Photonic chip and method of forming the same

Abstract

Various embodiments may relate to a photonic chip. The photonic chip may include a substrate and a photonic circuit over the substrate. The photonic circuit may include a first optical phased array (OPA) having an output at a first edge region of the photonic chip. The photonic chip may also include a second optical phased array (OPA) having an output at a second edge region of the photonic chip different from the first edge region. The photonic circuit may further include a main multi-mode interferometer optically coupled to the first optical phased array and the second optical phased array. The photonic circuit may additionally include one or more photodetector arrays configured to detect light reflected by an object upon light from the output of the first optical phased array or the output of the second optical phased array incident onto the object.

Description

PHOTONIC CHIP AND METHOD OF FORMING THE SAMECROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of Singapore application No. 10202402295V filed August 1 , 2024, the contents of it being hereby incorporated by reference in its entirety for all purposes.TECHNICAL FIELD

[0002] Various embodiments of this disclosure may relate to a photonic chip. Various embodiments of this disclosure may relate to a method of forming a photonic chip.BACKGROUND

[0003] Light Detection and Ranging (LiDAR) system is an active remote sensing technology that uses light to measure distance, detect objects, and map three-dimensional (3D) information about an object related to its environment. As compared to Radio Detection and Ranging (RADAR) system that uses radio frequency wavelengths (> 1 mm), LiDAR uses light wave with shorter wavelengths (400 nm to several micrometers (pm)) for ranging and detection. Thus, LiDAR is able to detect objects at shorter distance (< 1 m), while RADAR is usually used for kilometer- scale applications. Due to its feasibility in high speed, short distance detection, the potential of LiDAR in autonomous driving has been widely explored. A significant success story in the field of LiDAR would be the Israel -based autonomous vehicle technology firm Mobileye, which was acquired by Intel for USD 15 billion in year 2017. In year 2022, the LiDAR market size was valued at USD 1.3 billion, and is expected to reach USD 3.5 billion by 2032.

[0004] Generally, the operation of LiDAR involves steering of a light beam across a specified field-of-view (FOV). When an object enters the FOV region of the LiDAR, the light beam hits the object and reflects towards the beam source. Dedicated photodetectors placed around the LiDAR devices would detect the reflected light. The size, shape, and distance of the object may be based on the reflected light. Accuracy of these parameters may be improved by continuous experiments and development. Traditionally, the steering of light beam is done by mechanical steering. However, mechanical steering requires bulky mechanical parts, which notonly result in large formfactor in LiDAR device, but also high manufacturing cost of LiDAR. To reduce the formfactor and the manufacturing cost, a chip-based optical phased array (OP A) based on silicon photonics technology has been developed. FIG. 1 illustrates the basic principle of an optical phased array (OP A) Fundamentally, OP A involves fiber-to-chip coupling of infrared light into the pre-fabricated silicon photonics circuit of OP A. The infrared light is then split into separated waveguide channels. For each separated waveguide channel, the phase of the infrared light is altered periodically using thermo-based or electrical-based phase shifters to achieve beam steering. In the case of FIG. 1, A<|) can be altered to 60, 90, or 180°, where a larger A(|> value corresponds to larger steering angle. The phase-shifted beams from various waveguide channels are then recombined and emitted to the free-space via grating structure or output taper. The magnitude of periodic phase-change in each waveguide channel corresponds to the steering angle.SUMMARY

[0005] Various embodiments may relate to a photonic chip. The photonic chip may include a substrate and a photonic circuit over the substrate The photonic circuit may include a first optical phased array (OP A) having an output at a first edge region of the photonic chip. The photonic chip may also include a second optical phased array (OP A) having an output at a second edge region of the photonic chip different from the first edge region. The photonic circuit may further include a main multi-mode interferometer optically coupled to the first optical phased array and the second optical phased array. The photonic circuit may additionally include one or more photodetector arrays configured to detect light reflected by an object upon light from the output of the first optical phased array or the output of the second optical phased array incident onto the object.

[0006] Various embodiments may relate to a method of forming a photonic chip. The method may include forming a photonic circuit over a substrate. The photonic circuit may include a first optical phased array having an output at a first edge region of the photonic chip. The photonic circuit may also include a second optical phased array having an output at a second edge region of the photonic chip different from the first edge region. The photonic circuit may further include a main multi-mode interferometer optically coupled to the first optical phased array and the second optical phased array. The photonic circuit may additionally include one or more photodetector arrays configured to detect light reflected by an object uponlight from the output of the first optical phased array or the output of the second optical phased array incident onto the object.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily drawn to scale, emphasis instead generally being placed upon illustrating the principles of various embodiments. In the following description, various embodiments of the invention are described with reference to the following drawings.FIG. 1 illustrates the basic principle of an optical phased array (OP A). Fundamentally, OPA involves fiber-to-chip coupling of infrared light into the pre-fabricated silicon photonics circuit of OPA.FIG. 2 shows a general illustration of the photonic chip according to various embodiments.FIG. 3 shows a general illustration of a method of forming a photonic chip according to various embodiments.FIG. 4A shows a plot of y-position (in micrometers or gm) as a function of x-position (in micrometers or pm) illustrating the two-dimensional (2D) electric field (E-field) of the emitter array including 16 emitters when A<|> = 0° according to various embodiments.FIG. 4B shows a plot of y-position (in micrometers or pm) as a function of x-position (in micrometers or pm) illustrating the two-dimensional (2D) electric field (E-field) of the emitter array including 16 emitters when Ac|> = 180° according to various embodiments.FIG. 4C shows a plot of electric field (E-field, in kilo-volts or keV) as a function of x-position (in micrometers or pm) illustrating the one-dimensional (ID) electric field at 160 pm height above the array of 16 emitters when Ac|> = 0, ° 90°, and 180° according to various embodiments. FIG. 5A shows a photonic circuit of a photonic chip according to various embodiments.FIG. 5B shows a portion (a) of the photonic circuit as illustrated in FIG. 5A according to various embodiments.FIG. 5C shows a portion (b) of the photonic circuit as illustrated in FIG. 5A including the optical phased array (OPA) according to various embodiments.FIG. 5D shows a portion (c) of the photonic circuit as illustrated in FIG. 5A including the optical phased array (OP A) outputs and photodetector (PD) arrays according to various embodiments.FIG. 5E shows a cross-sectional schematic of the photonics chip according to various embodiments.FIG. 5F shows the operation principle of the photonic chip according to various embodiments. FIG. 6 shows (a) a photonic circuit including a first optical phased array (OP A) and a second optical phased array (OP A) according to various embodiments; and (b) a photonic circuit including a first optical phased array (OP A), a second optical phased array (OP A), a third optical phased array (OP A) and a fourth optical phased array (OP A) according to various embodiments.FIG. 7 shows (a) a photonic chip with an angle between adjoining edges or edge regions of more than 90 degrees according to various embodiments; (b) a photonic chip with an angle between adjoining edges or edge regions equal to 90 degrees according to various embodiments; and (c) a photonic chip with an angle between adjoining edges or edge regions of less than 90 degrees according to various embodiments.DESCRTPTTON

[0008] The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the invention. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments

[0009] Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments. Features that are described in the context of an embodiment may correspondingly be applicable to the other embodiments, even if not explicitly described in these other embodiments. Furthermore, additions and / or combinations and / or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

[0010] In the context of various embodiments, the articles “a”, “an” and “the” as used with regard to a feature or element include a reference to one or more of the features or elements.

[0011] In the context of various embodiments, the term “about” or “approximately” as applied to a numeric value encompasses the exact value and a reasonable variance, e.g., within 10% of the specified value.

[0012] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0013] By “comprising” it is meant including, but not limited to, whatever follows the word “comprising”. Thus, use of the term “comprising” indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present.

[0014] By “consisting of’ it is meant including, and limited to, whatever follows the phrase “consisting of’. Thus, the phrase “consisting of’ indicates that the listed elements are required or mandatory, and that no other elements may be present.

[0015] Embodiments described in the context of one of the photonic chips are analogously valid for the other photonic chips. Similarly, embodiments described in the context of a method are analogously valid for a photonic chip, and vice versa

[0016] The beam steering angle of OPA has always been the main figure-of-merit in the feasibility of OPA in LiDAR application. Typically, the steering angles of OPA were -20° for phase-shifted beams emitted from grating-structured outlet. To further increase the steering angle, output tapers may be used as the beam outlets. The output tapers may be placed at the edge of the chip. Conveniently, the photodetectors integrated in the LiDAR system may also be placed at the edge of the chip, where the detection regions of the photodetectors are deep- etched to be exposed to the free space (object-detection region). At the same time, multiple OP As may be placed at adjoining or adjacent edges / sides of the photonic chip to increase the steering angle of the OPA. Various embodiments may relate to a photonic chip including off- axis multi-OPAs to achieve > 180° field of view (FOV). Photodetectors may be placed at the edge of the photonic chip with exposed detection regions to detect the size, shape, and distance of the object.

[0017] FIG. 2 shows a general illustration of the photonic chip according to various embodiments The photonic chip may include a substrate 202. The photonic chip may also include a photonic circuit 204 over the substrate 202. The photonic circuit 204 may include a first optical phased array (OPA) 204a having an output (alternatively referred to as opticalphased array output or OPA output) at a first edge region of the photonic chip 204. The photonic chip 204 may also include a second optical phased array (OPA) 204b having an output at a second edge region of the photonic chip 204 different from the first edge region. The photonic circuit 204 may further include a main multi-mode interferometer 204c optically coupled to the first optical phased array 204a and the second optical phased array 204b. The photonic circuit 204 may additionally include one or more photodetector arrays 206 configured to detect light reflected by an object upon light from the output of the first optical phased array 204a and / or the output of the second optical phased array 204b incident onto the object.

[0018] In other words, various embodiments may relate to a photonic chip including a photonic circuit 204 formed on a substrate 202. The photonic circuit 204 may include a first optical phased array 204a with an output exposed at one edge of the photonic chip, a second optical phased array 204b with an output exposed at another edge of the photonic chip, as well as a main multi-mode interferometer 204c optically coupled to the first optical phased array 204a and the second optical phased array 204b. Light may be split or separated by the main multi-mode interferometer 204c into different portions for transmission to the optical phased arrays optically coupled to the main multi-mode interferometer 204c For instance, one portion of light may travel to the first optical phased array 204a and another portion of light may travel to the second optical phased array 204b. The photonic circuit 204 may also include one or more photodetector arrays 206 to detect light(s) that is / are emitted by the output of the first optical phased array 204a and / or the output of the second optical phased array 204b and reflected by an object.

[0019] For avoidance of doubt, FIG. 2 is intended to illustrate features of a photonic chip according to various embodiments, and is not intended to limit, for instance, the shapes, sizes, orientation, number etc. of the various features. For instance, the photonic chip / substrate 202 may be of any suitable shape, such as a regular or irregular polygonal shape. In various embodiments, the photonic chip / substrate 202 may be of a square shape, rectangular shape, or any other polygonal shape with four comers. In other words, a main surface of the substrate 202 / photonic chip may be of a regular or irregular polygonal shape, with examples being of a square shape (as shown in FIG. 2), a rectangular shape or any other polygonal shape with four comers. However, in various other embodiments, a main surface of the substrate 202 / photonic chip may be, for instance, an irregular polygonal shape with any suitable number of corners, e.g., 3, 4, or 5.

[0020] Various embodiments may achieve a greater field of view (FOV). The outputs of the OP As, e.g., OP As 204a, 204b, may have an off-axis arrangement for increasing the FOV. The OPA 204a may face a first direction, while the OPA 204b may face a second direction different from the first direction. Tn various embodiments, the photonic chip may have a field of view (FOV) greater than 180 °.

[0021] In various embodiments, the photonic circuit 204 may include an input (alternatively referred to optical phased array input or OPA input). The photonic circuit 204 may also include an input waveguide optically coupling the input to the main multi-mode interferometer 204c. The input may receive light from an external source, e.g., an optical fiber, and the received light may travel from the input to the main multi-mode interferometer 204c. The light may be of any suitable wavelength or wavelengths. For instance, the light may be infrared light, ultraviolet light, or visible light.

[0022] In various embodiments, the first optical phased array 204a may include a plurality of waveguides (also referred to as waveguide channels). The first optical phased array 204a may also include a plurality of phase shifters, each of the plurality of phase shifters configured to provide a phase shift to light traveling in a respective waveguide of the plurality of waveguides of the first optical phased array 204a. The second optical phased array 204b may include a plurality of waveguides. The second optical phased array 204b may also include a plurality of phase shifters, each of the plurality of phase shifters configured to provide a phase shift to light traveling in a respective waveguide of the plurality of waveguides of the second optical phased array. The plurality of phase shifters of the first optical phased array 204a and the plurality of phase shifters of the second optical phased array 204b may be thermo-based phase shifters or electrical-based phase shifters. A thermo-based phase shifter may include a heater made of a material such as metal or doped silicon. When a current is passed through the heater, the heater generates heat, thereby increasing a temperature of the respective waveguide in thermal contact with the thermo-based phase shifter, and changing a refractive index of the respective waveguide to introduce a phase shift to light traveling in the respective waveguide. Conversely, an electrical-based phase shifter may, for instance, include a liquid crystal or microelectromechanical systems (MEMS) structure. An electric field applied to the liquid crystal or the MEMS structure may modify a refractive index or geometry of the respective waveguide, thereby introducing a phase shift to light traveling in the respective waveguide.

[0023] The light emitted by the output of the first optical phased array 204a and / or the output of the second optical phased array 204b may be phase-shifted light, e g , phase-shifted infrared light. The waveguides of the first optical phased array 204a and / or the second optical phased array 204b may include any suitable material, such as silicon, germanium, silicon nitride, aluminum oxide, titanium oxide, gallium arsenide, indium phosphide polymers, or lithium niobate.

[0024] In various embodiments, the first optical phased array 204a may include one or more multi-mode interferometers configured to split or separate the one portion of light received by the first optical phased array 204a into smaller portions for transmission through the plurality of waveguides of the first optical phased array 204a. Similarly, the second optical phased array 204b may include one or more multi-mode interferometers configured to split or separate the other portion of light received by the second optical phased array 204b into smaller portions for transmission through the plurality of waveguides of the second optical phased array 204b.

[0025] In various embodiments, the first edge region and the second edge region may be adjoining edge regions of the photonic chip. An angle between the adjoining edge regions may be less than, more than or equal to 90°.

[0026] In various embodiments, the photonic circuit 204 may include more than two optical phased arrays as mentioned above. In various embodiments, the photonic circuit 204 may include one or more additional optical phased arrays having outputs at the first edge region of the photonic chip and / or the second edge region of the photonic chip. For instance, the photonic circuit 204 may include a third optical phased array having an output at the first edge region of the photonic chip, and a fourth optical phased array having an output at the second edge region of the photonic chip. Each of the additional optical phased arrays may also be optically coupled to the main multi-mode interferometer 204c, and may receive a portion of light split or separated by the main multi-mode interferometer 204c Each of the additional optical phased arrays may include a plurality of waveguides. Each of the additional optical phased arrays may also include a plurality of phase shifters, each of the plurality of phase shifters configured to provide a phase shift to light traveling in a respective waveguide of the plurality of waveguides of the additional optical phased array. Each of the additional optical phased arrays may include one or more multi-mode interferometers configured to split or separate the portion of light received by the additional optical phased array into smaller portions for transmission through the plurality of waveguides of the additional optical phased array.

[0027] The one or more photodetector arrays 206 may be arranged on any edge region or side of the photonic chip. Each photodetector array (of the one or more photodetector arrays 206) may include any number of photodetectors. In various embodiments, the one or more photodetector arrays 206 may include a first photodetector array arranged along the first edge region of the photonic chip and a second photodetector array arranged along the second edge region of the photonic chip.

[0028] The substrate 202 may include any suitable material, such as silicon, germanium, glass, or silicon oxide.

[0029] FIG. 3 shows a general illustration of a method of forming a photonic chip according to various embodiments. The method may include, in 302, forming a photonic circuit over a substrate The photonic circuit may include a first optical phased array having an output at a first edge region of the photonic chip. The photonic circuit may also include a second optical phased array having an output at a second edge region of the photonic chip different from the first edge region. The photonic circuit may further include a main multi-mode interferometer optically coupled to the first optical phased array and the second optical phased array. The photonic circuit may additionally include one or more photodetector arrays configured to detect light reflected by an object upon light from the output of the first optical phased array or the output of the second optical phased array incident onto the object.

[0030] The photonic chip may be formed by forming a photonic circuit over a substrate. The various components of the photonic circuit, e g., waveguides and phase shifters, may be formed by fabrication techniques such as deposition, lithography and / or etching.

[0031] In various embodiments, the photonic circuit may include an input. The photonic circuit may also include an input waveguide optically coupling the input to the main multimode interferometer. The input may receive light from an external source, e.g., an optical fiber, and the received light may travel from the input to the main multi-mode interferometer The main multi-mode interferometer may be configured to split or separate the light received by the main multi-mode interferometer into different portions. One portion of light may travel to the first optical phased array and another portion of light may travel to the second optical phased array.

[0032] In various embodiments, the first optical phased array may include a plurality of waveguides. The first optical phased array may also include a plurality of phase shifters, each of the plurality of phase shifters configured to provide a phase shift to light traveling in arespective waveguide of the plurality of waveguides of the first optical phased array. The second optical phased array may include a plurality of waveguides The second optical phased array may also include a plurality of phase shifters, each of the plurality of phase shifters configured to provide a phase shift to light traveling in a respective waveguide of the plurality of waveguides of the second optical phased array. The plurality of phase shifters of the first optical phased array and the plurality of phase shifters of the second optical phased array may be thermo-based phase shifters or electrical-based phase shifters.

[0033] In various embodiments, the first optical phased array may include one or more multi-mode interferometers configured to split or separate the one portion of light received by the first optical phased array into smaller portions for transmission through the plurality of waveguides of the first optical phased array. Similarly, the second optical phased array may include one or more multi-mode interferometers configured to split or separate the other portion of light received by the second optical phased array into smaller portions for transmission through the plurality of waveguides of the second optical phased array.

[0034] In various embodiments, the first edge region and the second edge region may be adjoining edge regions of the photonic chip. An angle between the adjoining edge regions may be less than, more than or equal to 90°.

[0035] In various embodiments, the photonic chip may be of a regular or irregular polygonal shape. For instance, the photonic chip may be of a square shape, rectangular shape, or any other polygonal shape with four corners. In various embodiments, the photonic chip may be of an irregular polygonal shape with any suitable number of corners.

[0036] In various embodiments, the photonic circuit may include one or more additional optical phased arrays. In various embodiments, the photonic circuit may include one or more additional optical phased arrays having outputs at the first edge region of the photonic chip or the second edge region of the photonic chip. For instance, the photonic circuit may include a third optical phased array having an output at the first edge region of the photonic chip, and a fourth optical phased array having an output at the second edge region of the photonic chip.

[0037] In various embodiments, the one or more photodetector arrays may be arranged on any edge region or side of the photonic chip. Each photodetector array (of the one or more photodetector arrays) may include any number of photodetectors. In various embodiments, the one or more photodetector arrays may include a first photodetector array arranged along thefirst edge region of the photonic chip and a second photodetector array arranged along the second edge region of the photonic chip.

[0038] In various embodiments, the photonic chip may have a field of view greater than 180°

[0039] Finite-difference time-domain (FDTD) simulation is performed to determine the steering angle of a single optical phased array (OP A). The following simulation parameters are used: 1550 nm infrared light, 16 waveguide channel s / emitter array, emitter dimension 0.7 pm x 0.4 pm (corresponds to 0.7 pm x 0.4 pm edge-coupling output taper), distance between adjacent emitters 0.2 pm. FIGS. 4A - B illustrate the beam steering when A<[> changes from 0° to 180°. FIG. 4A shows a plot of y-position (in micrometers or pm) as a function of x-position (in micrometers or pm) illustrating the two-dimensional (2D) electric field (E-field) of the emitter array including 16 emitters when A<[> = 0° according to various embodiments. FIG. 4B shows a plot of y-position (in micrometers or pm) as a function of x-position (in micrometers or pm) illustrating the two-dimensional (2D) electric field (E-field) of the emitter array including 16 emitters when A<|) = 180° according to various embodiments. To better compute the steering angle, the electric field (E-field) distributions of A<|) = 0°, 90°, and 180° at 160 pm height are plotted in FIG. 4C. FIG. 4C shows a plot of electric field (E-field, in kilo-volts or keV) as a function of x-position (in micrometers or pm) illustrating the one-dimensional (ID) electric field at 160 pm height above the array of 16 emitters when A<|> = 0, ° 90°, and 180° according to various embodiments.

[0040] FIG. 5A shows a photonic circuit 504 of a photonic chip according to various embodiments. The photonic circuit 504 may include an OPA input. FIG. 5B shows a portion (a) of the photonic circuit 504 as illustrated in FIG. 5A according to various embodiments. Fiber-to-chip coupling may be performed to couple infrared light into the photonic circuit 504 via the OPA input. The photonic circuit 504 may include a main waveguide 508 optically coupling the OPA input to the main MMI 504c. The infrared light may then be split 50 / 50 by the main MMI 504c into two separated OPAs 504a, 504b. FIG. 5C shows a portion (b) of the photonic circuit 504 as illustrated in FIG. 5A including the optical phased array (OPA) 504a according to various embodiments. OPA 504b may be similar in terms of structure to OPA 504a. In each OPA 504a, 504b, infrared light may be split into several waveguides 510 (also referred to as waveguide channels) using MMIs 512. The photonic circuit 504 may include an intervening waveguide 514a coupling the main MMI 504c to OPA 504a, 504b. The opticalphased array 504a, 504b may include one or more stages of MMIs 512 to split the infrared light. The optical phased array 504a, 504b may also include branching waveguides 514b optically coupling the MMI(s) 512 of a preceding stage to the MMI(s) 512 of a subsequent stage. The waveguides 510 may be optically coupled to the MMIs 512 of the last stage (of the one or more stages of MMIs 512). As shown in FIG. 5C, each OPA 504a, 504b may also include a plurality of phase shifters 516, each of the plurality of phase shifters 516 configured to provide a phase shift to the infrared light traveling in a respective waveguide of the plurality of waveguides 510. The phase shifters 516 may be placed on top of the waveguides 510, and may be thermal-based or electrical-based phase shifters. The optical phased array 504a, 504b may further include output waveguides 518 optical coupling the light to an output (referred to as OPA output) of the optical phased array 504a, 504b The OPA output may be an output taper exposed at an edge of the photonic chip, i.e., an edge-coupling output taper. To avoid clutter, only a few of the waveguides 510, MMIs 512, branching waveguides 514b, phase shifters 516 and output waveguides 518 are labelled in FIG. 5C. The phase-shifted infrared lights from different waveguides 510 may be re-united and emitted into free-space via the side-coupling tapers (i.e., OPA outputs), as illustrated in FIGS. 5A and 5D. FIG. 5D shows a portion (c) of the photonic circuit 504 as illustrated in FIG. 5A including the optical phased array (OPA) outputs and photodetector (PD) arrays 506 according to various embodiments. To avoid clutter, only a few of the output waveguides 518 are labelled in FIG. 5D. Photodetector (PD) arrays 506 may be placed at the edge of the photonic chip to detect the reflected phase-shifted infrared light from the object, to determine the size, shape, and distance of the object. FIG. 5E shows a cross-sectional schematic of the photonics chip according to various embodiments. The photonics circuit 504 may be formed over a substrate 502, which may be a silicon (Si) wafer. The photonics circuit 504 may be embedded in a cladding 520, which may be a silicon oxide (SiCh) layer as shown in FIG. 5E, i.e., the cladding 520 may include silicon oxide. In various other embodiments, the cladding 520 may include any other suitable material, such as silicon nitride, aluminum oxide, any suitable polymer, air or vacuum.

[0041] As shown in FIGS. 5A and 5D, OPA outputs can be conveniently placed at the adjacent sides of the photonic chip. As the maximum steering angle is 55°, as simulated in FIGS. 4A - C, placing two OPA outputs (alternatively referred to as OPA outlets) at right angles to each other (adjacent sides of the photonic chip) can result in a wide FOV of 210°. However, such an arrangement may have a blind spot. FIG. 5F shows the operation principle of thephotonic chip according to various embodiments. Objects positioned between point B to point D in FIG 5F cannot be detected by the photonic chip. However, the length of the blind spot can be reduced, e.g., to less than 100 pm, by reducing the distance between the OPA outputs. For instance, the OPA outputs may be arranged at a distance of less than 20 pm, e g., less than 10 pm from a comer defined by the adjoining first edge region and the second edge region. At the same time, the PD arrays 506 may be placed at the edge of the photonic chip (with exposed detection region) for the detection of reflected infrared light.

[0042] In various embodiments, the photonic circuit 504 may include a first OPA 504a and a second OPA 504b. Each of the first OPA 504a and the second OPA 504b may include a plurality of waveguides 510, and a plurality of phase shifters 516, each of the plurality of phase shifters 516 configured to provide a phase shift to light traveling in a respective waveguide of the plurality of waveguides 510. The photonic circuit 504 may include a main multi-mode interferometer 504c optically coupled to the first OPA 504a and the second OPA 504b. The phase shifters 516 may be configured to phase-shift the light received from the main multimode interferometer 504c. The phase-shifted light of the waveguides 510 of the first OPA 504a may be emitted at an output (i.e., OPA output) arranged at one edge of the photonics circuit 504, and the phase-shifted light of the waveguides 510 of the second OPA 504b may be emitted at an output (i .e , OPA output) arranged at an adjacent edge of the photonics circuit 504. The photonics circuit 504 may include a plurality of photodetector arrays 506 arranged along the edges having the OPA outputs.

[0043] In various embodiments, the field-of-view (FOV) of the photonic chip may be widened by including more OP As in the photonic circuit of the photonic chip. FIG. 6 shows (a) a photonic circuit including a first optical phased array (OPA) and a second optical phased array (OPA) according to various embodiments; and (b) a photonic circuit including a first optical phased array (OPA), a second optical phased array (OPA), a third optical phased array (OPA) and a fourth optical phased array (OPA) according to various embodiments. The output of the first OPA and the output of the third OPA may be exposed at a first edge (i.e., first edge region) of the photonic chip, while the output of the second OPA and the output of the fourth OPA may be exposed at a second edge (i.e., second edge region) of the photonic chip. The second edge may be adjoining or adjacent to the first edge.

[0044] In various embodiments, an angle between the two adjoining edges or edge regions (i.e. ABC) may be 90°, as shown in FIGS 5A, 5D and 5F. In various other embodiments, anangle between the two adjoining edges or edge regions may be at any other suitable angle. The photonic chip may be deep-etched into various shapes with various ABC to cater for different FOVs and steering angles. FIG. 7 shows (a) a photonic chip with an angle between adjoining edges or edge regions of more than 90 degrees according to various embodiments; (b) a photonic chip with an angle between adjoining edges or edge regions equal to 90 degrees according to various embodiments; and (c) a photonic chip with an angle between adjoining edges or edge regions of less than 90 degrees according to various embodiments.

[0045] In various embodiments, the photonic chip may be of a regular or irregular polygonal shape. The photonic chip may have any suitable number of corners, e.g., 3, 4, or 5 etc.

[0046] In various embodiments, the photonic chip may include two or more OPAs. The output of the OPAs may be at any side of the photonic chip. A side of the photonic chip may have any suitable number of OPA outputs The outputs of the OPAs may have an off-axis arrangement for increasing FOV. A side of the photonic chip may have more than one OPA. The PD array(s) may be at any side of the photonic chip. Each PD array may include any number of photodetectors (PDs).

[0047] In various embodiments, the photonic chip or photonic circuit may have off-axis, edge-coupled OPAs and edge-exposed PDs. The multiple, off-axis OPAs may allow the photonic chip or photonic circuit to achieve a FOV of more than 180°. The placement of the PDs at the edge of the photonic chip with exposed detection regions may allow detection of the size, shape and / or distance of the object.

Claims

Claims1 . A photonic chip comprising: a substrate; and a photonic circuit over the substrate, the photonic circuit comprising: a first optical phased array having an output at a first edge region of the photonic chip; a second optical phased array having an output at a second edge region of the photonic chip different from the first edge region; a main multi-mode interferometer optically coupled to the first optical phased array and the second optical phased array, and one or more photodetector arrays configured to detect light reflected by an object upon light from the output of the first optical phased array or the output of the second optical phased array incident onto the object.

2. The photonic chip according to claim 1, wherein the first optical phased array comprises: a plurality of waveguides; and a plurality of phase shifters, each of the plurality of phase shifters configured to provide a phase shift to light traveling in a respective waveguide of the plurality of waveguides of the first optical phased array; and wherein the second optical phased array comprises: a plurality of waveguides; and a plurality of phase shifters, each of the plurality of phase shifters configured to provide a phase shift to light traveling in a respective waveguide of the plurality of waveguides of the second optical phased array.

3. The photonic chip according to claim 2,wherein the plurality of phase shifters of the first optical phased array and the plurality of phase shifters of the second optical phased array are thermo-based phase shifters or electrical-based phase shifters.

4. The photonic chip according to any one of claims 1 to 3, wherein the first edge region and the second edge region are adjoining edge regions of the photonic chip.

5. The photonic chip according to claim 4, wherein an angle between the adjoining edge regions is less than, more than or equal to 90°.

6. The photonic chip according to any one of claims 1 to 5, wherein the photonic chip is of a regular or irregular polygonal shape.

7. The photonic chip according to claim 6, wherein the photonic chip is of a square shape, rectangular shape, or any other polygonal shape with four corners.

8. The photonic chip according to any one of claims 1 to 7, wherein the photonic circuit comprises one or more additional optical phased arrays having outputs at the first edge region of the photonic chip or the second edge region of the photonic chip.

9. The photonic chip according to any one of claims 1 to 8, wherein the one or more photodetector arrays comprise: a first photodetector array arranged along the first edge region of the photonic chip; and a second photodetector array arranged along the second edge region of the photonic chip.

10. The photonic chip according to any one of claims 1 to 9,wherein the photonic chip has a field of view greater than 180°.

11. A method of forming a photonic chip, the method comprising: forming a photonic circuit over a substrate, the photonic circuit comprising: a first optical phased array having an output at a first edge region of the photonic chip; a second optical phased array having an output at a second edge region of the photonic chip different from the first edge region; a main multi-mode interferometer optically coupled to the first optical phased array and the second optical phased array; and one or more photodetector arrays configured to detect light reflected by an object upon light from the output of the first optical phased array or the output of the second optical phased array incident onto the object.

12. The method according to claim 11, wherein the first optical phased array comprises: a plurality of waveguides; and a plurality of phase shifters, each of the plurality of phase shifters configured to provide a phase shift to light traveling in a respective waveguide of the plurality of waveguides of the first optical phased array; and wherein the second optical phased array comprises: a plurality of waveguides; and a plurality of phase shifters, each of the plurality of phase shifters configured to provide a phase shift to light traveling in a respective waveguide of the plurality of waveguides of the second optical phased array.

13. The method according to claim 12, wherein the plurality of phase shifters of the first optical phased array and the plurality of phase shifters of the second optical phased array are thermo-based phase shifters or electrical-based phase shifters.

14. The method according to any one of claims 11 to 13, wherein the first edge region and the second edge region are adjoining edge regions of the photonic chip.

15. The method according to claim 14, wherein an angle between the adjoining edge regions is less than, more than or equal to 90°.

16. The method according to any one of claims 11 to 15, wherein the photonic chip is of a regular or irregular polygonal shape.

17. The method according to claim 16, wherein the photonic chip is of a square shape, rectangular shape, or any other polygonal shape with four corners.

18. The method according to any one of claims 11 to 17, wherein the photonic circuit further comprises one or more additional optical phased arrays having outputs at the first edge region of the photonic chip or the second edge region of the photonic chip.

19. The method according to any one of claims 11 to 18, wherein the one or more photodetector arrays comprise: a first photodetector array arranged along the first edge region of the photonic chip; and a second photodetector array arranged along the second edge region of the photonic chip.

20. The method according to any one of claims 11 to 19, wherein the photonic chip has a field of view greater than 180°

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