Radar device having an improved signal-to-noise ratio

Abstract

To provide a LiDAR device with an improved S / N ratio.SOLUTION: LiDAR device is provided, comprising: a light source configured to generate light of a given wavelength; an optical transmitter configured to emit the light generated by the light source to the outside; an optical receiver configured to receive light from the outside; a resonance photodetector module configured to selectively amplify and detect light having the same wavelength as the wavelength of light generated by the light source from among the light received by the optical receiver; and a processor configured to control the light source and the resonance photodetector module.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rider device, and more particularly to a rider device having an improved signal-to-noise ratio.

Background Art

[0002] In recent years, ADAS (Advanced Driving Assistance System) with various functions has been commercialized. For example, ACC (Adaptive Cruise Control) that recognizes the position and speed of other vehicles, reduces the speed when there is a risk of collision, and drives the vehicle within a set speed range when there is no risk of collision, and AEB (Autonomous Emergency Braking System) that recognizes the vehicle ahead and automatically applies brakes to prevent a collision when there is a risk of collision but the driver does not respond or the response method is inappropriate. Vehicles equipped with such functions are increasing. In addition, it is expected that automobiles capable of autonomous driving will be commercialized in the near future.

[0003] As a result, the importance of vehicle radars that provide information about the front of the vehicle is gradually increasing. For example, a lidar (light detection and ranging) sensor that measures the distance, speed, azimuth angle position, etc. of a measurement target from the time it takes for a laser to be emitted and scattered or reflected and return, the change in laser intensity, the change in laser frequency, the change in polarization state of the laser, etc. is widely used as a vehicle radar.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

[0005] An object of the present invention is to provide a lidar device having an improved signal - noise ratio (SN ratio). [Means for Solving the Problems]

[0006] The lidar device according to the present embodiment can include a light source that generates light having a predetermined wavelength, an optical transmitter that emits the light generated from the light source to the outside, an optical receiver that receives light from the outside, a resonant optical detection module that selectively amplifies and detects light having the same wavelength as the light generated from the light source among the light received by the optical receiver, and a processor that controls the light source and the resonant optical detection module. Here, the resonant optical detection module can include a resonator, a phase modulator that is disposed on the resonator and adjusts the phase of the light traveling along the resonator based on the control of the processor, and a photodetector that detects the intensity of the light traveling along the resonator.

[0007] Before providing the light generated from the light source to the optical transmitter, the processor first provides it to the resonator, controls the phase modulator, and adjusts the phase of the light traveling along the resonator, so that the resonant wavelength of the resonator coincides with the wavelength of the light generated from the light source. After determining the resonant wavelength of the resonator, the light generated from the light source can be provided to the optical transmitter.

[0008] Also, while the processor controls the phase modulator and adjusts the phase of the light traveling along the resonator, when the intensity of the light detected by the photodetector reaches the maximum, it can be determined that the resonant wavelength of the resonator coincides with the wavelength of the light generated from the light source.

[0009] In one embodiment, the lidar device further includes a temperature sensor that measures the temperature of the light source, and the processor determines the wavelength of the light generated from the light source based on the temperature measured by the temperature sensor. If the wavelength of the light generated from the light source changes by a predetermined range or more, the phase modulator is controlled to adjust the phase of the light traveling along the resonator, so that the resonance wavelength of the resonator can be made to coincide with the wavelength of the light generated from the light source.

[0010] Further, the lidar device according to one embodiment may further include a first waveguide disposed between the light source and the optical transmitter, a second waveguide disposed between the light source and the resonator, a third waveguide disposed between the optical receiver and the resonator, and an optical switch that provides the light generated from the light source to the first waveguide or the second waveguide under the control of the processor.

[0011] Further, the lidar device according to one embodiment may further include an additional optical detector connected to the end of the third waveguide for measuring the intensity of external noise.

[0012] In another embodiment, the lidar device further includes an optical coupler disposed on the first waveguide, one end of the second waveguide extends to the optical coupler, and a part of the light provided to the optical transmitter via the first waveguide can be provided to the resonator via the optical coupler and the second waveguide.

[0013] For example, the light source is a continuous wave light source that generates continuous wave light, and the processor controls the light source so that the light source generates frequency-modulated light, and distance information and velocity information about an external object can be extracted by the FMCW (frequency modulated continuous wave) method.

[0014] In one embodiment, the resonator includes a first resonator and a second resonator having different optical path lengths and optically connected to each other. The phase modulator includes a first phase modulator disposed on the first resonator and configured to adjust the phase of light traveling along the first resonator based on the control of the processor, and a second phase modulator disposed on the second resonator and configured to adjust the phase of light traveling along the second resonator based on the control of the processor. The photodetector may include a first photodetector configured to detect the intensity of light traveling along the first resonator and a second photodetector configured to detect the intensity of light traveling along the second resonator.

[0015] In that case, before providing the light generated by the light source to the optical transmitter, the processor first provides the light to the first resonator, controls the first phase modulator, and adjusts the phase of the light traveling along the first resonator to match the resonance wavelength of the first resonator with the wavelength of the light generated by the light source. Then, the processor controls the second phase modulator and adjusts the phase of the light traveling along the second resonator to match the resonance wavelength of the second resonator with the wavelength of the light generated by the light source. After determining the resonance wavelengths of the first resonator and the second resonator, the processor can provide the light generated by the light source to the optical transmitter.

[0016] In another embodiment, the lidar device may further include a first waveguide disposed between the light source and the optical transmitter, a second waveguide disposed between the light source and the first resonator, a third waveguide disposed between the optical receiver and the second resonator, and an optical switch configured to provide the light generated by the light source to the first waveguide or the second waveguide under the control of the processor.

[0017] In yet another embodiment, the lidar device further includes a first waveguide disposed between the light source and the optical transmitter, an optical coupler disposed on the first waveguide, a second waveguide disposed between the optical coupler and the resonator, and a third waveguide disposed between the optical receiver and the resonator, and a part of the light provided to the optical transmitter via the first waveguide can be provided to the resonator via the optical coupler and the second waveguide.

[0018] In one embodiment, the resonator is, for example, a closed - curve waveguide resonator.

[0019] In other embodiments, the resonator includes a first loop - type mirror and a second loop - type mirror formed on a waveguide, and the phase modulator and the photodetector can be disposed on the waveguide between the first loop - type mirror and the second loop - type mirror.

[0020] In yet another embodiment, the lidar device further includes a first waveguide disposed between the light source and the optical transmitter, a second waveguide disposed between the light source and the first loop - type mirror, a third waveguide disposed between the optical receiver and the second loop - type mirror, and an optical switch that provides the light generated from the light source to the first waveguide or the second waveguide under the control of the processor.

[0021] The optical transmitter and the optical receiver are, for example, optical phased array (OPA) elements.

[0022] For example, the optical transmitter can include a substrate, a waveguide disposed on the substrate, a plurality of distributors each including an input end connected to one waveguide and an output end connected to a plurality of waveguides, a plurality of phase control elements that independently adjust the phases of the plurality of lights branched by the plurality of distributors, and a plurality of grating pattern groups each connected to the plurality of phase control elements and emitting the phase - adjusted plurality of lights.

[0023] The light source, the optical transmitter, the optical receiver, and the resonant optical detection module can be arranged together on one substrate.

[0024] The processor can adjust the azimuth angle direction of the light emitted from the optical transmitter by controlling the plurality of phase control elements and adjusting the phases of the branched plurality of lights, and can adjust the altitude angle direction of the light emitted from the optical transmitter by adjusting the wavelength of the light generated from the light source.

[0025] In addition, each time the processor changes the altitude angle direction of the light emitted from the optical transmitter, the processor can control the phase modulator to match the resonant wavelength of the resonator with the wavelength of the light generated from the light source.

[0026] For example, the processor controls the light source so that the light source generates light of a first wavelength, provides the first-wavelength light generated from the light source to the resonator, controls the phase modulator, and adjusts the phase of the light traveling along the resonator, so as to match the resonant wavelength of the resonator with the first wavelength. While providing the first-wavelength light generated from the light source to the optical transmitter, the processor controls the plurality of phase control elements to adjust the azimuth angle direction of the light emitted from the optical transmitter. The processor controls the light source so that the light source generates light of a second wavelength, provides the second-wavelength light generated from the light source to the resonator, controls the phase modulator, and adjusts the phase of the light traveling along the resonator, so as to match the resonant wavelength of the resonator with the second wavelength. While providing the second-wavelength light generated from the light source to the optical transmitter, the processor controls the plurality of phase control elements to adjust the azimuth angle direction of the light emitted from the optical transmitter.

[0027] Also, in another embodiment, the optical transmitter and the optical receiver are, for example, an integrated optical transceiver.

[0028] In that case, the lidar device includes a first waveguide disposed between the light source and the optical transceiver, a second waveguide disposed between the light source and the resonator, a third waveguide disposed between the optical transceiver and the resonator, and an optical switch that provides the light generated from the light source to the first waveguide or the second waveguide under the control of the processor, and an optical coupler disposed on the first waveguide, one end of the third waveguide is connected to the optical coupler, and the optical coupler can transmit the light received by the optical transceiver to the third waveguide.

[0029] In another embodiment, the lidar device includes an optical circulator that outputs the light input to the first port to the second port and outputs the light input to the second port to the third port, a first waveguide connected between the light source and the first port of the optical circulator, an optical coupler disposed on the first waveguide, a second waveguide connected between the resonator and the optical coupler, and a third waveguide connected between the third port of the optical circulator and the resonator, and the optical transceiver can be connected to the third port of the optical circulator.

Brief Description of the Drawings

[0030]

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Best Mode for Carrying Out the Invention

[0031] Hereinafter, with reference to the accompanying drawings, a lidar device having an improved signal - noise ratio will be described in detail. In the following drawings, the same reference numerals refer to the same components, and on the drawings, the size of each component may be exaggerated for clarity and convenience of explanation. On the other hand, the embodiments described below are merely exemplary, and various modifications are possible from those embodiments.

[0032] Hereinafter, those described as "upper" or "above" include not only those in direct contact and directly above but also those non - contact and above. Singular expressions include plural expressions unless clearly specified otherwise in the context. Also, when a part "includes" a certain component, it means that, unless otherwise stated to the contrary, it does not exclude other components but further includes other components.

[0033] The use of the term "the foregoing" and similar directive terms applies to both singular and plural. For the steps constituting a method, if the order is not clearly described or there is no contrary description, the steps may be performed in an appropriate order and are not necessarily limited to the described order.

[0034] Also, terms such as "… part" and "module" described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software, or by a combination of hardware and software.

[0035] The connection of lines or connection members between the components shown in the drawings illustratively represents a functional connection and / or a physical or circuit connection. In an actual device, it is represented as various functional connections, physical connections, or circuit connections that may be alternative or additional.

[0036] The use of all examples or exemplary terms is merely for the purpose of explaining the technical idea in detail and is not intended to limit the scope by such examples or exemplary terms, unless otherwise limited by the claims.

[0037] FIG. 1 is a block diagram schematically showing the configuration of a rider device according to an embodiment. Referring to FIG. 1, a rider device 100 according to an embodiment includes a light source 110 that generates light having a predetermined wavelength, an optical transmitter 120 that emits the light generated from the light source 110 to the outside, an optical receiver 130 that receives light from the outside, and a resonant optical detection module 140 that selectively amplifies and detects light having the same wavelength as the light generated from the light source 110 among the light received by the optical receiver 130, and a processor 150 that controls the operations of the light source 110 and the resonant optical detection module 140.

[0038] The light source 110 is configured to emit pulsed light at regular time intervals under the control of the processor 150. Also, the light source 110 may be configured to emit light in an infrared band that is invisible to the naked eye. For example, the light source 110 may be configured to emit light having a selected partial wavelength band within the range of about 800 nm to about 2,000 nm. The light source 110 is, for example, a pulsed laser light source, but is not necessarily limited thereto. If the emission wavelength can be controlled within a tolerance range, a light-emitting diode (LED) can also be used as the light source 110.

[0039] The optical transmitter 120 is configured to direct and transmit the light generated from the light source 110 in a specific direction under the control of the processor 150. The optical transmitter 120 is also a beam steering device that sequentially irradiates light on a plurality of regions in the front. Hereinafter, the light emitted from the optical transmitter 120 to the outside is referred to as signal light. For example, the optical transmitter 120 irradiates the signal light while sequentially changing the azimuth angle at a selected elevation angle, then changes the elevation angle, and irradiates the signal light again while sequentially changing the azimuth angle, and can perform two-dimensional scanning with respect to the front.

[0040] The optical transmitter 120 can be implemented, for example, by an optical phased array (OPA) method, but is not necessarily limited thereto. For example, the optical transmitter 120 can also include an actuator that rotates the light source 110. In that case, the optical transmitter 120 can adjust the irradiation direction of the signal light by rotating the light source 110. In another example, the optical transmitter 120 can include a mirror that reflects the light generated from the light source 110 and an actuator that rotates the mirror, or can include a micro electro mechanical system (MEMS) element that electro-mechanically adjusts the reflection direction of the light generated from the light source 110.

[0041] The optical receiver 130 serves to receive the light reflected from the forward object OBJ. The optical receiver 130 can receive all the light coming from the outside toward the lidar device 100, but in particular, it may be configured to receive the light coming from the direction in which the optical transmitter 120 transmits the signal light. For example, the optical receiver 130 can also be implemented by an optical phased array method. Alternatively, the optical receiver 130 can be implemented as a lens array in which a plurality of microlenses are two-dimensionally arranged. When the optical receiver 130 is implemented as a lens array, the optical receiver 130 may further include an actuator that adjusts the direction of the lens array under the control of the processor 150.

[0042] In addition, the lidar device 100 may further include an optical system 160 configured to project the signal light emitted from the optical transmitter 120 to the outside as needed. The optical system 160 can focus the beam diameter of the signal light emitted from the optical transmitter 120 so that it does not increase to a long distance. The optical system 160 can also focus the light coming from the outside onto the optical receiver 130. However, when the signal light with a sufficiently controlled beam diameter is emitted from the optical transmitter 120, the optical system 160 may be omitted.

[0043] In addition, the rider device 100 may further include a band - pass filter 161 that selectively transmits only light in a specific wavelength band among the light coming from the outside toward the rider device 100. The band - pass filter 161 is disposed opposite to the light - receiving surface of the photoreceiver 130 and can limit the wavelength band of the light incident on the photoreceiver 130. The pass - band of the band - pass filter 161 also coincides with the wavelength band of the signal light. For example, when the light source 110 emits light having a wavelength band selected from the band of about 800 nm to about 2,000 nm, the pass - band of the band - pass filter 161 can be selected within the range of about 800 nm to about 2,000 nm.

[0044] The processor 150 controls the operations of the light source 110, the optical transmitter 120, and the photoreceiver 130, and based on the received signal received from the resonant optical detection module 140, for example, by the time - of - flight (TOF) method, distance information or velocity information about an external object OBJ can be extracted. The processor 150 can be implemented, for example, by a dedicated semiconductor chip, or by software executable by a computer and stored in a recording medium. According to still other examples, the processor 150 can also be implemented by a programmable logic controller (PLC) or a field - programmable gate array (FPGA), etc. Also, the processor 150 may be mounted on one substrate together with the light source 110, the optical transmitter 120, the photoreceiver 130, and the resonant optical detection module 140, or may be mounted on separate substrates from each other.

[0045] The resonance-type optical detection module 140 serves to improve the signal-to-noise ratio of the lidar device 100 by selectively amplifying and detecting light having the same wavelength as the signal light among the light received by the optical receiver 130. Even when using the band-pass filter 161, when considering the wavelength change of the light source 110, the pass bandwidth of the band-pass filter 161 is selected to be about several tens of nm. Therefore, even when using the band-pass filter 161, external noise such as sunlight, streetlights, and the headlights of other vehicles can flow into the resonance-type optical detection module 140 via the optical receiver 130. The resonance-type optical detection module 140 can selectively detect only the light having the same wavelength as the signal light among the light received by the optical receiver 130.

[0046] Therefore, the resonance-type optical detection module 140 includes a resonator 141, a phase modulator 142 disposed on the resonator 141 and configured to adjust the phase of the light traveling along the resonator 141 based on the control of the processor 150, and a photodetector 143 configured to detect the intensity of the light traveling along the resonator 141.

[0047] The resonator 141 is also, for example, a closed-loop waveguide resonator. In FIG. 1, for the sake of convenience, the resonator 141 is shown as being circular, but the form of the resonator 141 does not necessarily have to be circular, and may have any form such as an ellipse or a polygon as long as it has a closed-loop structure. The resonance wavelength of the resonator 141 is also determined by the optical length of the closed-loop waveguide. The optical length of the closed-loop waveguide can be represented by the product of the physical length of the closed-loop waveguide and the average refractive index of the closed-loop waveguide.

[0048] The wavelength of the light generated from the light source 110 changes based on the control of the processor 150 as needed and also changes due to external environmental variables such as temperature. The phase modulator 142 functions to match the resonance wavelength of the resonator 141 with the wavelength of the light generated from the light source 110 based on the control of the processor 150. For example, if the phase of the light traveling along the resonator 141 changes, an effect occurs where the optical length of the closed-loop waveguide changes, and the resonance wavelength of the resonator 141 changes. If the optical phase delay of the light increases, the optical length of the closed-loop waveguide becomes longer, so the resonance wavelength of the resonator 141 increases. Conversely, if the optical phase delay of the light decreases, the optical length of the closed-loop waveguide becomes shorter, so the resonance wavelength of the resonator 141 decreases. Therefore, the phase modulator 142 is disposed on the resonator 141, and by adjusting the phase of the light traveling along the resonator 141, the resonance wavelength of the resonator 141 can be adjusted.

[0049] The phase modulator 142 can also be implemented by changing the temperature of the waveguide or by changing the concentration of carriers (e.g., electrons or holes). For example, the temperature change method can adjust the phase of the light by changing the temperature around the waveguide and changing the refractive index of the waveguide. Also, the carrier concentration change method can adjust the phase of the light by positioning a diode junction around the center of the waveguide and changing the refractive index of the waveguide through a change in the carrier concentration.

[0050] The photodetector 143 detects the intensity of the light traveling along the resonator 141. If the photodetector 143 absorbs all the light traveling along the resonator 141, resonance does not occur in the resonator 141. Therefore, the photodetector 143 can absorb and detect only a part of the light traveling along the resonator 141 and allow the remaining light to pass through and continue to travel along the resonator 141. The intensity of the light detected by the photodetector 143 is the intensity of the light corresponding to the resonance wavelength of the resonator 141. Therefore, the photodetector 143 measures the intensity of the light having the same wavelength as the wavelength of the light generated from the light source 110.

[0051] Further, the lidar device 100 may further include an optical switch 101 that, under the control of the processor 150, provides the light generated from the light source 110 to the first waveguide 102 or the second waveguide 103, where the first waveguide 102 is disposed between the light source 110 and the optical transmitter 120, the second waveguide 103 is disposed between the light source 110 and the resonator 141, and the third waveguide 104 is disposed between the optical receiver 130 and the resonator 141.

[0052] The optical switch 101, the first waveguide 102, the second waveguide 103, and the third waveguide 104 are mounted on the same substrate together with the resonant optical detection module 140, the optical transmitter 120, and the optical receiver 130, but are not necessarily limited thereto. For example, the first waveguide 102, the second waveguide 103, and the third waveguide 104 may each be made of an optical fiber, and the optical switch 101, the resonant optical detection module 140, the optical transmitter 120, and the optical receiver 130 may be individually fixed inside the case of the lidar device 100.

[0053] The optical switch 101 is an element whose optical path changes by an electrical signal. For example, the optical switch 101 can be implemented in various ways such as a Mach-Zehnder interferometer switch, a heating heater, or a combination thereof.

[0054] The first end of the first waveguide 102 is connected to the optical switch 101, and the second end on the opposite side of the first end is connected to the input port of the optical transmitter 120. When the optical switch 101 provides the light generated from the light source 110 to the first waveguide 102 under the control of the processor 150, the light generated from the light source 110 is supplied to the optical transmitter 120 along the first waveguide 102.

[0055] Further, the first end of the second waveguide 103 is connected to the optical switch 101, and a partial region of the second waveguide 103 including the second end on the opposite side of the first end is disposed adjacent to the resonator 141. A partial region of the second waveguide 103 is disposed in a direction parallel to the tangential direction of the resonator 141 but does not physically contact the resonator 141. For example, the shortest distance between the resonator 141 and the second waveguide 103 is greater than 0 and not more than 5 times the width of the second waveguide 103. Also, the shortest distance between the resonator 141 and the second waveguide 103 is not more than 2 times the width of the second waveguide 103, for example, from half the width of the second waveguide 103 to the same width as the width of the second waveguide 103. Thereby, without the second waveguide 103 affecting the resonance wavelength of the resonator 141, the light traveling along the second waveguide 103 toward the second end is transmitted to the resonator 141. When the optical switch 101 provides the light generated from the light source 110 to the second waveguide 103 under the control of the processor 150, the light generated from the light source 110 is supplied to the resonator 141 along the second waveguide 103.

[0056] The first end of the third waveguide 104 is connected to the optical receiver 130, and a partial region of the third waveguide 104 including the second end on the opposite side of the first end is disposed adjacent to the resonator 141. A partial region of the third waveguide 104 is disposed in a direction parallel to the tangential direction of the resonator 141 but does not physically contact the resonator 141. For example, the shortest distance between the resonator 141 and the third waveguide 104 is greater than 0 and not more than 5 times the width of the third waveguide 104. Also, the shortest distance between the resonator 141 and the third waveguide 104 is not more than 2 times the width of the third waveguide 104, for example, from half the width of the third waveguide 104 to the same width as the width of the third waveguide 104. Thereby, without the third waveguide 104 affecting the resonance wavelength of the resonator 141, the light incident on the first end of the third waveguide 104 from the optical receiver 130 is transmitted to the resonator 141 in the process of traveling along the third waveguide 104 toward the second end. The third waveguide 104 is disposed on the opposite side of the second waveguide 103 with the resonator 141 as the center, but is not necessarily limited thereto.

[0057] In the lidar device 100 having the above structure, before providing the light generated from the light source 110 to the optical transmitter 120 and emitting the light to the outside through the optical transmitter 120, the resonator 141 is first provided with the light, and the resonance wavelength of the resonator 141 is made to coincide with the wavelength of the light generated from the light source 110. Then, the optical transmitter 120 is supplied with the light and emits the light to the outside, and among the light received from the optical receiver 130, only the signal light corresponding to the resonance wavelength of the resonator 141 can be selectively amplified and detected. For example, FIGS. 2A and 2B are block diagrams for schematically explaining the operation of the lidar device 100 shown in FIG. 1.

[0058] First, FIG. 2A shows the process of tuning the resonance wavelength of the resonator 141 so as to coincide with the wavelength of the light generated from the light source 110. Referring to FIG. 2A, the processor 150 controls the optical switch 101 to optically connect the light source 110 and the second waveguide 103. Then, the processor 150 turns on the light source 110 to generate light. At that time, the processor 150 can also control the light source 110 to adjust the wavelength of the light generated from the light source 110. The light generated from the light source 110 is transmitted to the resonator 141 through the second waveguide 103 and resonates within the resonator 141. The processor 150 controls the phase modulator 142 while monitoring the output of the photodetector 143, and gradually changes the phase of the light traveling along the resonator 141. The process of adjusting the phase delay by the phase modulator 142 is repeated until the output of the photodetector 143 becomes maximum.

[0059] The processor 150 controls the phase modulator 142 and, while adjusting the phase of the light traveling along the resonator 141, determines that the resonance wavelength of the resonator 141 coincides with the wavelength of the light generated from the light source 110 when the intensity of the light detected by the photodetector 143 reaches its maximum. After determining the resonance wavelength of the resonator 141 in such a manner, the processor 150 can end the tuning mode shown in FIG. 2A and fixedly maintain the wavelength of the light source 110 determined in the tuning mode and the phase delay by the phase modulator 142. If necessary, the processor 150 may store the control conditions determined in the tuning mode in the memory.

[0060] Thereafter, the processor 150 performs the signal detection mode. For example, as shown in FIG. 2B, the processor 150 controls the optical switch 101 to optically connect the light source 110 and the first waveguide 102. Thereby, the light generated from the light source 110 is transmitted to the optical transmitter 120 through the first waveguide 102. The processor 150 can control the optical transmitter 120 to irradiate light sequentially or irregularly to a plurality of regions ahead. In the signal detection mode, the processor 150 can maintain the wavelength of the light source 110 determined in the tuning mode and the phase delay by the phase modulator 142.

[0061] On the other hand, the light incident on the optical receiver 130 from the outside will travel along the third waveguide 104. Among the light traveling along the third waveguide 104, only the light having a wavelength that satisfies the resonance condition of the resonator 141 resonates within the resonator 141 and is detected by the photodetector 143. The light having a wavelength that satisfies the resonance condition of the resonator 141 includes not only the light having a wavelength that exactly coincides with the wavelength of the signal light but also the light having a plurality of wavelengths corresponding to an integral multiple of the optical length of the closed-loop waveguide of the resonator 141.

[0062] For example, FIG. 3 is a graph exemplarily showing the distribution of signals detected by the rider device 100 shown in FIG. 1. Referring to FIG. 3, external noise entering together with the signal light via the optical receiver 130 is distributed over a wide wavelength band of at least several tens of nm or more. Most of such external noise is a component that does not exactly match the resonance wavelength of the resonator 141. Therefore, the signal light component entering the resonator 141 is amplified by the closed-loop waveguide, and the noise component exits through the second end of the third waveguide 104 and is scattered and disappears in the circuit board on which the third waveguide 104 is mounted or in the chip including the third waveguide 104.

[0063] Only the component of the external noise that matches the resonance wavelength of the resonator 141 is detected by the photodetector 143 together with the signal light. For example, FIG. 3 exemplarily shows a plurality of peaks corresponding to the resonance wavelength of the resonator 141. As exemplarily shown in the graph of FIG. 3, noise with a width of about 0.01 nm based on the half-value width is detected by the photodetector 143 every period of about 1 nm. Therefore, when assuming that the external noise entering together with the signal light via the optical receiver 130 includes light with a uniform intensity over the entire wavelength band, only about 1 / 100 of the external noise is detected by the photodetector 143, and the signal-to-noise ratio of the rider device 100 is improved by the noise reduced in this way. The period and width of the peaks shown in FIG. 3 can be determined by various design elements such as the length, loss, and distance from the third waveguide 104 of the closed-loop waveguide of the resonator 141. Therefore, the numerical values exemplified above are merely examples for understanding.

[0064] The intensity of the light incident on the photodetector 143 optically coupled to the resonator 141 has an effect of being amplified by several tens of times more than the actual due to the resonance phenomenon in the resonator 141. Therefore, it can have the same effect as if the sensitivity of the photodetector 143 is increased. Due to such an effect, the signal-to-noise ratio of the rider device 100 is improved. Therefore, even if the band-pass filter 161 shown in FIG. 1 is removed, a high signal-to-noise ratio can be achieved.

[0065] As described above, the photodetector 143 can absorb and detect only a part of the light traveling along the resonator 141, without absorbing all of it. Such conditions enable the use of a silicon photodetector. An ideal silicon crystal absorbs visible light but does not absorb light in the infrared wavelength region. However, in reality, infrared absorption due to two-photon absorption caused by lattice defects existing inside and on the surface of silicon is observed. The generation of photocurrent by the two-photon absorption mechanism is generally known to be very weak, at about 5 mA / W level. However, in the case of the lidar device 100 according to the present embodiment, by coupling a silicon photodetector to the resonator 141, a responsivity of about 0.1 A / W level can be obtained. It is similar to the responsivity of photodetectors using germanium (Ge) or III-V compound semiconductors for the infrared wavelength region.

[0066] Therefore, it is possible to use a silicon detector as the photodetector 143 for detecting signals in the infrared wavelength region. By using a silicon detector, as long as the resonance phenomenon in the resonator 141 can be maintained, only a part of the light can be absorbed. Also, by being coupled to the resonator 141, the silicon detector can achieve performance similar to that of infrared detectors using other semiconductor materials. If a silicon detector is used as the photodetector 143, the optical transmitter 120, the optical receiver 130, and the resonant photodetection module 140 shown in FIG. 1 can be realized by directly using the current CMOS (complementary metal oxide semiconductor) manufacturing process, so that the production cost of the lidar device 100 can be greatly reduced.

[0067] FIG. 1 shows the photodetector 143 disposed on the closed-loop waveguide of the resonator 141, but is not necessarily limited thereto. For example, FIG. 4 illustratively shows another configuration of the resonant photodetection module of the lidar device 100 shown in FIG. 1. Referring to FIG. 4, the resonant photodetection module 140a includes an optical coupler 144 disposed on the closed-loop waveguide of the resonator 141 and a photodetector 143 coupled to the optical coupler 144. The optical coupler 144 provides a portion of the light traveling in the resonator 141 to the photodetector 143.

[0068] FIG. 5 is a block diagram schematically showing the configuration of a lidar device according to another embodiment. Referring to FIG. 5, the lidar device 100a may further include a temperature sensor 151. The temperature sensor 151 is arranged to measure the temperature around the lidar device 100a, particularly the temperature of the light source 110. The wavelength of the light generated from the light source 110 is generally greatly affected by temperature. The processor 150 may include a memory storing the relationship between the temperature of the light source 110 and the wavelength of the light.

[0069] While performing the tuning mode shown in FIG. 2A, the processor 150 can store the temperature measured by the temperature sensor 151 in the memory. Then, while performing the signal detection mode shown in FIG. 2B, the processor 150 can monitor the temperature of the light source 110 from the temperature sensor 151. During the signal detection mode, if the temperature measured by the temperature sensor 151 is significantly different from the temperature stored in the memory, the processor 150 temporarily interrupts the signal detection mode and performs the tuning mode again. For example, compared with the wavelength of the light generated from the light source 110 calculated based on the temperature measured during the tuning mode, if the wavelength of the light generated from the light source 110 calculated based on the temperature measured during the signal detection mode changes so that it does not sufficiently satisfy the resonance condition of the resonator 141, the processor 150 interrupts the signal detection mode and performs the tuning mode. For example, if the wavelength of the light generated from the light source 110 changes by about 1 nm or more, the processor 150 performs the tuning mode again. In such a manner, the processor 150 can match the resonance wavelength of the resonator 141 to the changed wavelength of the light generated from the light source 110 in real time.

[0070] FIG. 6 is a block diagram schematically showing the configuration of a lidar device according to still another embodiment. Referring to FIG. 6, the lidar device 100b may further include an additional photodetector 152 disposed at the second end of the third waveguide 104. As described above, among the light entering through the optical receiver 130, the signal light component is amplified by the resonator 141, and the noise component travels toward the second end of the third waveguide 104. Therefore, the photodetector 152 disposed at the second end of the third waveguide 104 can measure the intensity of the external noise. The wavelength distribution of the external noise can vary depending on the external conditions, for example, day, night, tunnel, weather, etc. The processor 150 can predict the external conditions based on the wavelength distribution of the external noise provided from the photodetector 152 and provide external information to the user.

[0071] FIG. 7 is a block diagram schematically showing the configuration of a rider device according to still another embodiment. Referring to FIG. 7, the rider device 100c may include a resonant optical detection module 140b including at least two resonators having different optical path lengths and optically connected to each other. For example, the resonant optical detection module 140b includes a first resonator 141a having a first optical path length, a first phase modulator 142a disposed on the first resonator 141a and configured to adjust the phase of light traveling along the first resonator 141a, a first photodetector 143a configured to detect the intensity of light traveling along the first resonator 141a, a second resonator 141b having a second optical path length different from the first optical path length, a second phase modulator 142b disposed on the second resonator 141b and configured to adjust the phase of light traveling along the second resonator 141b, and a second photodetector 143b configured to detect the intensity of light traveling along the second resonator 141b.

[0072] The first resonator 141a and the second resonator 141b are, for example, also closed-loop waveguide resonators. In FIG. 7, illustratively, the first resonator 141a is shown as a circular closed-loop waveguide having a first diameter R1, and the second resonator 141b is shown as a circular closed-loop waveguide having a second diameter R2 different from the first diameter R1. However, the closed-loop waveguides of the first resonator 141a and the second resonator 141b do not necessarily have to be circular, and closed-loop waveguides having various forms with different optical path lengths may be used. Also, it is possible that the closed-loop waveguide of the first resonator 141a and the closed-loop waveguide of the second resonator 141b have different forms.

[0073] The second waveguide 103 optically connected to the optical switch 101 is arranged to transmit the light generated from the light source 110 to the first resonator 141a. The third waveguide 104 optically connected to the optical receiver 130 is arranged to transmit the light entering the optical receiver 130 to the second resonator 141b. For example, the second waveguide 103 is arranged in a direction parallel to the tangent direction of the first resonator 141a in the vicinity of the first resonator 141a, and the third waveguide 104 is arranged in a direction parallel to the tangent direction of the second resonator 141b in the vicinity of the second resonator 141b.

[0074] The first resonator 141a and the second resonator 141b are optically connected to each other. For example, the resonant optical detection module 140b may further include a fourth waveguide 145 connected between the first resonator 141a and the second resonator 141b. Light traveling along the first resonator 141a is transmitted to the second resonator 141b via the fourth waveguide 145, and light traveling along the second resonator 141b is transmitted to the first resonator 141a via the fourth waveguide 145. Therefore, the light supplied to the first resonator 141a via the second waveguide 103 and the light supplied to the second resonator 141b via the third waveguide 104 will travel in an "8" shape along the first resonator 141a and the second resonator 141b.

[0075] If the optical path length of the closed-loop waveguide changes, the resonant wavelength of the resonator changes, and the interval between the resonant wavelengths, that is, the resonant period also changes. When two closed-loop waveguides are connected in series, a signal is detected when the resonance conditions of both closed-loop waveguides are satisfied. Therefore, the external noise detected together with the signal is also limited to the wavelength at which the resonance conditions of the two closed-loop waveguides are simultaneously satisfied, and as a result, the effect of increasing the resonant period is obtained.

[0076] For example, FIG. 8 exemplarily shows the resonance characteristics of the first and second resonators 141a and 141b, respectively, and the resulting resonance characteristics of the resonant optical detection module 140b in the lidar device 100c shown in FIG. 7. The resonant period of the resonator is proportional to the reciprocal of the optical path length, and as the optical path length increases, the resonant period becomes shorter. In FIG. 8, it is assumed that the first resonator 141a and the second resonator 141b are circular closed-loop waveguides having diameters R1 and R2, respectively. Referring to FIG. 8, the resonant periods of the first and second resonators 141a and 141b are relatively short, but the resulting resonant period of the resonant optical detection module 140b due to the series connection of the first resonator 141a and the second resonator 141b becomes very long. For example, the resonant period of the resulting resonant optical detection module 140b is the same as the least common multiple of the resonant period of the first resonator 141a and the resonant period of the second resonator 141b. Therefore, the external noise detected by the first photodetector 143a and the second photodetector 143b can be further reduced.

[0077] When using two resonators, the tuning mode is performed sequentially for each resonator. For example, the processor 150 first controls the phase delay by the first phase modulator 142a until the intensity of the light measured by the first photodetector 143a reaches the maximum. In such a manner, the resonant wavelength of the first resonator 141a is made to coincide with the wavelength of the light generated from the light source 110. When the intensity of the light measured by the first photodetector 143a reaches the maximum, the processor 150 then controls the phase delay by the second phase modulator 142b until the intensity of the light measured by the second photodetector 143b reaches the maximum. In such a manner, the resonant wavelength of the second resonator 141b is made to coincide with the wavelength of the light generated from the light source 110.

[0078] After the processor 150 determines the resonant wavelengths of the first resonator 141a and the second resonator 141b, the processor 150 provides the light generated from the light source 110 to the optical transmitter 120 and performs the signal detection mode. In the signal detection mode, the processor 150 can calculate information about an external object by using both the signal detected by the first photodetector 143a and the signal detected by the second photodetector 143b. By using two photodetectors, the accuracy and precision in the tuning mode and the signal detection mode can be improved.

[0079] FIG. 7 shows the first resonator 141a and the second resonator 141b connected in series via the fourth waveguide 145, but is not necessarily limited thereto. For example, FIG. 9 illustratively shows another configuration of the resonant optical detection module of the lidar device 100c shown in FIG. 7. Referring to FIG. 9, the resonant optical detection module 140c includes a first resonator 141a and a second resonator 141b that are close to each other without the fourth waveguide 145. The first resonator 141a and the second resonator 141b do not physically contact each other, and the shortest distance between the first resonator 141a and the second resonator 141b is, for example, greater than 0 and less than or equal to 5 times the width of the closed curve waveguide. Also, the shortest distance between the first resonator 141a and the second resonator 141b is less than or equal to 2 times the width of the closed curve waveguide, for example, from half the width of the closed curve waveguide to the same width as the width. The remaining configuration of the resonant optical detection module 140c is the same as the configuration of the resonant optical detection module 140b shown in FIG. 7.

[0080] FIG. 10 is a block diagram schematically showing the configuration of a lidar device according to still another embodiment. Referring to FIG. 10, the lidar device 100d may further include an optical coupler 105 disposed on the first waveguide 102. Accordingly, the optical coupler 105 is disposed in the optical path between the optical switch 101 and the optical transmitter 120. Also, the first end of the second waveguide 103 of the lidar device 100d is connected to the optical switch 101, and the second end is extended to the optical coupler 105. A part of the region between the first end and the second end of the second waveguide 103 is adjacent to the resonator 141 and passes in the tangential direction of the resonator 141.

[0081] According to this embodiment, a part of the light generated from the light source 110 and provided to the optical transmitter 120 via the first waveguide 102 is provided to the resonator 141 via the optical coupler 105 and the second waveguide 103. Accordingly, in the signal detection mode, both the light received via the optical receiver 130 and the light generated from the light source 110 are provided to the resonator 141. In that case, the signal measured by the photodetector 143 is a signal of interference light formed by the interference between the received light received via the optical receiver 130 and the transmitted light generated from the light source 110.

[0082] Thereby, the processor 150 can analyze the frequency of the received signal and calculate information about the object in front by the FMCW (frequency modulated continuous wave) method. For example, FIG. 11 is a graph exemplarily showing the frequency component of the transmitted light and the frequency component of the received light in the triangular FMCW method. In FIG. 11, the vertical axis represents frequency, and the horizontal axis represents time. As shown in FIG. 11, the graphs of the transmitted light and the received light show a triangular form in which the frequency increases linearly with time and then decreases linearly again. There is a time delay of about Δt between the frequency peak of the transmitted light and the frequency peak of the received light. According to the FMCW method, using the signal of the interference light measured by the photodetector 143, the processor 150 can calculate the time delay Δt between the frequency peak of the transmitted light and the frequency peak of the received light, and through this, accurately calculate the distance information to the object in front and the relative speed information with the object in front. Although FIG. 11 exemplarily shows the triangular FMCW method, it is also possible to use the linear FMCW method.

[0083] In the above-described embodiment, it was described that the light source 110 is a pulse light source and the processor 150 calculates information about the object in front by the TOF method. However, in the embodiment shown in FIG. 10, in order to use the FMCW method, the light source 110 is also a continuous wave light source that continuously oscillates and generates continuous light having a waveform such as a sine wave. Further, the processor 150 controls the light source 110 so that the light source 110 generates frequency-modulated light as shown in FIG. 11. Even when the FMCW method is used, the wavelength change of the frequency-modulated light is very small, for example, about 0.006 nm. Therefore, both the minimum wavelength and the maximum wavelength of the frequency-modulated light can satisfy the resonance condition of the resonator 141.

[0084] FIG. 12 is a block diagram schematically showing the configuration of a rider device according to still another embodiment. Referring to FIG. 12, the rider device 100e may include a first waveguide 102 disposed between a light source 110 and an optical transmitter 120, without including an optical switch 101, an optical coupler 105 disposed on the first waveguide 102, and a second waveguide 103 disposed between the optical coupler 105 and a resonator 141. For example, the first end of the first waveguide 102 is directly connected to the light source 110, and the second end is directly connected to the optical transmitter 120. Also, the first end of the second waveguide 103 is connected to the optical coupler 105, and the second end passes in a direction parallel to the tangential direction of the resonator 141 in the vicinity of the resonator 141.

[0085] In the embodiment shown in FIG. 12, when switching between the tuning mode and the signal detection mode, optical switching is not required. In the tuning mode, a part of the light generated from the light source 110 is provided to the resonator 141 via the optical coupler 105 and the second waveguide 103. In the tuning mode, the processor 150 interrupts the operation of the optical transmitter 120. Also, in the signal detection mode, the resonator 141 is provided with not only the light received via the optical receiver 130 but also the light generated from the light source 110. In that case, the signal measured by the photodetector 143 is a signal of interference light formed by the interference between the received light received via the optical receiver 130 and the transmitted light generated from the light source 110. The processor 150 can analyze the frequency of the received signal and calculate information about the object ahead by the FMCW method.

[0086] FIG. 13 is a block diagram schematically showing the configuration of a rider device according to still another embodiment. The configuration of the rider device 100f shown in FIG. 13 is similar to the configuration of the rider device 100e shown in FIG. 12, except that only the direction in which light travels in the resonator 141 is different. For example, in the case of the rider device 100e shown in FIG. 12, in the resonator 141, the transmitted light travels in the counterclockwise direction, and the received light travels in the clockwise direction. Conversely, in the case of the rider device 100f shown in FIG. 13, in the resonator 141, the transmitted light travels in the clockwise direction, and the received light travels in the counterclockwise direction. Therefore, in the rider device 100f shown in FIG. 13, the second waveguide 103 passes in a direction parallel to the tangent direction of the resonator 141 in the vicinity of the resonator 141 after being bent by 180°. The third waveguide 104 also passes in a direction parallel to the tangent direction of the resonator 141 in the vicinity of the resonator 141 after being bent by 180°.

[0087] FIG. 13 shows both the second waveguide 103 and the third waveguide 104 bent by 180°, but is not necessarily limited thereto. For example, only the second waveguide 103 may be bent by 180°, or only the third waveguide 104 may be bent by 180°. When only one of the second waveguide 103 and the third waveguide 104 is bent by 180°, the transmitted light and the received light travel in the same direction in the resonator 141. Even when the transmitted light and the received light travel in the same direction in the resonator 141, an interference signal between the transmitted light and the received light may be generated.

[0088] So far, the resonator of the resonant optical detection module has been exemplified as a closed curve waveguide resonator, but is not necessarily limited thereto. For example, FIG. 14 is a block diagram schematically showing the configuration of a rider device according to still another embodiment. Referring to FIG. 14, the resonant optical detection module 140d of the rider device 100g may include a loop mirror resonator 141c. The loop mirror resonator 141c includes a first loop mirror 146 and a second loop mirror 147 formed on the waveguide.

[0089] The first loop mirror 146 and the second loop mirror 147 are configured to bend a partial section of the waveguide into a loop form so that a part of the waveguide faces each other closely. In the narrow neck portion between the first loop mirror 146 and the second loop mirror 147 where a part of the waveguide faces each other closely, partial reflection and partial transmission occur. Therefore, since the effect of light resonance occurs between the first loop mirror 146 and the second loop mirror 147, the first loop mirror 146 and the second loop mirror 147 can serve as a resonator. The phase modulator 142 and the photodetector 143 are arranged on the waveguide between the first loop mirror 146 and the second loop mirror 147 where resonance occurs.

[0090] In the embodiment shown in FIG. 14, the second waveguide 103, the loop mirror resonator 141c, and the third waveguide 104 may be integrally configured using one waveguide. For example, one waveguide extends from the optical switch 101 to the optical receiver 130, and the first loop mirror 146 and the second loop mirror 147 are formed in the middle portion of the waveguide. In FIG. 14, for convenience, the section between the optical switch 101 and the first loop mirror 146 is indicated by the second waveguide 103, and the section between the optical receiver 130 and the second loop mirror 147 is indicated by the third waveguide 104.

[0091] On the other hand, when the optical transmitter 120 and the optical receiver 130 are implemented by an optical phased array (OPA) method, the optical transmitter 120 and the optical receiver 130 can be integrated and configured in one chip. Also, the optical transmitter 120, the optical receiver 130, and the resonant photodetection module 140 may be integrated in one chip, and further, the light source 110, the optical transmitter 120, the optical receiver 130, and the resonant photodetection module 140 can be integrated in one chip. Therefore, if the optical transmitter 120 and the optical receiver 130 are implemented by the optical phased array (OPA) method, the lidar device can be made very small.

[0092] For example, FIG. 15 is a perspective view schematically showing an exemplary configuration of an optical phased array element. Referring to FIG. 15, the optical phased array element 200 includes a substrate 201, a light source 110 disposed on the substrate 201, a branching region 200A, a phase control region 200B, an amplification region 200C, and an emission region 200D. The light source 110, the branching region 200A, the phase control region 200B, the amplification region 200C, and the emission region 200D are arranged along a first direction DR1. The optical phased array element 200 includes a plurality of waveguides 211 that sequentially transmit the light generated from the light source 110 to the branching region 200A, the phase control region 200B, the amplification region 200C, and the emission region 200D. The light generated from the light source 110 travels along the first direction DR1 through the waveguide 211. In FIG. 15, the light source 110 is exemplarily shown as being fabricated integrally with the optical phased array element 200, but the light source 110 may be fabricated separately from the optical phased array element 200.

[0093] The branching region 200A includes a plurality of splitters 220. The plurality of splitters 220 divide one light traveling along the waveguide 211 into a plurality of lights. For this purpose, one waveguide 211 is connected to the input end of each splitter 220, and a plurality of waveguides 211 are connected to the output end. Exemplarily, FIG. 15 shows a plurality of splitters 220 that divide one light into two lights. The light generated from the light source 110 is split into a plurality of lights within the branching region 200A. The plurality of split lights each travel along a plurality of waveguides 211. In FIG. 15, the light generated from the light source 110 is shown as being split into eight lights in the branching region 200A, but this is a simple example and is not necessarily limited thereto.

[0094] The phase control region 200B includes a plurality of phase control elements 230 respectively disposed in a plurality of waveguides 211. For example, the plurality of phase control elements 230 are arranged along a second direction DR2 perpendicular to the first direction DR1. The plurality of lights branched in the branching region 200A are respectively provided to the plurality of phase control elements 230. The phase control element 230 has a variable refractive index that is electrically controlled. The refractive index of the phase control element 230 determines the phase of the light passing through the phase control element 230. The phase control element 230 can independently adjust the phases of the plurality of branched lights.

[0095] The amplification region 200C includes a plurality of optical amplifiers 240 respectively disposed in a plurality of waveguides 211. The plurality of optical amplifiers 240 are arranged along a second direction DR2 perpendicular to the first direction DR1. The optical amplifier 240 increases the magnitude of the optical signal. For example, each optical amplifier 240 includes a semiconductor optical amplifier or an ion-doping amplifier.

[0096] The emission region 200D includes a plurality of grating pattern groups 250. The plurality of grating pattern groups 250 are arranged along the second direction DR2. The plurality of grating pattern groups 250 are respectively connected to the plurality of optical amplifiers 240. Each grating pattern group 250 emits the light amplified in the amplification region 200C respectively. For this purpose, each grating pattern group 250 includes a plurality of grating patterns 250a arranged periodically. The plurality of grating patterns 250a are arranged along the first direction DR1. The traveling direction of the output light OL emitted by the grating pattern group 250 is determined by the phase difference between the divided lights determined in the phase control region 200B, the interval between the grating patterns 250a, the height of the grating patterns 250a, and the width of the grating patterns 250a. For example, the traveling direction of the output light OL has a component in the first direction DR1, a component in the second direction DR2, and a component in a third direction DR3 perpendicular to both the first direction DR1 and the second direction DR2.

[0097] When the optical phased array element 200 shown in FIG. 15 is used as an optical transmitter, the processor 150 can control a plurality of phase control elements 230 independently and adjust the phases of the branched plurality of lights, so as to adjust the azimuth direction of the transmitted light emitted through the grating pattern group 250. For example, due to the phase differences set for the plurality of phase control elements 230, the transmitted light is radiated in different azimuth directions. On the other hand, the elevation angle direction of the signal light emitted through the grating pattern group 250 can be realized by changing the wavelength of the light source 110. For example, in the wavelength band of 1,310 nm, when the wavelength changes by 10 nm, the elevation angle changes by about 2°.

[0098] Also, the optical phased array element 200 shown in FIG. 15 can also be used as an optical receiver. In that case, the optical phased array element 200 operates in the reverse manner to the optical transmitter. For example, when light is input through the grating pattern group 250, the processor 150 can preliminarily adjust the phases of the plurality of phase control elements 230 so as to match the direction in which the light input is expected. The light incident from the direction set by the processor 150 is combined into one waveguide through the plurality of phase control elements 230 and becomes constructive interference, and is detected by the photodetector, while the light incident from a direction that does not match the set direction becomes destructive interference while being combined into one waveguide through the plurality of phase control elements 230 and is not detected by the photodetector.

[0099] FIG. 16 is a block diagram schematically showing the configuration of a lidar device including the optical phased array element shown in FIG. 15. The lidar device 100h shown in FIG. 16 has substantially the same configuration as the lidar device 100 shown in FIG. 1, and is different in that it includes an optical transmitter 120a and an optical receiver 130a, which are simply composed of an optical phased array element 200. Further, the lidar device 100h includes one substrate 121 on which a light source 110, an optical transmitter 120a, an optical receiver 130a, and a resonant optical detection module 140 are all mounted. The optical transmitter 120a includes a plurality of phase control elements 124 and a plurality of grating pattern groups 126, and the optical receiver 130a also includes a plurality of phase control elements 134 and a plurality of grating pattern groups 136. The configuration including the optical phased array element is applicable not only to the lidar device 100 shown in FIG. 1 but also to the lidar devices according to all the above-described embodiments.

[0100] The lidar device 100h can perform two-dimensional scanning on the front region using the optical transmitter 120a and the optical receiver 130a. For example, FIG. 17 illustratively shows the distribution of the signal light emitted from the lidar device 100h shown in FIG. 16. As shown in FIG. 17, the lidar device 100h can sequentially scan from the first azimuth direction θ1 to the Nth azimuth direction θ N while fixing the first elevation angle direction φ1. As described above, the azimuth angle is controlled through the plurality of phase control elements 124, and the elevation angle is determined by the wavelength of the light generated from the light source 110. The processor 150 controls the light source 110 so that the light source 110 generates light of the first wavelength λ1 in order to emit light in the first elevation angle direction φ1.

[0101] Thereafter, the lidar device 100h adjusts the elevation angle direction to the second elevation angle direction φ2. To that end, the processor 150 controls the light source 110 so that the light source 110 generates light of the second wavelength λ2. Then, the processor 150 controls the phase control elements 124, and from the first azimuth direction θ1 to the Nth azimuth direction θ NIt can be sequentially scanned up to. In such a manner, each time the elevation angle direction is changed, the wavelength of the light generated from the light source 110 changes. Therefore, each time the elevation angle direction is changed, the lidar device 100h can perform a tuning mode of controlling the phase modulator 142 of the resonant optical detection module 140 to match the resonant wavelength of the resonator 141 with the wavelength of the light generated from the light source 110.

[0102] For example, FIG. 18 illustratively shows the driving method of the lidar device 100h shown in FIG. 16. Referring to FIG. 18, the processor 150 controls the light source 110 so that the light source 110 generates light of the first wavelength λ1 in order to emit light in the first elevation angle direction φ1. In the tuning mode, the light of the first wavelength generated from the light source 110 is provided to the resonator 141, and the phase modulator 142 is controlled to adjust the phase of the light traveling along the resonator 141, thereby matching the resonant wavelength of the resonator 141 with the first wavelength. Then, in the signal detection mode, while the processor 150 provides the light of the first wavelength generated from the light source 110 to the optical transmitter 120a, the processor 150 controls a plurality of phase control elements 124 to change the azimuth angle direction of the light emitted from the optical transmitter 120a from the first azimuth angle direction θ1 to the Nth azimuth angle direction θ N sequentially up to.

[0103] When the scanning for the first elevation angle direction φ1 is completed, the processor 150 controls the light source 110 so that the light source 110 generates light of the second wavelength λ2 in order to emit light in the second elevation angle direction φ2. In the tuning mode, the light of the second wavelength generated from the light source 110 is provided to the resonator 141, and the phase modulator 142 is controlled to adjust the phase of the light traveling along the resonator 141, thereby matching the resonant wavelength of the resonator 141 with the second wavelength. Then, in the signal detection mode, while the processor 150 provides the light of the second wavelength generated from the light source 110 to the optical transmitter 120a, the processor 150 controls a plurality of phase control elements 124 to change the azimuth angle direction of the light emitted from the optical transmitter 120a from the first azimuth angle direction θ1 to the Nth azimuth angle direction θ N sequentially up to.

[0104] In addition, when using an optical phased array device, it is also possible to fabricate the above-described optical transmitter 120a and optical receiver 130a integrally coupled as one optical transceiver. For example, FIG. 19 is a block diagram schematically showing the configuration of a lidar device according to still another embodiment. Referring to FIG. 19, the lidar device 100i includes a light source 110, an optical transceiver 125, and a resonant optical detection module 140. The optical transceiver 125 is composed of an optical phased array device and can perform both the roles of an optical transmitter and an optical receiver.

[0105] In addition, the lidar device 100i includes a first waveguide 102 disposed between the light source 110 and the optical transceiver 125, a second waveguide 103 disposed between the light source 110 and the resonator 141 of the resonant optical detection module 140, a third waveguide 104 disposed between the optical transceiver 125 and the resonator 141, an optical switch 101 that provides the light generated from the light source 110 to the first waveguide 102 or the second waveguide 103 under the control of the processor 150, and an optical coupler 105 disposed on the first waveguide 102. The first end of the third waveguide 104 is connected to the optical coupler 105. The optical coupler 105 transmits the light coming from the first waveguide 102 to the optical transceiver 125 and transmits the light received from the optical transceiver 125 to the third waveguide 104.

[0106] FIG. 20 is a block diagram schematically showing the configuration of a lidar device according to still another embodiment. Referring to FIG. 20, the lidar device 100j includes a light source 110, an optical transceiver 125, and a resonant optical detection module 140. In addition, the lidar device 100j includes an optical circulator 106 that outputs the light input to the first port to the second port and outputs the light input to the second port to the third port, a first waveguide 102 connected between the light source 110 and the first port of the optical circulator 106, an optical coupler 105 disposed on the first waveguide 102, a second waveguide 103 connected between the resonator 141 and the optical coupler 105, and a third waveguide 104 connected between the resonator 141 and the third port of the optical circulator 106.

[0107] The light generated from the light source 110 is branched by the optical coupler 105 and supplied to the resonator 141 and the first port of the optical circulator 106. The light supplied to the first port of the optical circulator 106 is output to the second port and transmitted to the optical transceiver 125. Also, the light received by the optical transceiver 125 is input to the second port of the optical circulator 106 and output to the third port of the optical circulator 106. Then, the light output to the third port of the optical circulator 106 is provided to the resonator 141 via the third waveguide 104. Therefore, the signal light and the received light are simultaneously provided to the resonator 141, and the lidar device 100j shown in FIG. 20 can calculate information about a forward object, for example, in an FMCW method.

[0108] The above-described lidar device can be configured to extract distance and relative speed information from a vehicle in front, for example, when mounted on a vehicle. However, the lidar device according to the present embodiment is not necessarily applicable only to vehicles. For example, the lidar device can also be mounted on ships, aircraft, etc. other than vehicles, or on drones, etc., and can also be used to search for and avoid obstacles in front of ships, aircraft, drones, etc.

[0109] The above-described lidar device having an improved SNR has been described with reference to the embodiments shown in the drawings, but these are merely exemplary, and those having ordinary knowledge in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the disclosed embodiments should be considered from an explanatory perspective rather than a limiting perspective. The scope of rights is represented not by the above description but by the claims, and all differences within the equivalent scope should be construed as being included in the scope of rights.

Industrial Applicability

[0110] The present invention is applicable to, for example, the technical field related to autonomous driving.

Explanation of Signs

[0111] 100 Rider device 101 Optical switch 102 First waveguide 103 Second waveguide 104 Third waveguide 110 Light source 120 Optical transmitter 130 Optical receiver 140 Resonant optical detection module 141 Resonator 142 Phase modulator 143 Photodetector 150 Processor 160 Optical system 161 Band - pass filter Object in front of OBJ

Claims

1. A light source that generates light, An optical transmitter that emits the light generated from the light source to the outside, An optical receiver that receives light from the outside, A resonant optical detection module that selectively amplifies and detects light having the same wavelength as the light generated from the light source among the light received by the optical receiver, A processor that controls the light source and the resonant optical detection module, and includes, The resonant optical detection module includes, A resonator, A phase modulator that is disposed on the resonator and adjusts the phase of the light traveling along the resonator based on the control of the processor, An optical detector that detects the intensity of the light traveling along the resonator, A first waveguide disposed between the light source and the optical transmitter, A second waveguide disposed between the light source and the resonator, A third waveguide disposed between the optical receiver and the resonator, A light switch that provides the light generated from the light source to the first waveguide or the second waveguide under the control of the processor, and further includes a lidar device.

2. The processor, Before providing the light generated from the light source to the optical transmitter, first provide it to the resonator, By controlling the phase modulator and adjusting the phase of the light traveling along the resonator, the resonant wavelength of the resonator is made to coincide with the wavelength of the light generated from the light source, The lidar device according to claim 1, wherein after determining the resonant wavelength of the resonator, the light generated from the light source is provided to the optical transmitter.

3. The processor, while controlling the phase modulator and adjusting the phase of the light traveling along the resonator, determines that the resonant wavelength of the resonator coincides with the wavelength of the light generated from the light source when the intensity of the light detected by the optical detector reaches the maximum. The lidar device according to claim 2, characterized in that.

4. Further includes a temperature sensor that measures the temperature of the light source, The processor, Determines the wavelength of the light generated from the light source based on the temperature measured by the temperature sensor, If the wavelength of the light generated from the light source changes by more than a predetermined range, the phase modulator is controlled to adjust the phase of the light traveling along the resonator, so that the resonant wavelength of the resonator is made to coincide with the wavelength of the light generated from the light source. The lidar device according to claim 2, characterized in that.

5. The lidar device according to claim 1, further comprising an additional photodetector connected to the end of the third waveguide for measuring the intensity of external noise.

6. further comprising an optical coupler disposed on the first waveguide, one end of the second waveguide extends to the optical coupler, and a part of the light provided to the optical transmitter via the first waveguide is provided to the resonator via the optical coupler and the second waveguide. The lidar device according to claim 1, characterized in that

7. the light source is a continuous wave light source that generates continuous wave light, the processor controls the light source so that the light source generates frequency-modulated light, and extracts distance information and velocity information about an external object by an FMCW (frequency modulated continuous wave) method. The lidar device according to claim 6, characterized in that

8. A light source that generates light, an optical transmitter that emits the light generated from the light source to the outside, a photodetector that receives light from the outside, a resonant optical detection module that selectively amplifies and detects light having the same wavelength as the light generated from the light source among the light received by the photodetector, a processor that controls the light source and the resonant optical detection module, the resonant optical detection module includes a resonator, a phase modulator disposed on the resonator for adjusting the phase of the light traveling along the resonator based on the control of the processor, a photodetector for detecting the intensity of the light traveling along the resonator, the resonator includes a first resonator and a second resonator having different optical path lengths and optically connected to each other, the phase modulator includes a first phase modulator disposed on the first resonator for adjusting the phase of the light traveling along the first resonator based on the control of the processor, and a second resonator disposed on the second resonator. A second phase modulator that adjusts the phase of the light traveling along the resonator based on the control of the processor, the photodetector includes a first photodetector that detects the intensity of the light traveling along the first resonator and a second photodetector that detects the intensity of the light traveling along the second resonator. A lidar device characterized by

9. the processor first provides the light generated from the light source to the first resonator before providing it to the optical transmitter. By controlling the first phase modulator and adjusting the phase of the light traveling along the first resonator, the resonance wavelength of the first resonator is made to coincide with the wavelength of the light generated from the light source. By controlling the second phase modulator and adjusting the phase of the light traveling along the second resonator, the resonance wavelength of the second resonator is made to coincide with the wavelength of the light generated from the light source. The lidar device according to claim 8, further comprising providing the light generated from the light source to the optical transmitter after determining the resonance wavelengths of the first resonator and the second resonator.

10. A first waveguide disposed between the light source and the optical transmitter; A second waveguide disposed between the light source and the first resonator; A third waveguide disposed between the optical receiver and the second resonator; The lidar device according to claim 8, further comprising an optical switch that provides the light generated from the light source to the first waveguide or the second waveguide under the control of the processor.

11. A light source that generates light; An optical transmitter that emits the light generated from the light source to the outside; An optical receiver that receives light from the outside; A resonant optical detection module that selectively amplifies and detects light having the same wavelength as the light generated from the light source among the light received by the optical receiver; A processor that controls the light source and the resonant optical detection module, The resonant optical detection module includes: A resonator; A phase modulator disposed on the resonator and adjusting the phase of the light traveling along the resonator based on the control of the processor; A photodetector that detects the intensity of the light traveling along the resonator, A first waveguide disposed between the light source and the optical transmitter; An optical coupler disposed on the first waveguide; A second waveguide disposed between the optical coupler and the resonator; A third waveguide disposed between the optical receiver and the resonator, The lidar device, wherein a part of the light provided to the optical transmitter through the first waveguide is provided to the resonator through the optical coupler and the second waveguide.

12. The lidar device according to claim 1, wherein the resonator is a closed-loop waveguide resonator.

13. A light source that generates light; An optical transmitter that emits the light generated from the light source to the outside; An optical receiver that receives light from the outside; A resonant optical detection module that selectively amplifies and detects light having the same wavelength as the light generated from the light source among the light received by the optical receiver. A processor that controls the light source and the resonant optical detection module. The resonant optical detection module includes: A resonator; A phase modulator disposed on the resonator and configured to adjust the phase of light traveling along the resonator based on the control of the processor; A photodetector configured to detect the intensity of light traveling along the resonator. The resonator includes a first loop mirror and a second loop mirror formed on a waveguide. The phase modulator and the photodetector are disposed on the waveguide between the first loop mirror and the second loop mirror. A lidar device characterized by this.

14. A first waveguide disposed between the light source and the optical transmitter; A second waveguide disposed between the light source and the first loop mirror; A third waveguide disposed between the optical receiver and the second loop mirror; The lidar device according to claim 13, further comprising an optical switch that provides light generated from the light source to the first waveguide or the second waveguide under the control of the processor.

15. The lidar device according to claim 1, wherein the optical transmitter and the optical receiver are optical phased array (OPA) elements.

16. The optical transmitter includes: A substrate; A waveguide disposed on the substrate; A plurality of distributors each including an input end connected to one waveguide and an output end connected to a plurality of waveguides; A plurality of phase control elements configured to independently adjust the phases of a plurality of lights branched by the plurality of distributors; The lidar device according to claim 15, further comprising a plurality of grating pattern groups each connected to the plurality of phase control elements and configured to emit a plurality of lights with adjusted phases.

17. The lidar device according to claim 16, wherein the light source, the optical transmitter, the optical receiver, and the resonant optical detection module are all disposed on one substrate.

18. The processor: Controls the plurality of phase control elements and adjusts the phases of the branched plurality of lights, thereby adjusting the azimuth direction of the light emitted from the optical transmitter. The lidar device according to claim 16, wherein the elevation angle direction of the light emitted from the optical transmitter is adjusted by adjusting the wavelength of the light generated from the light source.

19. The lidar device according to claim 18, wherein each time the elevation angle direction of the light emitted from the optical transmitter is changed, the processor controls the phase modulator to match the resonance wavelength of the resonator with the wavelength of the light generated from the light source.

20. A light source that generates light, An optical transmitter that emits the light generated from the light source to the outside, An optical receiver that receives light from the outside, A resonant optical detection module that selectively amplifies and detects light having the same wavelength as the light generated from the light source among the light received by the optical receiver, A processor that controls the light source and the resonant optical detection module, The resonant optical detection module includes A resonator, A phase modulator that is disposed on the resonator and adjusts the phase of the light traveling along the resonator based on the control of the processor, A photodetector that detects the intensity of the light traveling along the resonator, The optical transmitter and the optical receiver are optical phased array (OPA) elements, The optical transmitter includes A substrate, A waveguide disposed on the substrate, A plurality of distributors each including an input end connected to one waveguide and an output end connected to a plurality of waveguides, A plurality of phase control elements that independently adjust the phases of the plurality of lights branched by the plurality of distributors, A plurality of grating pattern groups each connected to the plurality of phase control elements and emitting the plurality of lights whose phases are adjusted, The processor Controls the plurality of phase control elements and adjusts the phases of the branched plurality of lights to adjust the azimuth angle direction of the light emitted from the optical transmitter, Adjusts the elevation angle direction of the light emitted from the optical transmitter by adjusting the wavelength of the light generated from the light source, Each time the elevation angle direction of the light emitted from the optical transmitter is changed, the processor controls the phase modulator to match the resonance wavelength of the resonator with the wavelength of the light generated from the light source, The processor Controls the light source so that the light source generates light having a first wavelength, Provides the light having the first wavelength generated from the light source to the resonator, By controlling the phase modulator and adjusting the phase of the light traveling along the resonator, the resonance wavelength of the resonator is made to coincide with the first wavelength. While providing the light of the first wavelength generated from the light source to the optical transmitter, the plurality of phase control elements are controlled to adjust the azimuthal direction of the light emitted from the optical transmitter. The light source is controlled so that the light source generates light of a second wavelength. The light of the second wavelength generated from the light source is provided to the resonator. By controlling the phase modulator and adjusting the phase of the light traveling along the resonator, the resonance wavelength of the resonator is made to coincide with the second wavelength. A lidar device, characterized in that while providing the light of the second wavelength generated from the light source to the optical transmitter, the plurality of phase control elements are controlled to adjust the azimuthal direction of the light emitted from the optical transmitter.

21. The lidar device according to claim 15, characterized in that the optical transmitter and the optical receiver are an integrally coupled optical transceiver.

22. A light source that generates light, An optical transmitter that emits the light generated from the light source to the outside, An optical receiver that receives light from the outside, A resonant optical detection module that selectively amplifies and detects light having the same wavelength as the light generated from the light source among the light received by the optical receiver, A processor that controls the light source and the resonant optical detection module, and includes: The resonant optical detection module includes: A resonator, A phase modulator disposed on the resonator and adjusting the phase of the light traveling along the resonator based on the control of the processor, A photodetector that detects the intensity of the light traveling along the resonator, and includes: The optical transmitter and the optical receiver are optical phased array (OPA) elements. The optical transmitter and the optical receiver are an integrally coupled optical transceiver. A first waveguide disposed between the light source and the optical transceiver, A second waveguide disposed between the light source and the resonator, A third waveguide disposed between the optical transceiver and the resonator, An optical switch that provides the light generated from the light source to the first waveguide or the second waveguide under the control of the processor, An optical coupler disposed on the first waveguide, and includes: A lidar device, characterized in that one end of the third waveguide is connected to the optical coupler, and the optical coupler transmits the light received by the optical transceiver to the third waveguide.

23. A light source that generates light, An optical transmitter that emits the light generated from the light source to the outside, A light receiver that receives light from the outside, A resonant optical detection module that selectively amplifies and detects light having the same wavelength as the light generated from the light source among the light received by the light receiver, A processor that controls the light source and the resonant optical detection module, and includes, The resonant optical detection module is A resonator, A phase modulator that is disposed on the resonator and adjusts the phase of the light traveling along the resonator based on the control of the processor, A photodetector that detects the intensity of the light traveling along the resonator, and includes, The optical transmitter and the optical receiver are optical phased array (OPA; optical phase array) elements, The optical transmitter and the optical receiver are an integrally coupled optical transceiver, An optical circulator that outputs the light input to the first port to the second port and outputs the light input to the second port to the third port, A first waveguide connected between the light source and the first port of the optical circulator, An optical coupler disposed on the first waveguide, A second waveguide connected between the resonator and the optical coupler, A third waveguide connected between the third port of the optical circulator and the resonator, and includes, A lidar device, characterized in that the optical transceiver is connected to the third port of the optical circulator.

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