Optical antennas, optical phased array transmitters, and lidar systems

Abstract

This invention provides an optical antenna (300), an optical phased array transmitter, and a lidar system using the above-described device. The optical antenna (300) includes a substrate forming at least a portion of a reflective layer (310) having a first material; a waveguide layer (350) disposed above the reflective layer (310) and comprising a second material; and a separator layer (330) disposed between the waveguide layer (350) and the reflective layer (310) and comprising a third material. The waveguide layer (350) also has a first grating array (359). The reflective layer (310) is used to reflect light emitted downwards from the waveguide layer (350). The refractive index of the third material is less than that of the first or second material.

Description

Technical Field

[0001] This invention relates to an optical antenna, an optical phased array (OPA) transmitter, and a lidar system using the above-mentioned devices, and more particularly to a mobile vehicle using an OPA lidar system for distance sensing, environmental mapping, and obstacle detection. Background Technology

[0002] Distance sensing and environmental mapping have recently become a hot research area with various industrial applications. For example, they can help safety systems detect suspicious approaching objects and help drones or robots perceive their surroundings, estimate distances to objects, and avoid them. However, the largest and most important potential application is in autonomous driving, as autonomous driving requires vehicles to sense distances and obstacles (pedestrians, other vehicles, roadblocks, trees, etc.) to replace human drivers in complex road conditions.

[0003] To achieve this, a time-of-flight device is often used. A time-of-flight device measures the time required for a wave (such as sound waves and electromagnetic waves) to traverse the distance between itself and an object. Equipped with a receiver, it can receive the wave reflected from the object, and given the wave speed, calculate the distance between itself and the object, thus determining its spatial position. Common time-of-flight devices include ultrasonic ranging devices and radar. Recently, devices using LiDAR (Light Detection and Ranging) technology have been applied to the field of autonomous driving. LiDAR uses pulsed lasers to measure the distance between itself and a large number (typically millions or more) of points in three-dimensional (3D) space to obtain this distance and information about the object's 3D appearance in 3D space.

[0004] Most commercially available LiDAR systems are currently mechanical LiDARs, employing a high-speed rotating LiDAR scanner that can emit laser light into the surrounding environment with a 360° field of view. However, mechanical LiDARs are prone to mechanical failures, which reduces reliability and lifespan. They are also very bulky, requiring installation on vehicle roofs, resulting in an unsightly appearance that is less appealing to potential users.

[0005] With the development of LiDAR technology, solid-state LiDAR has been introduced as an alternative device. Its compact and inexpensive features meet the needs of mid-range sensing and environmental mapping in autonomous driving. Solid-state LiDAR features a photonic integrated circuit (PIC) that emits a laser beam from a semiconductor component into the environment. Through polarizing components (such as collimators) configured in the LiDAR, the laser beam can be controlled to be emitted in various directions, thus eliminating the need to rotate the LiDAR scanner. After the laser beam reaches the target and is reflected, the LiDAR's optical receiver receives the beam and converts the optical signal into an electronic signal for subsequent processing. The LiDAR's processing electronics convert the electronic signal into a point cloud for reconstructing a 3D representation of the environment, including rendering individual sensed targets.

[0006] For various reasons, solid-state lidar, especially OPA lidar, is still under development and not yet fully commercialized. One of the biggest obstacles for OPA lidar compared to mechanical lidar is its lower light emission efficiency, thus requiring higher power; otherwise, the accuracy of reception and data processing would be reduced. Therefore, there is a need for a high-efficiency optical antenna, an OPA transmitter, and a lidar system using these components, all of which should reduce energy loss to enable the commercialization of solid-state lidar. Summary of the Invention

[0007] This invention relates to optical transmission devices. Specifically, such devices may include optical antennas, OPA transmitters, and lidar systems using the aforementioned devices.

[0008] In one aspect, embodiments of the present invention provide an optical antenna for optical transmission. The optical antenna includes a substrate forming at least a portion of a reflective layer containing a first material; a waveguide layer disposed above the reflective layer and containing a second material; and a separator layer disposed between the waveguide layer and the reflective layer and containing a third material. The waveguide layer also has a first grating array. The reflective layer is used to reflect light emitted downwards from the waveguide layer. The refractive index of the third material is less than that of the first or second material.

[0009] On the other hand, embodiments of the present invention provide an OPA transmitter. The OPA transmitter includes a light source; a beam splitter for optically coupling to the light source and for splitting a beam emitted by the light source into multiple beams; a phase shifter for optically coupling to the beam splitter and having multiple channels; and an optical antenna for optically coupling to the phase shifter and having multiple transmitters. Each transmitter further includes a substrate forming at least a portion of a reflective layer containing a first material; a waveguide layer disposed above the reflective layer, containing a second material and having a first grating array; and a separating layer disposed between the waveguide layer and the reflective layer and containing a third material. The reflective layer is used to reflect light emitted downwards from the waveguide layer. The refractive index of the third material is less than the refractive index of the first or second material.

[0010] In another aspect, embodiments of the present invention provide a lidar system. The lidar system includes an OPA transmitter comprising a first optical antenna having a plurality of transmitters; an OPA receiver comprising a second optical antenna having a plurality of receiving elements; system electronics; and a power supply. Each transmitter and receiving element further includes a substrate forming at least a portion of a reflective layer containing a first material; a waveguide layer disposed above the reflective layer, containing a second material and having a first grating array; and a separating layer disposed between the waveguide layer and the reflective layer, containing a third material. The reflective layer is used to reflect light emitted downwards from the waveguide layer. The refractive index of the third material is less than that of the first or second material.

[0011] It is understood that the above overview and the following detailed description are for illustrative and explanatory purposes only, and are not intended to limit the scope of the invention claimed. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of an exemplary OPA transmitter 100 provided in some embodiments of the present invention;

[0013] Figure 2 This is a cross-sectional view of the existing optical antenna 200;

[0014] Figure 3 This is a cross-sectional view of an optical antenna 300 provided in some embodiments of the present invention;

[0015] Figure 4 This is a cross-sectional view of an optical antenna 400 provided in some embodiments of the present invention;

[0016] Figure 5 This is a cross-sectional view of an optical antenna 500 provided in some embodiments of the present invention;

[0017] Figure 6 This is a cross-sectional view of an optical antenna 600 provided in some embodiments of the present invention;

[0018] Figure 7 This is a cross-sectional view of an optical antenna 700 provided in some embodiments of the present invention;

[0019] Figure 8 This is a schematic diagram of an exemplary lidar system 800 provided in some embodiments of the present invention. Detailed Implementation

[0020] Please now refer to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. All drawings will use the same or similar reference numerals to denote the same or similar parts wherever possible.

[0021] Figure 1 This is a schematic diagram of an exemplary OPA transmitter 100 provided in some embodiments of the present invention. The OPA transmitter 100 is a key component of a solid-state lidar system because it can provide a phased-array laser beam to the outside of the lidar system, allowing the beams to interfere with each other and ultimately form a far-field pattern. Light can be projected onto objects to be detected in the environment. In this embodiment, the OPA transmitter 100 can be a PIC manufactured using semiconductor manufacturing technology (e.g., CMOS manufacturing technology). A PIC is an integrated circuit with two or more photonic functions. For example, the OPA transmitter 100 can generate a laser, split the laser beam and emit it into different channels, phase-shift the split laser beam, or emit the laser beam outside the OPA transmitter 100.

[0022] In some embodiments of the present invention, the OPA transmitter 100 may include a light source, such as a laser 101. The laser 101 may be assembled on the same PIC chip as other components of the OPA transmitter 100, or it may be configured externally to the PIC chip via a guide channel. The laser 101 may emit laser light by amplifying light based on stimulated emission of electromagnetic radiation. Preferably, the laser 101 provided in the embodiments of the present invention may be a semiconductor laser, which generates a laser beam at the junction of a laser diode when voltage-driven electrons descend from a higher energy level to a lower energy level and recombine with a hole, thereby generating radiation in the form of emitted photons.

[0023] The laser generated by laser 101 is not necessarily limited to the visible spectrum, whose wavelengths are typically between 380 and 740 nm. Instead, since current semiconductor lasers can generate laser beams with wavelengths between the infrared and ultraviolet spectra, the laser 101 provided by this invention can provide lasers with wavelengths in a broader spectrum than the visible spectrum, for example, lasers with wavelengths between approximately 200 and 3000 nm. Therefore, the broader emitted laser spectrum allows for greater flexibility in lidar design and sometimes reduces side effects on the human body. For example, infrared light with wavelengths between approximately 1400 and 1800 nm is safe for the eyes because it is difficult for the eyes to absorb. Infrared light is also suitable for high-power operation. The longer the wavelength of the laser beam, the lower the requirements for semiconductor manufacturing technology, because many device parameters are proportional to the wavelength of the laser beam. However, lasers with wavelengths greater than 3000 nm can cause corneal damage under extreme conditions, and therefore may not be suitable for autonomous driving, as their beams would constantly illuminate pedestrians and other drivers. On the other hand, lasers with wavelengths shorter than approximately 200 nm may require a reduction in the size of other lidar components, including, for example, waveguides. Manufacturing waveguides, based on existing semiconductor manufacturing technologies, can be costly or very difficult. However, this should not prevent those skilled in the art from applying the spirit of this invention to future products compatible with wavelengths longer or shorter than the aforementioned range, where the manufacturing process can mitigate or eliminate the aforementioned problems.

[0024] As used in this invention, the term "approximate" refers to the value of a given quantity that can vary based on a specific technology node associated with the semiconductor device in question. Based on that specific technology node, the term "approximate" can refer to the value of a given quantity that can vary within a certain range, for example, within the range of 5–30% of that value (e.g., ±5%, ±10%, ±20%, or ±30% of that value).

[0025] In some embodiments of the present invention, the OPA transmitter 100 may include a beam splitter 102. The beam splitter 102 may be optically coupled to a laser 101. The meaning of "optically coupled to" or "optically coupled to" as used in the present invention is that when two or more components are connected through a path that can penetrate electromagnetic waves, an optical flow (including but not limited to ultraviolet light, visible light, and infrared light) will occur.

[0026] Beam splitter 102 can split an input laser beam into N laser beams for phase shifting, where N is equal to or greater than 2. The split laser beams are an important operation in a lidar system because multiple laser beams, after being phase-shifted and emitted into the environment, may interfere with each other, thus forming a new directional beam pattern that can be projected onto an object as a highly concentrated beam for reflection and reception. Examples of beam splitters 102 provided in this embodiment include star couplers, multimode interference (MMI) tree couplers, etc. A star coupler can have at least one input terminal and multiple output terminals. Each input terminal corresponds to N output terminals, where N is typically a power of 2, so the split beams can be equally distributed and therefore have the same characteristics. MMI tree couplers may be stronger in achieving uniform phase delay of the laser beam, but they are generally more complex to manufacture on a PIC chip compared to star couplers.

[0027] In some embodiments, the beam splitter 102 can be mounted on the same chip as other downstream components, including phase shifters, transmitters, etc., on which the PIC chip is mounted. In other embodiments, the beam splitter 102 can be mounted on the same chip as the laser 101, and can be integrated with or separated from the chip containing these downstream components.

[0028] In some embodiments of the present invention, the OPA transmitter 100 may be equipped with a phase shifter 103 having two or more channels. The phase shifter 103 may be optically coupled to a beam splitter 102. Assuming that the beam splitter 102 has N output terminals, the number of channels of the phase shifter 103 may preferably be designed to be equal to the number of output terminals, that is, also designed to be N, so that each channel is dedicated to performing a phase shifting operation on a split beam. In some embodiments, the phase shifter 103 may have 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024 channels, all of which are powers of 2. Each channel may shift the phase of a split beam by a predetermined offset, with the aim of enabling multiple laser beams emitted from the lidar to interfere with each other and ultimately form a predictable far-field pattern. Preferably, the phase shifter 103 may be mounted on a PIC chip and used as a transmitter to reduce power loss during the transmission of the laser beam from the phase shifter to the transmitter.

[0029] Interference occurs when two or more electromagnetic waves (e.g., the laser provided in this invention) are superimposed to form a new wave. When the original waves originate from the same source or have the same or nearly the same frequency, the resulting new wave may produce constructive or destructive interference, depending on the phase difference. If the amplitude of the synthesized new wave is greater than that of the original wave, constructive interference occurs, resulting in a stronger wave. Conversely, if the amplitude of the synthesized new wave is less than that of the original wave, destructive interference occurs, resulting in a weaker wave. For example, if the phase difference between the two superimposed waves is an even multiple of 180º (or π), constructive interference is at its peak level; if the phase difference is an odd multiple of 180º (or π), destructive interference is at its peak level (i.e., the minimum amplitude after interference). In this invention, the emitted laser beam exhibits far more constructive interference than destructive interference, thus not only expanding the detection range of the lidar but also making it easier for the lidar receiver to capture reflected light.

[0030] In some preferred embodiments, phase shifter 103 may employ one or more tunable phase shifters. Tunable phase shifters allow the designer or user of the lidar system to fine-tune the amount of phase shift in the split laser beam array to control the direction and far-field pattern of the superimposed beam emitted from the lidar. Tuning can be implemented and optimized through software programming, for example, using simulation algorithms to simulate the true result of the interferogram (i.e., the image or pattern projected onto an object at a distance due to interference). Software such as MATLAB (e.g., v9.5) developed by MathWorks may be required. System electronics may also be needed. Figure 1 (Not shown in the image), the phase shifter 103 is controlled electronically to perform phase shifting. Such system electronics can be provided on the same PIC chip that provides the phase shifter 103 using known semiconductor manufacturing techniques (e.g., CMOS manufacturing processes), and therefore will not be described further here.

[0031] In some embodiments of the present invention, the OPA transmitter 100 may be fitted with an optical antenna 104 having one or more transmitters. The optical antenna 104 may be optically coupled to a phase shifter 103. Assuming that the phase shifter 103 has N channels, the number of transmitters in the optical antenna 104 may preferably be designed to be equal to the number of channels in the phase shifter 103, i.e., also designed to be N, with each transmitter dedicated to transmitting a split beam. Similar to the phase shifter 103, the optical antenna 104 may be manufactured using semiconductor manufacturing techniques (e.g., CMOS manufacturing techniques).

[0032] Since the beam splitter 102, phase shifter 103, and optical antenna 104 together constitute an array optical device that can be used to control the phase and amplitude of the beam 105 emitted outside the lidar system, they can be collectively referred to as an "optical phased array device" according to the present invention. Once optically coupled to the laser 101, the optical phased array device can become the aforementioned OPA transmitter 100.

[0033] Figure 2 This is a cross-sectional view of an existing optical antenna 200. The optical antenna 200 is designed to be mounted on a semiconductor chip and is capable of emitting light into the external environment. For ease of reference, in... Figure 2 Two directions, the x-direction and the y-direction, are highlighted to further illustrate the spatial relationships between the components in the optical antenna 200. The optical antenna 200 consists of four layers, namely layers 202, 204, 206, and 208, which extend in the x-direction (i.e., lateral) and are stacked vertically in the y-direction (i.e., vertical). In this invention, whether a component (e.g., element, layer, or device) of a semiconductor device (e.g., an optical antenna) is located "above," "above," or "below" another component (e.g., element, layer, or device), or whether light is emitted "up," "up," "up," "down," "down," or "down" by the component (e.g., element, layer, or device), is determined relative to the position of the substrate of the semiconductor device (e.g., substrate 202, discussed below) in the y-direction (i.e., vertical) if the substrate is positioned on the lowest plane of the semiconductor device in the y-direction. The same concept is applied in describing spatial relationships in this invention.

[0034] A thin oxide layer is disposed between the waveguide optical antennas 200, the bottom of which includes a substrate 202. The substrate 202 is made of silicon. A buried oxide layer 204 is disposed on top of it. The buried oxide layer 204 is made of silicon dioxide (also known as silicon dioxide). This structure, consisting of a silicon layer and a silicon dioxide layer stacked together, has been used by lidar developers in the industry when building photonic semiconductor systems and is called a silicon insulator (“SOI”) structure. The optical antenna 200 also includes a waveguide layer 206 and a cladding layer 208 disposed on top of the waveguide layer 206. The cladding layer 208 can be used to protect the internal structure of the optical antenna 200. The waveguide layer 206, as its name suggests, functions to guide the light emitted from other components of the lidar system and project it into the environment. A grating array is inserted into the waveguide layer 206 to deflect the light emitted from the waveguide layer 206 upwards and downwards.

[0035] A problem with the existing design of the optical antenna 200 is that it suffers from significant inherent energy loss when emitting light. This loss can reach 3 dB or more, primarily caused by downward-emitted light that is absorbed by or passes through the substrate 202. Therefore, lidar systems cannot use downward-emitted light for optical interference and projection. Thus, a solution is needed to improve the efficiency of the optical antenna used in lidar systems, preferably employing a simple manufacturing process.

[0036] Figure 3 This is a cross-sectional view of an optical antenna 300 provided in some embodiments of the present invention. The optical antenna 300 is a chip-level semiconductor device (e.g., a PIC) mounted in a lidar system for optical transmission. It can be optically coupled to other components on the device, such as those described above. Figure 1 The beam splitter and phase shifter described herein. In some embodiments, the optical antenna 300 may have the same number of transmitters as the number of channels of the phase shifter, wherein one transmitter corresponds to one channel of the phase shifter. In this configuration, each transmitter of the optical antenna 300 receives a split laser beam emitted through the corresponding channel of the phase shifter.

[0037] It is worth noting that, Figure 3 This is only a cross-sectional view of the internal components of one transmitter of the optical antenna 300. In some preferred embodiments, the multiple transmitters of the optical antenna 300 may be constructed identically to the transmitter shown, with all transmitters extending laterally (along the x-direction) in a plane (not shown) of the PIC. This plane is perpendicular to the y-direction. The transmitters of the optical antenna 300 may be parallel or nearly parallel to each other along the x-direction to avoid crosstalk between different transmitters. Crosstalk occurs when a signal transmitted by one channel is affected by signals transmitted by adjacent channels, typically caused by capacitive, inductive, or conductive coupling. To further reduce the probability of crosstalk, the channel spacing... d p (That is, the distance between two adjacent emitters) can be designed to be greater than the wavelength λ of the transmitted beam. In a non-limiting example, when λ ranges from approximately 0.8 μm to 1.8 μm, d p It's likely between approximately 0.5λ and 5λ. (Length of the optical antenna) l It can range from approximately 0.1 mm to 10 mm, depending on the application and the manufacturing technology used.

[0038] In some embodiments of the present invention, the optical antenna 300 may include a reflective layer 310, a waveguide layer 350 disposed above the reflective layer 310, and a separating layer 330 disposed between the reflective layer 310 and the waveguide layer 350. The reflective layer 310 can reflect the light 354 emitted downward from the waveguide layer 350, thereby reducing energy loss due to unintended light scattering and increasing the intensity of the emitted light 352 emitted upward from the optical antenna 300. Compared to conventional lidar systems using the same light source, lidar systems using the optical antenna provided by the present invention have higher emission efficiency and a wider detection range.

[0039] The waveguide layer 350 provided by this invention has two main functions: guiding light through the optical antenna 300 and simultaneously emitting light to the outside of the optical antenna 300. The thickness of the waveguide layer 350 along the y-direction can be 100 to 1000 nm. It can be made of one or more of silicon, polycrystalline silicon, silicon nitride, or other high-refractive-index materials (refractive index at least higher than silicon dioxide). When the refractive index of the material used in this layer is higher than that of the materials used in the layers covering the waveguide layer 350, more light may be reflected back to the waveguide layer 350, while the opposite is not possible (i.e., using a material with a lower refractive index to make the waveguide layer 350). Moreover, under certain conditions, it also makes it possible to guide light inside the waveguide layer 350 through total internal reflection. When the incident light of a wave (e.g., light) at the interface between two media (typically from a high-refractive-index medium to a low-refractive-index medium) exceeds the critical angle... θ c At this critical angle, total internal reflection occurs, causing all light rays to be reflected back into the high-refractive-index medium. θ c The calculation can be performed using the following equation (1).

[0040] Equation (1)

[0041] Where n2 is the refractive index of the second medium, and n1 is the refractive index of the first medium. Table 1 below shows the refractive indices of some exemplary materials applicable to this invention.

[0042]

[0043] Table 1 Approximate Refractive Indices of Applicable Materials

[0044] It is important to note that the refractive index value of each material may vary depending on the measurement method and the wavelength of the electromagnetic wave. Therefore, the refractive index values ​​listed above are only approximate. Those skilled in the art understand how to measure the true refractive index value between two selected media for electromagnetic waves having a predetermined wavelength λ through a limited number of experiments.

[0045] An isotropic waveguide layer can emit light upwards through partial refraction. However, the intensity of partially refracted light is often far lower than that required to form a far-field pattern (e.g., a light spot). Therefore, a grating array is inserted into the waveguide layer to increase the light emission intensity. According to some embodiments of the invention, the waveguide layer 350 may include an intermittent grating array having a plurality of gratings 359, all inserted between waveguide material 357, such as... Figure 3 As shown. The grating 359 can be fabricated using silicon dioxide or other similar materials with a lower refractive index than the waveguide material 357 (which can be one or more of silicon, polycrystalline silicon, silicon nitride, or other high-refractive-index materials (with a refractive index at least higher than silicon dioxide)). The grating array can be fabricated using an etching process, in which a uniform waveguide layer is first formed using chemical precipitation, then etched using a mask covering the waveguide material, and finally the etched holes are filled with grating material. The waveguide layer 350 can be designed by controlling the spacing of the grating array (i.e., the average width of a combination of a grating 359 and a waveguide material 357) and the duty cycle (i.e., the ratio of the average width of a grating 359 in one direction to the spacing in the same direction) to obtain the desired emitted beam angle and improved emission efficiency.

[0046] This invention provides a non-limiting example of a grating array for waveguide layer 350, with a spacing of 0.5λ to λ and a duty cycle of 0.4 to 0.6, where λ is the wavelength of the split beam. Since the wavelength λ provided by this invention is approximately between 800 and 1800 nm, the spacing can range from approximately 400 to 1800 nm. It is worth noting that the spacing and duty cycle of each pair of gratings and waveguide material are not necessarily uniform across the entire length of waveguide layer 350. Other ranges of spacing or duty cycle may also yield substantially the same favorable results repeatedly through this invention.

[0047] In some embodiments, the reflective layer 310 may include a substrate 312 and a buried oxide layer 314 disposed above the substrate 312. The substrate 312 may be made of silicon, and the buried oxide layer 314 may be made of silicon dioxide (also known as silica). This structure, known as an SOI structure, allows optical antenna manufacturers to more easily achieve mass production based on commercially available wafers. It is worth noting that the materials used to fabricate the substrate 312 and the buried oxide layer 314 are not limited to the examples given above. Other materials may also be used, and the same or similar results can be achieved by combining them with the guidance of this invention.

[0048] According to some embodiments of the present invention, the reflective layer 310 may further include a reflective waveguide structure 316. The reflective waveguide structure 316 may be arranged above the buried oxide layer 314 and below the waveguide layer 350. The main function of the reflective waveguide structure 316 is to reflect downward-emitted light 354 back to the upper surface of the optical antenna 300 to form reflected light 356, thereby increasing the intensity of the beam emitted by the lidar system. In some preferred embodiments, the reflective waveguide structure 316 may further include an intermittent grating array having multiple gratings 319, all inserted between the reflective waveguide material 317. Figure 3 The illustrated embodiment shows the spatial spacing and alignment of the grating and waveguide materials in the x-direction. The grating 319 can be made of silicon dioxide or other similar materials with a lower refractive index than the reflector waveguide material 317 (which can be one or more of silicon, polycrystalline silicon, silicon nitride, or other high-refractive-index materials (with a refractive index at least higher than silicon dioxide)). Similar to the waveguide layer 350, the reflective waveguide structure 316 can be designed to adjust the angle of the upwardly reflected beam by controlling the spacing and duty cycle of the grating array, thus improving the transmission efficiency of the optical antenna 300.

[0049] A non-limiting example provided in this invention offers a grating array suitable for use in a reflective waveguide structure, wherein the grating array has a spacing between 0.25λ and 0.75λ and a duty cycle between 0.3 and 0.7, where λ is the wavelength of the split beam. Since the wavelength λ provided by this invention is approximately between 800 and 1800 nm, the spacing can range from approximately 200 to 1350 nm. It is noteworthy that the spacing and duty cycle of each pair of gratings and waveguide material are not necessarily uniform over the entire length of the reflective waveguide structure 316. Other ranges of spacing or duty cycle may also be applicable to this invention and may yield substantially the same favorable results.

[0050] In some embodiments, the separator layer 330 may be a thin film disposed above the reflective layer 310 and extending laterally on a plane of the PIC, wherein the plane is perpendicular to the y-direction. The refractive index of the material of the separator layer 330 in this invention is lower than that of the waveguide material 357 of the waveguide layer 350 and the reflector waveguide material 317 of the reflective layer 310. Therefore, the separator layer 330 may be made of silicon dioxide or other low-refractive-index materials (with a refractive index at least lower than that of silicon nitride). The silicon dioxide used in the separator layer 330 may be pure silicon dioxide or doped silicon dioxide. For example, fluorine-doped silicon dioxide may have a lower refractive index than pure silicon dioxide.

[0051] According to some embodiments of the present invention, the thickness of the separator layer 330 should be designed and manufactured to facilitate enhancing the intensity and range of the beam emitted by the optical antenna 300. In particular, the thickness of the separator layer 330 may be such that constructive interference occurs between the emitted light 352 and the reflected light 356. This is because such a thickness allows for an optical path difference PD between the optical path length (OPL) of the emitted light 352 and the optical path length (OPL) of the reflected light 356, thereby generating a new combined beam with a larger amplitude than the original beam when constructive interference occurs between the two beams. The emitted light 352 and the reflected light 356 have the same wavelength λ originating from the light source. Figure 3 (Not shown in the image). When the optical path difference PD When the value is an even multiple of 180º (or π) multiplied by the wavelength λ, the new beam formed by the combination can have the maximum amplitude under the condition of constructive interference, as shown in equation (2) below.

[0052] Equation (2)

[0053] Where k is 0, 1, 2, 3, ..., n. In some applications where maximum amplitude is not required, the optical path difference can be selected. PD falls within a certain range, thus An enhanced amplitude (i.e., greater than the single amplitude of the emitted light 352 or the reflected light 356) can be obtained. For example, this range could be... to .

[0054] It is worth noting that the thickness calculation of the separator layer 330 described above may not have taken into account some factors that could also affect the phase change between the emitted light 352 and the reflected light 356. These include, for example, the incident and reflection angles of the reflected light 356, and the refractive index of the separator layer 330 (FDTD or MODE application package version developed by Lumerical Inc.). Such applications allow those skilled in the art, in conjunction with the guidance of this invention, to determine the appropriate thickness (or thickness range) of the separator layer 330 to enhance the emission intensity of the lidar system at the desired location in space. In a non-limiting example, where the wavelength of the light is 1550 nm, the thickness of the separator layer 330 made of silicon dioxide could be approximately 1500 nm, based on simulation results obtained using the FDTD or MODE application package.

[0055] In some further embodiments, the optical antenna 300 may also include a cladding layer 390 disposed above the waveguide layer 350. The cladding layer 390 protects the main components of the optical antenna 300, namely the waveguide layer 350, the separator layer 330, and the reflective layer 310, from corrosion or damage upon direct exposure. It also acts as a light-transmitting layer, allowing light emitted from below to pass through. Therefore, the material chosen for the cladding layer 390 can be a transparent material capable of transmitting emitted light with a specific wavelength λ (which is also the wavelength of the light source in the lidar system). For example, silicon dioxide transmits light with a wavelength of 1550 nm; therefore, if the wavelength of the light generated by the lidar light source is 1550 nm, silicon dioxide can be used as the material for the cladding layer 390. In another example, the cladding layer 390 can be made of a polymer material, such as benzocyclobutene (BCB). As shown in Table 1, the refractive indices of both silicon dioxide and polymer materials are less than the refractive index of waveguide material 357. Waveguide material 357 can be one or more of silicon, polycrystalline silicon, silicon nitride, or other high refractive index materials (with a refractive index at least higher than that of silicon dioxide).

[0056] Figure 4 This is a cross-sectional view of an optical antenna 400 provided in some embodiments of the present invention. The components, design, and function of the optical antenna 400 are generally the same as or similar to those of the optical antenna 300, with one main difference, which will be described below.

[0057] The optical antenna 400, as a chip-level semiconductor device, can be optically coupled to other components (e.g., beam splitters, phase shifters, etc.) and can receive the split beam of light that is further emitted outside the lidar system. Figure 4As shown, the optical antenna 400 may also include a reflective layer 410, a waveguide layer 450 disposed above the reflective layer 410, and a separator layer 430 disposed between the reflective layer 410 and the waveguide layer 450. The waveguide layer 450 may include an intermittent grating array comprising multiple gratings 459 inserted between waveguide materials 457. Furthermore, the waveguide layer can deflect the input beam upwards to become light 452 and downwards to become light 454. The reflective layer 410 may include a substrate 412, a buried oxide layer 414 disposed above the substrate 412, and a reflective waveguide structure 416 disposed above the buried oxide layer 414. The reflective waveguide structure 416 can reflect light 456 back to the upper surface of the optical antenna 400, making it light 456. Therefore, when constructive interference occurs between light 456 and light 452, the intensity of the beam emitted by the lidar system can be enhanced. The separator layer 430 is similar to the separator layer 330 of the optical antenna 300; its thickness should be sufficient to allow constructive interference between the emitted light 452 and the reflected light 456. (The above is combined with...) Figure 3 The calculation and simulation methods for the thickness of the separator layer 330 described in the embodiments can also be applied to the separator layer 430. The optical antenna 400 may also include a cladding layer 490 disposed above the waveguide layer 450. Figure 4 The materials used to manufacture the components listed above, using numerical designations, can be compared with... Figure 3 The components with the same number in the optical antenna 300 listed herein are made of the same material.

[0058] The main difference between optical antenna 400 and optical antenna 300 lies in the reflective waveguide structure of the reflective layer. As described above, in optical antenna 300, the grating 319 and reflector waveguide material 317 of the reflective waveguide structure 316 are approximately aligned along the x-direction. Conversely, in optical antenna 400, the grating and waveguide material of the reflective waveguide structure 416 are approximately aligned along the y-direction. More specifically, the reflective waveguide structure 416 may include an intermittent grating array having multiple gratings 419 inserted between the reflector waveguide materials 417, wherein each grating 419 and each waveguide material 417 are stacked perpendicularly to each other to form a thin film, such as... Figure 4As shown. The vertically stacked grating array of the reflective waveguide structure 416 can be formed by continuously chemically depositing thin films of waveguide material 417 and grating 419 in an interleaved manner. This manufacturing process differs from the etching process used to fabricate the intermittent grating array in the optical antenna 300. Grating 419 can be made of silicon dioxide or other similar materials with a lower refractive index than waveguide material 417 (which can be one or more of silicon, polycrystalline silicon, silicon nitride, or other high refractive index materials (with a refractive index at least higher than silicon dioxide)). Therefore, light 454 can be partially or completely reflected back from the interface between the reflective waveguide material 417 and grating 419. When the incident angle of light 454 is greater than the critical angle... θ c When this occurs, total internal reflection will happen. Similar to waveguide layer 450, the reflective waveguide structure 416 can be designed by controlling the spacing and duty cycle of the grating array to adjust the angle of the beam reflected upward and improve the emission efficiency.

[0059] According to one example of the present invention, the reflective waveguide structure 416 may include three layers of reflective waveguide material 417 and two layers of gratings 419. The thickness of each layer of reflective waveguide material 417 is between 50 nm and 500 nm, and the thickness of each layer of grating 419 is between 50 nm and 500 nm. Those skilled in the art can, in conjunction with the guidance of the present invention, use simulation software applications (e.g., the latest version of the FDTD or MODE application package developed by Lumerical Inc.) to design the appropriate number of layers of reflective waveguide material 417 and grating 419, as well as the appropriate thickness (or thickness range) of each layer of reflective waveguide material 417 and grating 419.

[0060] Figure 5 This is a cross-sectional view of an optical antenna 500 provided in some embodiments of the present invention. Similar to optical antennas 300 and 400, the optical antenna 500 provided by the present invention may include a reflective layer 510, a waveguide layer 550 disposed above the reflective layer 510, and a separator layer 530 disposed between the reflective layer 510 and the waveguide layer 550. The waveguide layer 550 may include an intermittent grating array, which includes a plurality of gratings 559 inserted between waveguide materials 557. The waveguide layer may also deflect an input beam upward to become light 552 and deflect an input beam downward to become light 554.

[0061] According to some embodiments consistent with the present invention, the reflective layer 510 of the optical antenna 500 may include a substrate 512 and a metal reflector 513. The material of the metal reflector 513 may include one or more of gold, silver, aluminum, or other metals or alloys capable of reflecting light 554 back to the upper surface of the optical antenna 500 to become light 556. Therefore, although the reflective layer 510 has a different construction, its function is the same as that of the reflective layers 310 and 410 in the previous embodiments. Because the metal reflector 513 can reflect light 554 without absorbing its energy, the emission efficiency of the optical antenna 500 may be higher than in other embodiments using grating arrays in the reflective layer. An exemplary manufacturing process for the metal reflector 513 includes first etching a portion of the substrate 512 from the bottom up to the separator layer 530 and then forming a thin film of the metal plate by chemical deposition. Therefore, the manufacturing process may be more complex than the manufacturing processes used to manufacture the grating arrays in the reflective layers 310 and 410.

[0062] Similar to the separator layer 330 of optical antenna 300 and the separator layer 430 of optical antenna 400, the separator layer 530 may have a thickness sufficient to allow constructive interference between the emitted light 552 and the reflected light 556. (The above is combined with...) Figure 3 The calculation and simulation methods for the thickness of the separator layer 330 described in the embodiments can also be applied to the separator layer 530. The optical antenna 500 may also include a cladding layer 590 disposed above the waveguide layer 550. Figure 5 The materials used to manufacture the components listed above, using numerical designations, can be compared with... Figure 3 and Figure 4 The optical antennas 300 and 400 listed herein are made of the same material.

[0063] Figure 6 This is a cross-sectional view of an optical antenna 600 provided in some embodiments of the present invention. Similar to optical antennas 300, 400, and 500, optical antenna 600 may also include a reflective layer 610, a waveguide layer 650 disposed above the reflective layer 610, and a separating layer 630 disposed between the reflective layer 610 and the waveguide layer 650. Optical antenna 600 may also include a cladding layer 690 disposed above the waveguide layer 650, which serves as a light-transmitting layer and may be fabricated using one or more of silicon dioxide or polymer materials.

[0064] Although not in Figure 6 As shown, but the structure of the reflective layer 610 can be the same as... Figure 3 , 4The reflective layer 610 has the same construction as the reflective layers 310, 410, or 510 described in section 5. In some embodiments, the reflective layer 610 may include sublayers that facilitate light reflection, such as a substrate, a buried oxide layer, a reflective waveguide structure (such as the reflective waveguide structure in optical antenna 300 or 400), a metal reflector (such as the metal reflector in optical antenna 500), etc. In other embodiments, the reflective layer 610 may be uniformly formed from a single substrate, which may be made of silicon or polysilicon, although the light reflection capability in these embodiments may not be as good as that in embodiments including multiple sublayers.

[0065] In some embodiments of the present invention, the waveguide layer 650 of the optical antenna 600 may include a waveguide sublayer 651, a high refractive index layer 655 disposed above the waveguide sublayer 651, and a thin oxide layer 653 disposed between the waveguide sublayer 651 and the high refractive index layer 655, such as Figure 6 As shown. The optical antenna 600 differs from the prior art and other embodiments described above in that it intentionally couples light between the two light-guiding layers (i.e., waveguide sub-layer 651 and high-refractive-index layer 655), which contradicts the conventional concept of avoiding crosstalk. More specifically, both waveguide sub-layer 651 and high-refractive-index layer 655 can use a thin layer of sub-wavelength thickness located between them to transmit the split beam received by the optical antenna 600.

[0066] In this embodiment, waveguide sublayer 651 can be fabricated using silicon, polycrystalline silicon, silicon nitride, or other high-refractive-index materials (refractive index at least higher than that of silicon dioxide). Unlike waveguide layers 350, 450, and 550 in the preceding embodiments, Figure 6 The waveguide sublayer 651 shown does not have a grating array. Since the refractive indices of the materials of the separator layer 630 and the thin oxide layer 653 are both lower than those of the waveguide sublayer 651, light can be confined and transmitted within the waveguide sublayer 651 by total internal reflection, thereby reducing losses caused by unnecessary light scattering.

[0067] The high-refractive-index layer 655 can be constructed similarly to waveguide layers 350, 450, and 550. For example... Figure 6 As shown, the high refractive index layer 655 may include an intermittent grating array, which includes a plurality of gratings 659 inserted between waveguide materials 657, such as Figure 6As shown. Grating 659 can be fabricated using silicon dioxide or other similar materials with a lower refractive index than waveguide material 657 (which can be one or more of silicon, polycrystalline silicon, silicon nitride, or other high-refractive-index materials (with a refractive index at least higher than silicon dioxide)). By controlling the spacing and duty cycle of the grating array, waveguide layer 650 can be designed to achieve the desired emitted beam angle and improved emission efficiency. Consistent with these embodiments, the preferred spacing range is about 400 to 1800 nm, and the preferred duty cycle range is about 0.2 to 0.8.

[0068] In these embodiments, the thickness of the thin oxide layer 653 can be designed to be equal to the subwavelength to allow coupling between the light transmitted through the waveguide sublayer 651 and the light transmitted through the high-refractive-index layer 655. The thin oxide layer 653 can be fabricated using silicon dioxide or one or more other low-refractive-index materials (refractive index at least lower than that of silicon nitride). In some preferred embodiments, the thickness of the thin oxide layer 653 can be between about 50 and 400 nm, which is less than half the wavelength of a typical light source in a lidar system, such as 905 nm or 1550 nm. The thin oxide layer 653 can be fabricated using a thermal oxidation process, which is performed at high temperatures (typically between 800 and 1200°C) by adding an oxidant to a silicon wafer, causing a reaction that forms an oxide layer on its surface. Thermal oxidation is a standard process in CMOS manufacturing and is therefore a simple and economical process that can be employed in this invention. When light in the high-refractive-index layer 655 and light in the waveguide sublayer 651 couple with each other due to their proximity, the intensity of the light emitted from the optical antenna 600 is enhanced. The degree of this enhancement can be controlled by designing the thickness of the thin oxide layer 653 using analog software applications known in the lidar industry (e.g., the latest version of the FDTD or MODE application package developed by Lumerical Inc.). Similar to the design of the separator layers 330, 430, and 530, such applications allow those skilled in the art, in conjunction with the guidance of this invention, to determine the appropriate thickness (or thickness range) of the thin oxide layer 653, thereby enhancing the emission intensity of the lidar system at desired locations in space.

[0069] In some embodiments, the physical properties and materials of the separator 630 may be similar to those of the separators 330, 430, and 530 described above. It may be made using one or more of silicon dioxide or other low-refractive-index materials (refractive index at least lower than that of silicon nitride). The separator 630 may have a thickness sufficient to allow constructive interference between the emitted light 652 and the reflected light 656 (formed by the light 654 emitted downwards from the reflective waveguide layer 650). (The above is in conjunction with...) Figure 3The calculation and simulation methods for the thickness of the separator layer 330 described in the embodiments can also be applied to the separator layer 630.

[0070] Figure 7 This is a cross-sectional view of an optical antenna 700 provided in some embodiments of the present invention. The optical antenna 700 may include a reflective layer 710, a waveguide layer 750 disposed above the reflective layer 710, and a separating layer 730 disposed between the reflective layer 710 and the waveguide layer 750. The waveguide layer 750 may further include a waveguide sub-layer 751, a high refractive index layer 755 disposed above the waveguide sub-layer 751, and a thin oxide layer 753 disposed between the waveguide sub-layer 751 and the high refractive index layer 755, such as... Figure 7 As shown. The high refractive index layer 755 may include an interpolated grating array comprising a plurality of gratings 759 inserted between waveguide materials 757. The separator layer 730 should have a thickness sufficient to allow constructive interference between emitted light 752 and reflected light 756 (formed by light 754 emitted downward from the reflective waveguide layer 750). The optical antenna 700 may also include a cladding layer 790 disposed above the waveguide layer 750, which acts as a light-transmitting layer and may be fabricated using one or more of silicon dioxide or polymer materials. The physical characteristics, design, and function of these components of the optical antenna 700 may be the same as or similar to the physical characteristics, design, and function of components of the optical antenna 600 with similar reference numerals described above.

[0071] The main difference between optical antenna 700 and optical antenna 600 is that waveguide sublayer 751 may also include an intermittent grating array comprising a plurality of gratings 749 inserted between waveguide material 747. This configuration is similar to... Figure 3 , 4 The grating arrays in waveguide layers 350, 450, and 550 are shown in Figures 5 and 6, respectively. By controlling the spacing and duty cycle of the grating arrays in waveguide sublayer 751 and high-refractive-index layer 755, waveguide layer 750 can be designed to obtain the desired emitted beam angle and improved emission efficiency. Consistent with these embodiments, for high-refractive-index layer 755, the preferred spacing range is about 400 to 1800 nm, and the preferred duty cycle range is about 0.2 to 0.8; for waveguide sublayer 751, the preferred spacing range is about 400 and 1800 nm, and the preferred duty cycle range is about 0.4 to 0.6. According to these embodiments, with Figure 6 Compared to the embodiments described herein, the transmission efficiency can be further enhanced, but the manufacturing process may be more complex and therefore potentially more expensive, partly due to the addition of an additional grating array in waveguide layer 750. Those skilled in the art will understand how to choose an optical antenna design that best suits their budget and functional requirements.

[0072] Figure 8 This is a schematic diagram of an exemplary lidar system 800 provided in some embodiments of the present invention. The lidar system 800 may include an OPA transmitter 820, an OPA receiver 840, system electronics 860, and a power supply 880. The OPA transmitter 820 may be constructed similarly to the one described above. Figure 1 The exemplary OPA transmitter 100 described herein has the same construction and may include one or more optical antennas with the same construction as any of the exemplary optical antennas 300, 400, 500, 600, and 700. In addition to the embodiments described above, some embodiments of the OPA transmitter 820 may also include a lens module, which may include a global lens, multiple lenses, and / or a microlens array. The OPA transmitter can collimate the beams emitted from multiple transmitters of the optical antenna, thus correspondingly improving transmission efficiency.

[0073] Upon encountering an object 999 in space, light 825 emitted from the OPA transmitter 820 is reflected back to form light 845, which is then captured by the OPA receiver 840. In some embodiments of the invention, the OPA receiver 840 may include an optical antenna for receiving light 845. Since the reciprocity theorem applies to both light emission and reception, the design and construction of the optical antenna of the OPA receiver 840 can be identical to the design and construction of the transmitting optical antenna of the OPA transmitter 820 (including, but not limited to, exemplary optical antennas 300, 400, 500, 600, and 700). An array of light-harvesting elements, such as photodiodes or other imaging sensors that can convert photons into electrical information, may also be incorporated into the OPA receiver 840. Subsequent evaluation of the electrical information by other components of the lidar system 800 reveals that the light-harvesting elements play a crucial role in detecting the presence, direction, and possible intensity of light 845 reflected back from a distant object 999. The OPA receiver 840 may also include a lens module, which may include a global lens, multiple lenses, and / or a microlens array. This lens module can act as a color filter, natural light filter, and / or light conversion lens, allowing light to be more concentratedly projected onto each light-harvesting element.

[0074] In some embodiments, system electronics 860 may include a communication interface 861, a memory 863, a processor 865, a clock 867, and a sensor module 869. The communication interface 861 is used to transmit and receive data from the OPA transmitter 820 or the OPA receiver 840. The communication interface 861 can also exchange data with the processor 865. Such data may include clock information, system control information, data stored in the memory 863, etc.

[0075] In some embodiments, memory 863 may include any suitable mass storage device capable of storing any information that processor 865 may require for operation. Memory 863 may be transient or permanent, magnetic, semiconductor, magnetic tape, optical, removable, partially removable, or other types of storage devices or tangible (i.e., non-transitory) computer-readable media, including but not limited to read-only memory, flash memory, dynamic random access memory, and static random access memory. Memory 863 may be used to store one or more computer programs required to perform the functions of the lidar system 800 and executable by processor 865.

[0076] In some embodiments, processor 865 may include any suitable general-purpose or special-purpose microprocessor, digital signal processor, or microcontroller. Processor 865 may be configured as a separate processor module dedicated to performing one or more specific functions. Alternatively, processor 865 may be configured as a shared processor module performing other functions unrelated to one or more specific functions.

[0077] In some embodiments, clock 867 can generate a clock signal that coordinates the operation of various components in the lidar system 800, such as the phase shifter in the OPA transmitter 820, processor 865, etc. Using clock 867, system electronics 860 can calculate the phase shift between adjacent transmitters of the optical antenna in the OPA transmitter 820, and can store clock information for subsequent phase reversal when the OPA receiver 840 receives reflected light 845. Furthermore, processor 865 can calculate the distance between lidar system 800 and object 999 given the relative moving speeds, and can also calculate the travel time between transmission and emission using clock 867.

[0078] In some embodiments, sensor module 869 may include one or more sensors for informing lidar system 800 and mobile vehicles (if lidar system 800 is installed) of speed, acceleration, geographic location, etc. Sensor module 869 is crucial for automatic ranging and detecting lidar system functions, as system electronics 860 may use such information when calculating and forming point clouds. Sensor types that may be included in sensor module 869 provided by this invention may include geolocation sensors (e.g., GPS sensors, BeiDou sensors, and GLONASS sensors), inertial measurement unit (IMU) sensors, speedometers, etc.

[0079] Power supply 880 provides power to various components in lidar system 800, including OPA transmitter 820, OPA receiver 840, and system electronics 860. In some embodiments, power supply 880 may be one or more batteries installed within lidar system 800. In other embodiments, power supply 880 may be an AC or DC power source located externally to lidar system 800.

[0080] The optical antenna, OPA transmitter, and lidar system provided by this invention offer numerous advantages. The emission efficiency of the optical antenna is significantly improved and energy loss is significantly reduced because previously unused downward-emitted light can be reflected back to the upper surface of the optical antenna. Furthermore, the thickness of the separator layer in the optical antenna is designed to induce constructive interference between the emitted and reflected light, thereby improving the range and the far-field pattern of the beam emitted by the OPA transmitter. The use of widely adopted CMOS manufacturing techniques, including but not limited to etching and chemical deposition, simplifies the fabrication process for the optical antenna. Moreover, the compatibility of the SOI structure with optical antennas assembled with silicon insulator structures (e.g., silicon layers disposed on buried oxide layers) facilitates the large-scale fabrication of such optical antennas using commercially available SOI wafers.

[0081] Those skilled in the art will understand that various modifications and alterations can be made to the disclosed devices and related apparatus. Based on the specifications and practice of the disclosed devices and related apparatus, those skilled in the art will also derive other embodiments.

[0082] This specification and examples are for reference only, and their true scope is subject to the following claims and their corresponding contents.

Claims

1. An optical antenna for optical transmission, characterized in that, include: A substrate that forms at least a portion of a reflective layer, the reflective layer comprising a first material; A waveguide layer, disposed above a reflective layer, the waveguide layer being used to emit light and comprising a second material; and A separating layer, disposed between the waveguide layer and the reflective layer, the separating layer comprising a third material, wherein The waveguide layer also includes a first grating array; The reflective layer is used to reflect light emitted downwards from the waveguide layer; as well as The refractive index of the third material is lower than that of the first or second material; The waveguide layer further includes: A waveguide sublayer is disposed above the separator layer, the waveguide sublayer comprising a fourth material; A high refractive index layer, disposed above the waveguide sublayer, the high refractive index layer comprising the second material; and A thin oxide layer is disposed between the waveguide sublayer and the high refractive index layer, the thin oxide layer comprising a fifth material, wherein The first grating array is located in the high-refractive-index layer; and The refractive index of the fifth material is less than that of the second or fourth material; The waveguide sublayer does not include a grating array.

2. The optical antenna as described in claim 1, characterized in that, The wavelength range of light is 200 to 3,000 nm.

3. The optical antenna as described in claim 1, characterized in that, The thickness of the separator layer is configured to induce constructive interference between the light emitted upward from the waveguide layer and the light reflected upward from the reflective layer.

4. The optical antenna as described in claim 1, characterized in that, The spacing of the first grating array in the waveguide layer ranges from 400 to 1800 nm.

5. The optical antenna of claim 1, wherein the first grating array of the waveguide layer comprises silicon dioxide formed using an etching process.

6. The optical antenna as described in claim 1, characterized in that, The third material includes one or more of silicon dioxide or materials with a refractive index lower than that of silicon nitride.

7. The optical antenna as claimed in claim 1, characterized in that, Both the first material and the second material include one or more of silicon, polycrystalline silicon, silicon nitride, or materials with a refractive index higher than that of silicon dioxide.

8. The optical antenna as claimed in claim 1, characterized in that, It also includes a cladding layer disposed above the waveguide layer, the cladding layer comprising a light-transmitting material, wherein The refractive index of the light-transmitting material is less than that of the second material.

9. The optical antenna as described in claim 8, characterized in that, The light-transmitting material allows light transmitted in the waveguide layer to pass through.

10. The optical antenna as claimed in claim 1, characterized in that, The reflective layer also includes a metal reflective plate disposed below the separator layer.

11. The optical antenna as claimed in claim 1, characterized in that, The reflective layer further includes: A buried oxide layer is disposed above the substrate; and A reflective waveguide structure is disposed above the buried oxide layer, and the reflective waveguide structure includes a second grating array.

12. The optical antenna as claimed in claim 11, characterized in that, The second grating array is disposed above the substrate, and the second grating array comprises silicon dioxide formed using an etching process.

13. The optical antenna as claimed in claim 11, characterized in that, The second grating array is disposed above the substrate, and the second grating array comprises silicon dioxide formed using a chemical deposition process.

14. The optical antenna as claimed in claim 11, characterized in that, The second grating array includes multiple reflector waveguide materials and multiple gratings inserted between the multiple reflector waveguide materials; The waveguide layer includes an intermittent grating array, which comprises multiple gratings inserted between multiple waveguide materials, the waveguide materials being arranged in the x-direction; The reflector waveguide material is arranged in the x-direction or the y-direction, wherein the y-direction is the stacking direction of the substrate, the waveguide layer and the separator layer.

15. The optical antenna as claimed in claim 1, characterized in that, The thickness of the thin oxide layer is configured to cause coupling between the light transmitted in the waveguide sublayer and the light transmitted in the high refractive index layer.

16. The optical antenna as claimed in claim 1, characterized in that, The thin oxide layer is formed by a thermal oxidation process.

17. The optical antenna as claimed in claim 1, characterized in that, The fourth material includes one or more of silicon, polycrystalline silicon, silicon nitride, or materials with a refractive index higher than that of silicon dioxide.

18. The optical antenna as claimed in claim 1, characterized in that, The fifth material includes one or more of silicon dioxide or materials with a refractive index lower than that of silicon nitride.

19. The optical antenna as claimed in claim 1, characterized in that, The waveguide sublayer also includes a third grating array, which comprises silicon dioxide formed using an etching process.

20. An optical phased array transmitter, characterized in that, include light source; A beam splitter, optically coupled to the light source, is used to split a beam of light emitted by the light source into multiple beams. A phase shifter, optically coupled to the beam splitter, the phase shifter comprising multiple channels; and An optical antenna, optically coupled to the phase shifter and comprising a plurality of transmitters, each of the transmitters further comprising: A substrate that forms at least a portion of a reflective layer, the reflective layer comprising a first material; A waveguide layer, disposed above the reflective layer, for emitting a split beam of light, and comprising a second material; and a separator layer, disposed between the waveguide layer and the reflective layer, comprising a third material, wherein... The waveguide layer also includes a first grating array; The reflective layer is used to reflect light emitted downwards by the waveguide layer; and The refractive index of the third material is lower than that of the first material or the second material; The waveguide layer further includes: A waveguide sublayer is disposed above the separator layer, the waveguide sublayer comprising a fourth material; A high refractive index layer, disposed above the waveguide sublayer, the high refractive index layer comprising the second material; and A thin oxide layer is disposed between the waveguide sublayer and the high refractive index layer, the thin oxide layer comprising a fifth material, wherein The first grating array is located in the high-refractive-index layer; and The refractive index of the fifth material is less than that of the second or fourth material; The waveguide sublayer does not include a grating array.

21. The optical phased array transmitter as described in claim 20, characterized in that, The beam splitter, phase shifter, and optical antenna are all located on a photonic integrated circuit.

22. The optical phased array transmitter as described in claim 21, characterized in that, The light source is located on the photonic integrated circuit.

23. The optical phased array transmitter as described in claim 20, characterized in that, The number of split beams is equal to the number of channels in the phase shifter and the number of transmitters in the optical antenna.

24. The optical phased array transmitter as described in claim 20, characterized in that, The number of split beams is a power of 2.

25. The optical phased array transmitter as described in claim 20, characterized in that, The light source is a laser.

26. The optical phased array transmitter as described in claim 25, characterized in that, The wavelength range of the laser beam generated by the light source is between the infrared and ultraviolet spectra.

27. The optical phased array transmitter as described in claim 20, characterized in that, It also includes a cladding layer disposed above the waveguide layer, the cladding layer comprising a light-transmitting material, wherein The refractive index of the light-transmitting material is lower than that of the second material.

28. The optical phased array transmitter as described in claim 20, characterized in that, The reflective layer also includes a metal reflective plate disposed below the separator layer.

29. The optical phased array transmitter as described in claim 20, characterized in that, The reflective layer also includes: An embedded oxide layer is disposed above the substrate; and A reflective waveguide structure is arranged above the buried oxide layer, the reflective waveguide structure including a second grating array.

30. The optical phased array transmitter as described in claim 29, characterized in that, The second grating array includes multiple reflector waveguide materials and multiple gratings inserted between the multiple reflector waveguide materials; The waveguide layer includes an intermittent grating array, which comprises multiple gratings inserted between multiple waveguide materials, the waveguide materials being arranged in the x-direction; The reflector waveguide material is arranged in the x-direction or the y-direction, wherein the y-direction is the stacking direction of the substrate, the waveguide layer and the separator layer.

31. The optical phased array transmitter as described in claim 20, characterized in that, The thickness of the thin oxide layer is equal to the subwavelength, so that the light transmitted by the waveguide sublayer is coupled with the light transmitted by the high refractive index layer.

32. A lidar system, characterized in that, include: An optical phased array transmitter includes a first optical antenna, which includes multiple transmitters. An optical phased array receiver includes a second optical antenna, the second optical antenna including multiple receiving elements; System electronic components; And a power supply, wherein each transmitter and receiver element also includes: A substrate that forms at least a portion of a reflective layer, the reflective layer comprising a first material; A waveguide layer, disposed above the reflective layer, for emitting a split beam of light, and comprising a second material; and A separating layer, disposed between the waveguide layer and the reflective layer, the separating layer comprising a third material, wherein The waveguide layer also includes a first grating array; The reflective layer is used to reflect light emitted downwards from the waveguide layer; and The refractive index of the third material is less than that of the first material or the second material; The waveguide layer further includes: A waveguide sublayer is disposed above the separator layer, the waveguide sublayer comprising a fourth material; A high refractive index layer, disposed above the waveguide sublayer, the high refractive index layer comprising the second material; and A thin oxide layer is disposed between the waveguide sublayer and the high refractive index layer, the thin oxide layer comprising a fifth material, wherein The first grating array is located in the high-refractive-index layer; and The refractive index of the fifth material is less than that of the second or fourth material; The waveguide sublayer does not include a grating array.

33. The lidar system as described in claim 32, characterized in that, The system electronic components also include: The communication interface is used to transmit and receive data from the optical phased array transmitter and the optical phased array receiver.

34. The lidar system as described in claim 32, characterized in that, The system electronic components also include: One or more sensors are used to provide one or more types of information about the lidar system, including speed, acceleration, or geographic location.

35. The lidar system as described in claim 32, characterized in that, Includes a cladding layer disposed above the waveguide layer, the cladding layer comprising a light-transmitting material, wherein The refractive index of the light-transmitting material is less than that of the second material.

36. The lidar system as described in claim 32, characterized in that, The reflective layer also includes a metal reflective plate disposed below the separator layer.

37. The lidar system as described in claim 32, characterized in that, The reflective layer further includes: An embedded oxide layer is disposed above the substrate; and A reflective waveguide structure is disposed above the buried oxide layer, the reflective waveguide structure including a second grating array.

38. The lidar system according to any one of claims 32 to 37, characterized in that, The second grating array includes multiple reflector waveguide materials and multiple gratings inserted between the multiple reflector waveguide materials; The waveguide layer includes an intermittent grating array, which comprises multiple gratings inserted between multiple waveguide materials, the waveguide materials being arranged in the x-direction; The reflector waveguide material is arranged in the x-direction or the y-direction, wherein the y-direction is the stacking direction of the substrate, the waveguide layer and the separator layer.

39. The lidar system as described in claim 38, characterized in that, The thickness of the thin oxide layer is equal to the subwavelength, so that the light transmitted by the waveguide sublayer is coupled with the light transmitted by the high refractive index layer.

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