it (on either side), that is, each grating unit 2211 may include one grating period (as Figure 5 shown); in other embodiments, each grating unit 2211 may include a plurality of raised parts and the groove parts adjacent to each of the plurality of raised parts, that is, each grating unit 2211 may include a plurality of grating periods ( Figure 5(not shown in the figure). For ease of description, in the following, one grating unit 2211 is taken as an example of one grating period for description.

[0076] The duty cycle of each grating unit 2211 among multiple grating units 2211 is within a first range. Herein, the duty cycle refers to the ratio of the light-transmitting part in the grating unit 2211 to the whole, such as the ratio of the protrusion in the grating unit 2211 to the grating unit 2211. When the duty cycle of the grating unit 2211 is within the first range, the grating unit 2211 can receive and transmit light, or in other words, the coupling efficiency of the grating unit 2211 exceeds a threshold (such as exceeding 0).

[0077] It can be understood that the grating units 2211 with the duty cycle within the first range constitute the mode field of the first grating layer 221, that is, the part of the first grating layer 221 that can receive and transmit light. Only the received light incident on the mode field of the first grating layer 221 can be received and transmitted by the first grating layer 221 (such as coupled to the receiving waveguide 21). It can be understood that the main part of the grating coupler 22 that couples light is the grating layer. Therefore, in some cases, the mode field of the first grating layer 221 can be equivalent to the mode field of the grating coupler 22.

[0078] In one possible example, the first range is a range where the duty cycle is greater than 0% and less than 100%, which can be expressed as (0%, 100%). Of course, this is only an example here, and it is not limited in reality. For example, the first range can also be (1%, 99%) or (5%, 95%) etc.

[0079] In some embodiments, there is a correlation between the duty cycle of the grating unit 2211 and the grating period of the grating unit 2211. When the duty cycle of the grating unit 2211 is within the first range, the grating period of the grating unit 2211 is within a second range.

[0080] For example, the correlation can be:

[0081] n eff -mλ / P = sinθ;

[0082] wherein, P is the grating period; neff is the effective refractive index of the grating, which is related to the duty cycle; λ is the light wavelength; θ is the angle between the emission / reception direction and the normal; m is the order.

[0083] Therefore, the description that the duty cycle of each grating unit 2211 among the above multiple grating units 2211 is within the first range can also be replaced with: the grating period of each grating unit 2211 among the multiple grating units 2211 is within the second range; or, the duty cycle of each grating unit 2211 among the multiple grating units 2211 is within the first range and the grating period of each grating unit 2211 among the multiple grating units 2211 is within the second range.

[0084] It can be understood that the duty cycle (or grating period) of the grating units 2211 at different positions in the first grating layer 221 can be the same or variable (i.e., different), and the embodiments of the present application do not make any restrictions. When the duty cycle of the grating units 2211 at different positions in the first grating layer 221 is variable, the variation can be regular or irregular. For example, Figure 5 in [description] it is taken as an example that the duty cycle of the grating unit 2211 increases along the thickness direction of the first grating layer 221, where the duty cycle of the grating unit 2211 closest to the receiving waveguide 21 is the largest, and the duty cycle of the grating unit 2211 farthest from the receiving waveguide 21 is the smallest. In practical applications, the design of the duty cycle (or grating period) of the grating units 2211 in the first grating layer 221 is not limited Figure 5 to the design method shown. For example, it can also be that the duty cycle of the grating unit 2211 closest to the receiving waveguide 21 is the smallest, and the duty cycle of the grating unit 2211 farthest from the receiving waveguide 21 is the largest.

[0085] The total length of the plurality of grating units 2211 in the first direction is greater than the first length. Wherein, the first direction corresponds to the offset direction of the walk-off effect generated by the scanning device 01, or the first direction corresponds to the scanning direction generated by the scanning device 01.

[0086] As an example, the first direction is the offset direction of the walk-off effect generated by the scanning device 01, the first direction is parallel to the offset direction of the walk-off effect generated by the scanning device 01, or the first direction is approximately parallel to the offset direction of the walk-off effect generated by the scanning device 01 (for example, the angle between the first direction and the offset direction is less than a preset value), etc. It can be understood that Figure 5 in [description] the offset direction is taken as an example of the direction from the receiving waveguide 21 to the grating unit 2211, but it is not limited thereto in practice. For example, it can also be the direction from the grating unit 2211 to the receiving waveguide 21 or other directions, etc.; Figure 5 it is taken as an example that the first direction is parallel to the offset direction of the walk-off effect generated by the scanning device 01, but it is not limited thereto in practice.

[0087] It can be understood that the walk-off effect is caused by the rotation of the scanning device 01. Therefore, the offset direction of the walk-off effect corresponds to the scanning direction of the scanning device 01. For example, the offset direction of the walk-off effect is parallel to the scanning direction of the scanning device 01. Of course, the corresponding relationship between the offset direction of the walk-off effect and the scanning direction of the scanning device 01 can also be other relationships. For example, when there is an optical transposition system that converts the walk-off offset direction into a direction perpendicular to the scanning direction of the scanning device 01, the offset direction of the walk-off effect is perpendicular to the scanning direction of the scanning device 01. For the sake of convenience of description, in this article, the example where the offset direction of the walk-off effect is parallel to the scanning direction of the scanning device 01 is taken.

[0088] Since the total length of the multiple grating units 2211 in the first direction is greater than the first length, and the duty cycle of each grating unit 2211 in the multiple grating units 2211 is within the first range, and the grating units 2211 with the duty cycle within the first range constitute the mode field of the first grating layer 221 (or the grating coupler 22), the length of the mode field of the first grating layer 221 (or the grating coupler 22) in the first direction is greater than the first length.

[0089] In some embodiments, the first length may be related to the maximum offset corresponding to the walk-off effect generated by the scanning device 01. Among them, the offset corresponding to the walk-off effect refers to the offset of the receiving position of the received light in the mode field of the first grating layer 221 (or the grating coupler 22). For example, the first length is a + b, where a represents the length of the spatial mode field of the received light (i.e., the spatial region where the received light is located, which can also be referred to as the mode field of the received light, or the optical mode spot, or the light spot, etc.) in the first direction, and b represents the maximum offset corresponding to the walk-off effect.

[0090] Through the above design, it can be realized that the length of the mode field of the grating coupler 22 in the offset direction of the walk-off effect generated by the scanning device 01 is greater than the first length. Furthermore, it can be ensured that the received light can still be located in the mode field of the grating coupler 22 after being offset due to the walk-off effect, thereby improving the receiving efficiency of the receiving component.

[0091] In a possible design, the total length of the multiple grating units 2211 in the first direction is greater than the first length, and the total length of the multiple grating units 2211 in the second direction is less than the first length. The second direction is different from the first direction. For example, the second direction is perpendicular to the first direction. Or, the length of the mode field of the grating coupler 22 in the second direction is less than the first length.

[0092] As an example, as Figure 6A shown, it is a top view of the first grating layer 221.Figure 6A It shows the shape of the mode field of the first grating layer 221 (or the grating coupler 22) when the total length of multiple grating units 2211 in the second direction is less than the first length. In this example, the shape of the mode field of the first grating layer 221 (or the grating coupler 22) is elliptical, where the major axis direction of the mode field is the first direction and the minor axis direction of the mode field is the second direction.

[0093] It can be understood that Figure 6A The shown elliptical mode field is only an example. In actual situations, the mode field of the first grating layer 221 (or the grating coupler 22) can also be rectangular, trapezoidal or other irregular shapes, and the embodiments of the present application do not make restrictions.

[0094] In this way, it can be achieved that the mode field of the first grating layer 221 (or the grating coupler 22) is increased in the offset direction of the walk-off effect, while it may not be increased in the second direction. Furthermore, while improving the reception efficiency of the first grating layer 221 (or the grating coupler 22), the size of the grating coupler 22 can be minimized as much as possible.

[0095] Optionally, the size of the mode field of the first grating layer 221 (or the grating coupler 22) in the second direction can match the spatial mode field of the received light in the second direction. In this way, the reception efficiency of the first grating layer 221 (or the grating coupler 22) can be further improved.

[0096] In another possible design, the total length of multiple grating units 2211 in the first direction is greater than the first length, and the total length of multiple grating units 2211 in the second direction is equal to (or approximately equal to) the total length of multiple grating units 2211 in the first direction, and the second direction is perpendicular to the first direction. Or, the length of the mode field of the grating coupler 22 in the second direction is equal to (or approximately equal to) the length of the mode field of the grating coupler 22 in the first direction.

[0097] As an example, as Figure 6B shown, it shows the shape of the mode field of the first grating layer 221 (or the grating coupler 22) when the total length of multiple grating units 2211 in the second direction is equal to the first length. In this example, the shape of the mode field is circular.

[0098] It can be understood that Figure 6B The shown circular mode field is only an example. In actual situations, the mode field of the first grating layer 221 (or the grating coupler 22) can also be square, rhombus or other shapes, and the embodiments of the present application do not make restrictions.

[0099] In this way, the mode field of the first grating layer 221 (or the grating coupler 22) can be increased in multiple directions (including the offset direction of the walk-off effect), further improving the reception efficiency of the first grating layer 221 (or the grating coupler 22).

[0100] In a possible design, the first grating unit 2211 among the multiple grating units 2211 is offset relative to the center of the multiple grating units 2211, and the offset direction of the first grating unit 2211 relative to the center is the same as the offset direction of the walk-off effect generated by the scanning device 01. In other words, the first grating unit 2211 is offset along a first direction relative to the center of the multiple grating units 2211.

[0101] The reception efficiency (or coupling efficiency) of the first grating unit 2211 is the maximum value among the reception efficiencies of each of the grating units 2211 in the multiple grating units 2211. For example, when the duty cycle of the first grating unit 2211 is a first value and / or the grating period of the first grating unit 2211 is a second value, the reception efficiency of the first grating unit 2211 is the maximum value among the reception efficiencies of each of the grating units 2211 in the multiple grating units 2211. Herein, the first value and / or the second value need to be determined according to the actual situation. For example, the first value may be 50% (i.e., the reception efficiency is the highest when the duty cycle is 50%), and the present application does not limit this.

[0102] In this way, the mode field of the first grating layer 221 (or the grating coupler 22) can be a mode field with a peak biased to one side, which can improve the reception efficiency of the first grating layer 221 (or the grating coupler 22) for the received light after offset. For example, Figure 6C As shown, it schematically shows the situation where the mode field of the first grating layer 221 (or the grating coupler 22) has a peak (reception efficiency) biased to one side, and the reception efficiency of the received light after offset is higher than that of the received light before offset (or without offset). It can be understood that Figure 6C taking an elliptical mode field as an example, in actual situations, the mode field of the first grating layer 221 (or the grating coupler 22) can also be rectangular, square, circular, rhombic or other shapes, and the embodiments of the present application do not limit this. Figure 6C Taking the area of the peak region being smaller than the optical mode spot area of the received light as an example, the actual situation is not limited to this.

[0103] Optionally, the offset of the first grating unit 2211 relative to the center is related to the maximum offset corresponding to the walk-off effect generated by the scanning device 01. For example, the offset of the first grating unit 2211 relative to the center is equal to the maximum offset corresponding to the walk-off effect generated by the scanning device 01. In this way, when the walk-off effect is the most severe (i.e., when the offset corresponding to the walk-off effect is the maximum), the position where the received light is located is exactly the peak position, and the first grating layer 221 (or the grating coupler 22) has the highest reception efficiency for the received light.

[0104] In a possible design, the first grating unit 2211 among the multiple grating units 2211 is located at the center of the multiple grating units 2211; wherein, the duty cycle of the first grating unit 2211 is a first value, and the grating period of the first grating unit 2211 is a second value. The reception efficiency (or coupling efficiency) of the first grating unit 2211 is the maximum among the reception efficiencies of each of the grating units 2211 in the multiple grating units 2211. For example, when the duty cycle of the first grating unit 2211 is the first value and / or the grating period of the first grating unit 2211 is the second value, the reception efficiency of the first grating unit 2211 is the maximum among the reception efficiencies of each of the grating units 2211 in the multiple grating units 2211.

[0105] In this way, the mode field of the first grating layer 221 (or the grating coupler 22) can be realized as a mode field with a peak at the center, and the reception efficiency of the received light before offset is higher. For example Figure 6D As shown, it schematically shows the case where the mode field of the first grating layer 221 (or the grating coupler 22) is a (reception efficiency) peak located at the center of the mode field. The received light before offset is exactly at the peak position and has the highest reception efficiency. It can be understood that Figure 6D taking an elliptical mode field as an example, in actual situations, the mode field of the first grating layer 221 (or the grating coupler 22) can also be rectangular, square, circular, rhombic or other shapes, which are not limited in the embodiments of the present application. Figure 6D Taking the area of the peak region as smaller than the optical mode spot area of the received light as an example, the actual situation is not limited to this.

[0106] In another possible design, the mode field of the first grating layer 221 (or the grating coupler 22) can also be designed as a Gaussian spot mode field or a quasi-Gaussian spot mode field, that is, the reception efficiency of the mode field decreases from the peak position in the mode field to the surroundings.

[0107] Exemplarily, in the first direction, it can be set that the receiving efficiency of the mode field decreases successively from the peak position in the mode field along the first direction and the reverse direction of the first direction. For example, the receiving efficiency (or coupling efficiency) of each grating unit 2211 among multiple grating units 2211 decreases successively along the direction from the first grating unit 2211 to the second grating unit 2211, and the second grating unit 2211 is the first grating unit 2211 and / or the last grating unit 2211 among multiple grating units 2211 in the first direction. For a specific implementation manner, for example, the duty cycle of each grating unit 2211 among multiple grating units 2211 can be set to increase or decrease successively along the direction from the first grating unit 2211 to the second grating unit 2211.

[0108] Exemplarily, in the second direction, it can be set that the receiving efficiency of the mode field decreases successively from the peak position in the mode field along the second direction and the reverse direction of the second direction. For example, the refractive index of each grating unit 2211 among multiple grating units 2211 can be set to decrease successively along the second direction and the reverse direction of the second direction. For a specific implementation manner, for example, materials or structures with different refractive indices are respectively adopted at different positions of the grating unit 2211 in the second direction.

[0109] As an example, as Figure 6E shown, it schematically shows a quasi-Gaussian spot mode field with the peak biased to one side. As another example, as Figure 6F shown, it schematically shows a quasi-Gaussian spot mode field with the peak located at the center. It can be understood that Figure 6E and Figure 6F take the elliptical mode field as an example. In actual situations, the mode field of the first grating layer 221 (or the grating coupler 22) can also be rectangular, square, circular, rhombic or other shapes, and the embodiments of the present application do not make any restrictions.

[0110] Through the above design, when the spot of the received light is a Gaussian spot or a quasi-Gaussian spot, the mode field distribution of the first grating layer 221 (or the grating coupler 22) matches the energy distribution of the spot of the received light, and the receiving efficiency of the first grating layer 221 (or the grating coupler 22) can be further improved.

[0111] It can be understood that in the Figures 6A to 6F given examples, the optical mode spots of the received light all take the circular shape as an example. In actual situations, it is not limited to this, and it can also be any other shape.

[0112] It can be understood that Figure 5 、 Figures 6A to 6F and other examples, the gratings of the grating coupler 22 (or the first grating layer 221) all take the straight grating as an example. For example, both the protrusions and the grooves take the straight strip shape (or rectangular shape) as an example. In actual situations, it is not limited to the straight grating, and it can also be a curved grating, such as Figure 6GAs shown, the protrusions and grooves are arc-shaped strips. In addition, the sizes of different grating units 2211 in the second direction may be the same or different, which is not limited in the embodiments of the present application.

[0113] In a possible design, the grating coupler 22 may be a multi-layer structure.

[0114] As an example, referring to Figure 7A , the grating coupler 22 further includes a reflective layer 222. The first grating layer 221 and the reflective layer 222 are stacked in sequence along the third direction, where the third direction is the incident direction of the received light on the grating coupler 22. The reflective layer 222 is used to reflect the light transmitted from the first grating layer 221 to the reflective layer 222 to improve the coupling efficiency of the first grating layer 221.

[0115] In a specific implementation, the reflective layer 222 may be a distributed Bragg reflector (DBR) layer, a metal layer, etc., which is not limited.

[0116] In this example, by providing the reflective layer 222 under the first grating layer 221, the receiving efficiency of the grating coupler 22 can be further improved.

[0117] As an example, referring to Figure 7B , the grating coupler 22 further includes a second grating layer 223. Figure 7B Taking the case where the second grating layer 223 is provided above the first grating layer 221 as an example, but it is not limited thereto in practice. The second grating layer 223 may also be provided below the first grating layer 221. The structure of the second grating layer 223 and the structure of the first grating layer 221 may be the same or different, which is not limited in the embodiments of the present application. In this case, the mode field of the grating coupler 22 is the union of the mode fields of the first grating layer 221 and the second grating layer 221.

[0118] It can be understood that Figure 7B taking two-layer gratings as an example, actually the grating coupler 22 may also be provided with more grating layers, which is not limited in the embodiments of the present application. In addition, Figure 7B to clearly illustrate the spatial position relationship between the first grating layer 221 and the second grating layer 223, the distance between the first grating layer 221 and the second grating layer 223 is exaggeratedly illustrated. In fact, the distance between the first grating layer 221 and the second grating layer 223 may be smaller, for example, they may be arranged closely.

[0119] In this example, by providing multiple layers of gratings, the receiving efficiency of the grating coupler 22 can be further improved.

[0120] As an example, the grating coupler 22 may further include a Buried Oxide (BOX) layer 224 and a substrate 225. As Figure 7C shown, a possible structure of the grating coupler 22 is schematically illustrated, including a first grating layer 221, a BOX layer, a reflective layer, and a substrate that are sequentially stacked in a third direction. Among them, the substrate 225 can serve to support other layers (such as the first grating layer 221, the BOX layer, and the reflective layer) in the grating coupler 22. The BOX layer 224 is used to separate the substrate layer 225 from other layers to prevent light from other layers from leaking into the substrate layer 225. In some embodiments, the substrate layer 225 may specifically be a silicon substrate.

[0121] It can be understood that Figures 7A to 7B these are only some examples of the layer structure of the grating coupler 22, and the actual layer structure of the grating coupler 22 is not limited thereto.

[0122] In a possible design, the scanning device 01 may be a one-dimensional (1D) scanning device, and the offset direction (or the first direction) of the walk-off effect generated by the scanning device 01 corresponds to the scanning direction of the scanning device 01. For example, Figure 8A and Figure 8B shown, where Figure 8A the scanning device 01 schematically illustrated takes a 1D galvanometer as an example, Figure 8B and the scanning device 01 shown takes a 1D rotating mirror as an example. It can be understood that Figure 8A in [the figure], the scanning device 01 is a 1D galvanometer, and its scanning method takes the back-and-forth swing as an example, so the scanning direction can have two directions. Correspondingly, the offset direction can correspond to any one of the two scanning directions, or simultaneously correspond to the two scanning directions; Figure 8B in [the figure], the scanning device 01 is a 1D rotating mirror, and its scanning method is a 360° rotational swing, so the scanning direction can have only one direction. Correspondingly, the offset direction also has only one. Of course, in practical applications, the scanning device 01 can also be other implementation methods such as MEMS galvanometers, Galvo scanning galvanometers, etc., without limitation.

[0123] In another possible design, the scanning device 01 is a two-dimensional (2D) scanning device, and the offset direction (or the first direction) of the walk-off effect generated by the scanning device 01 corresponds to the scanning direction of the fast axis in the two-dimensional scanning device 01. For example, Figure 8C and Figure 8D shown, where Figure 8C the scanning device 01 schematically illustrated takes a 2D galvanometer as an example, Figure 8D and the scanning device 01 shown takes a 1D rotating mirror + 1D galvanometer as an example. Of course, in practical applications, the 2D scanning device 01 can also be other implementation methods, without limitation.

[0124] Based on the same inventive concept, an embodiment of the present application further provides a lidar, which includes the receiving component described above, and further includes a transmitting component. The transmitting component and the receiving component share a scanning device 01.

[0125] In a possible design, as Figure 9 shown, the transmitting component may include a transmitting waveguide 31 and a grating coupler 32. The structural parameters of the grating layer in the grating coupler 32 in the transmitting component correspond to (for example, are the same as) the structural parameters of the grating layer in the grating coupler 22 in the receiving component. The structural parameters include, but are not limited to, one or more of structure, shape, size, grating period, duty cycle, etc. In this way, the receiving efficiency of the lidar is further improved.

[0126] Based on the same inventive concept, an embodiment of the present application further provides a terminal, which includes the receiving component or the lidar described above. The terminal includes, but is not limited to: smart home devices, such as televisions, floor sweeping robots, smart table lamps, audio systems, smart lighting systems, electrical control systems, home background music, home theater systems, intercom systems, video surveillance, etc.; intelligent transportation devices, such as cars, ships, drones, trains, trucks, etc.; intelligent manufacturing devices, such as robots, industrial equipment, intelligent logistics, intelligent factories, etc. Alternatively, the terminal device may also be a computer device with lidar detection capabilities, such as a desktop computer, a personal computer, a server, etc. It should also be understood that the terminal device may also be a portable electronic device with lidar detection capabilities, such as a mobile phone, a tablet computer, a palm computer, headphones, speakers, wearable devices (such as smart watches), vehicle-mounted devices, virtual reality devices, augmented reality devices, etc. Hereinafter, the lidar is taken as an example.

[0127] It can be understood that the plurality involved in the embodiments of the present application means two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after. In addition, it should be understood that although terms such as first and second may be used to describe various objects in the embodiments of the present invention, these objects should not be limited to these terms. These terms are only used to distinguish each object from each other.

[0128] In the description of the embodiments of the present application, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally further include other steps or units not listed, or may optionally further include other steps or units inherent to these processes, methods, products, or devices. It should be noted that in the embodiments of the present application, words such as "exemplary" or "for example" are used to represent examples, illustrations, or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0129] Those skilled in the art should understand that the embodiments of the present application may be provided as a method, system, or computer program product. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0130] The present application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the specified functions in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0131] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the specified functions in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0132] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions for implementing the process Figure 1 in one process or multiple processes and / or boxes Figure 1 steps for the functions specified in one box or multiple boxes.

Claims

1. A receiving component, characterized in that, Applied to a lidar, the receiving component includes a scanning device and at least one receiving channel; Each of the at least one receiving channels includes at least one receiving waveguide and at least one grating coupler, the receiving waveguides and the grating couplers are in one-to-one correspondence, and each of the at least one grating couplers is configured to couple the received light reflected back by the scanning device into the receiving waveguide corresponding to each grating coupler; Wherein, the grating coupler includes a first grating layer, the first grating layer includes a plurality of grating units arranged along a first direction, the duty cycle of each grating unit in the plurality of grating units is within a first range, the total length of the plurality of grating units in the first direction is greater than a first length, and the first direction corresponds to the scanning direction of the scanning device.

2. The receiving component according to claim 1, wherein The grating period of each grating unit in the plurality of grating units is within a second range.

3. The receiving component according to claim 1 or 2, characterized in that, The length of the mode field of the grating coupler in the first direction is greater than the first length.

4. The receiving component according to any one of claims 1-3, characterized in that, The first length is related to the maximum offset corresponding to the walk-off effect generated by the scanning device.

5. The receiving component according to any one of claims 1-4, characterized in that The scanning device is a two-dimensional scanning device, and the first direction corresponds to the scanning direction of the fast axis in the two-dimensional scanning device.

6. The receiving component according to any one of claims 1-5, characterized in that The total length of the plurality of grating units in a second direction perpendicular to the first direction is less than the first length.

7. The receiving component according to claim 6, wherein The length of the mode field of the grating coupler in the second direction is less than the first length.

8. The receiving component according to any one of claims 1-5, characterized in that, The total length of the plurality of grating units in a second direction perpendicular to the first direction is equal to the total length of the plurality of grating units in the first direction.

9. The receiving component according to claim 8, characterized in that, The length of the mode field of the grating coupler in the second direction is equal to the length of the mode field of the grating coupler in the first direction.

10. The receiving component according to any one of claims 1-9, characterized in that, The first grating unit among the plurality of grating units is offset relative to the center of the plurality of grating units, and the offset direction of the first grating unit relative to the center is the same as the offset direction of the walk-off effect generated by the scanning device; Wherein, the duty cycle of the first grating unit is a first value, and the grating period of the first grating unit is a second value.

11. The receiving component according to claim 10, wherein The offset amount of the first grating unit relative to the center is related to the maximum offset corresponding to the walk-off effect generated by the scanning device.

12. The receiving component according to any one of claims 1-9, characterized in that, The first grating unit among the plurality of grating units is located at the center of the plurality of grating units; wherein, the duty cycle of the first grating unit is a first value, and the grating period of the first grating unit is a second value.

13. The receiving component according to any one of claims 10-12, characterized in that, The coupling efficiency of the first grating unit is the maximum value among the coupling efficiencies of each grating unit in the plurality of grating units.

14. The receiving component according to any one of claims 10-13, characterized in that The duty cycle of each grating unit in the plurality of grating units gradually increases or decreases along the direction from the first grating unit to the second grating unit; or, the coupling efficiency of each grating unit in the plurality of grating units gradually decreases along the direction from the first grating unit to the second grating unit; Among them, the second grating unit is the first grating unit or the last grating unit of the plurality of grating units in the first direction.

15. The receiving component according to any one of claims 1-14, characterized in that, The grating coupler further includes a second grating layer disposed above or below the first grating layer.

16. The receiving component according to any one of claims 1-15, characterized in that, The grating coupler further includes a reflective layer disposed below the first grating layer, where the reflective layer is a distributed Bragg reflector (DBR) layer or a metal layer.

17. A lidar, characterized in that, The lidar includes the receiving component according to any one of claims 1-16. The lidar further includes a transmitting component, and the transmitting component and the receiving component share the scanning device.

18. The lidar according to claim 17, wherein The transmitting component includes a transmitting waveguide and a grating coupler. The structural parameters of the grating layer in the grating coupler of the transmitting component correspond to the structural parameters of the grating layer in the grating coupler of the receiving component, where the structural parameters include one or more of shape, size, grating period, and duty cycle.

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