Optical phased array with linearly scalable phase shifter for 2D beam steering

Abstract

An optical phased array for 2D steering of an optical beam includes optical waveguides, each waveguide having a plurality of scatterers, a first segment of the optical waveguide configured to steer the optical beam in an x-direction, the first segment including a first optical phase shifter, and a second segment of the optical waveguide configured to steer the optical beam in a direction different from the first segment, the second segment including a second optical phase shifter.

Description

[Technical Field]

[0001] The present invention relates to beam steering of light, and more particularly to an optical phased array that manipulates light beams of different dimensions and directions using an optical field of a fixed optical wavelength. [Background technology]

[0002] Recent advances in silicon photonics have led to the development of nanophotonic optical phased arrays (OPAs). OPA antennas are photonic components capable of changing the direction of a emitted beam lobe in real time. This ability to dynamically and precisely shift the direction of an emitted beam is useful in applications such as light detection and ranging (LiDAR) systems and free-space transceivers for directing beams carrying information signals towards specific objects and / or receivers.

[0003] Beam steering from optical photodynamic devices (OPAs) has traditionally utilized photonic components incorporating movable mirrors controlled by hydraulic pumps and micro-electromechanical systems. As a result of efforts to further miniaturize, beam steering components have been developed that are modulated based on the structural properties of materials such as liquid crystals, ferroelectrics, and phase-change materials, or based on optical properties such as refractive index and wavelength.

[0004] Among various beam steering techniques, modulation based on optical properties is particularly well-suited for on-chip beam steering. This can be achieved by shifting the optical phase difference of the optical field at the beam emitter by inducing a refractive index shift in the optical waveguide within the OPA and a shift in the optical wavelength of the optical field sent to the optical waveguide within the OPA, respectively, using an optical phase shifter and a tunable light source. To enable two-dimensional (2D) beam steering, it is customary to manipulate the optical beam using an optical phase shifter in one dimension and a tunable light source in the other. However, using optical wavelength shifts for beam steering presents the following problems: i. It is not common to have a lasing gain medium that allows for large shifts in optical wavelength. ii. In LiDAR systems, the properties of the detected object and the distance may vary with wavelength. iii. In free-space transceivers, using optical wavelength for beam steering makes it impossible to use a unique optical wavelength for different data streams. iv. It may be difficult to find other photonic components (such as waveguides or photodetectors) within a beam steering system that can accommodate a wide wavelength range similar to that of the beam steering platform. v. Continuously adjusting the optical power of the light field emitted from the beam steering platform to compensate for variations in ambient solar irradiance in free space at different wavelengths (the light field from the platform must compete with it) can be complex. Therefore, it is important to have a system that allows for the manipulation of light beams in different directions and dimensions using a light field of a fixed wavelength.

[0005] 2D beam steering using purely optical phase shifters can be achieved with conventional beam steering platforms for beam steering using a fixed optical wavelength, but the number of optical phase shifters typically increases and decreases non-linearly with the number of emitters in the array row. As a result, the following problems arise. i. It can take time to manage the beam steering system. ii. Due to the large number of optical phase shifters required, the platform occupies a large footprint. iii. Due to the large number of optical phase shifters, the beam steering platform becomes energy inefficient.

Summary of the Invention

Problems to be Solved by the Invention

[0006] To provide an improved photonic component that enables the manipulation of optical beams in different directions and dimensions using a fixed optical wavelength of an optical field (coherent light) via an optical phase shifter, where it is desirable for the number of optical phase shifters to increase and decrease linearly with the number of rows of the OPA array.

Means for Solving the Problems

[0007] According to a first aspect, an optical phased array for 2D operation of an optical beam comprises an optical waveguide, and each waveguide has a plurality of scatterers. A first segment of the optical waveguide is configured to operate the optical beam in the x direction, and the first segment comprises a first optical phase shifter. A second segment of the optical waveguide is configured to operate the optical beam in a direction different from the first segment (e.g., in the y direction), and the second segment comprises a second optical phase shifter.

[0008] From the foregoing disclosure and the following detailed description of various embodiments, it will become apparent to those skilled in the art that the present invention brings about a significant advancement in the technology of OPA. Particularly important in this regard is the potential that the present invention brings to provide 2D beam steering to OPA using optical phase shifters that linearly increase and decrease with the number of rows of the OPA array. Further features and advantages of the various embodiments will be better understood in light of the detailed description provided below.

Brief Description of the Drawings

[0009] [Figure 1] It is a schematic diagram for explaining the use of an optical phase shifter for manipulating an optical beam in two directions or dimensions (2D) using a fixed optical wavelength by modulating the optical phase of the optical field in a waveguide along the rows and columns of an OPA according to a specific embodiment disclosed herein.

[0010] [Figure 2] It is a schematic diagram for explaining the use of an optical phase shifter for modulating the optical phase of the optical field in a waveguide along the columns of an OPA according to a specific embodiment disclosed herein.

[0011] [Figure 3] It is a schematic diagram for explaining the use of an optical phase shifter for modulating the optical phase of the optical field in a waveguide along the rows of an OPA according to a specific embodiment disclosed herein.

[0012] [Figure 4] In the last column, it is a schematic diagram for explaining the use of an optical phase shifter for modulating the optical phase of the optical field in a waveguide along the rows of an OPA according to a specific embodiment disclosed herein.

[0013] [Figure 5] It is a schematic diagram for explaining the use of an optical phase shifter for modulating the optical phase of the out-of-plane scattered optical field φmn scattered by a scatterer disposed in column n of an OPA according to a specific embodiment disclosed herein, thereby modulating the directivity θx of the scattered optical beam in the x-axis at row m.

[0014] [Figure 6] This is a schematic diagram illustrating the use of an optical phase shifter to modulate the optical phase of an out-of-plane scattered optical field φm1 by a scatterer positioned in row m of an optical phased array, thereby modulating the directionality θy of the out-of-plane scattered optical beam in the y-axis at column n=1, according to a particular embodiment disclosed herein.

[0015] [Figure 7] This table shows schematic diagrams illustrating the use of a metallic thermo-optical phase shifter for manipulating a light beam in both the x and y dimensions, according to specific embodiments disclosed herein.

[0016] [Figure 8] This table shows schematic diagrams illustrating the use of a highly doped semiconductor thermo-optic heater for manipulating a light beam in the x-dimensional and an optical phase shifter in the form of a pn junction plasma dispersion effect-based modulator for manipulating a light beam in the y-dimensional, both using a fixed optical wavelength.

[0017] [Figure 9] This table shows partial isometric schematic diagrams of optical phase shifters (a phase shifter based on the plasma dispersion effect of a pn junction, a highly doped semiconductor thermo-optic phase shifter, and a metallic thermo-optic phase shifter, as shown in four examples of the model in Figure 9) according to some preferred embodiments disclosed herein.

[0018] [Figure 10] This figure shows a simulation plot of the exemplary doping effect of the resulting phase shift Δφ and attenuation, with respect to a voltage applied to a 6 mm long pn-doped optical phase shifter according to one embodiment of the OPA disclosed herein.

[0019] [Figure 11]This table shows the estimated z-components of the electric field obtained according to some embodiments of the photonic component disclosed herein, at different refractive indices of the waveguide forming part of the OPA, where the refractive index can be modulated using a phase shifter placed in or otherwise integrated with the waveguide of the OPA.

[0020] [Figure 12] This table compares polar coordinate plots of far-field intensity obtained with different optical phase differences Δφy (i.e., phase difference Δφ in the y-direction) of the optical field sent into the waveguide, which can be modulated using a phase shifter placed in or otherwise integrated into the waveguide of the OPA. [Modes for carrying out the invention]

[0021] It should be understood that the accompanying drawings are not necessarily to a fixed scale and present somewhat simplified representations of various features illustrating the fundamental principles of the present invention. Specific design features of the OPA disclosed herein, including, for example, the specific dimensions of the scatterer / emitter, are in part determined by the specific intended application and operating environment. Certain features of the illustrated embodiments are enlarged or modified from others to aid in clearer understanding. In particular, thin features may be thickened, for example, for clarity of illustration. Unless otherwise specified, all references of dimensions, directions, and positions are based on the orientation shown in the drawings.

[0022] Those skilled in the art, i.e., those with knowledge or experience of the art in this field, will see that the optical phased arrays disclosed herein are subject to numerous uses and design modifications. The following detailed description of various alternative features and embodiments illustrates the general principles of the invention with reference to an optical phase assembly for 2D beam steering that uses a phase shifter that increases or decreases linearly with the number of rows in the optical phase array. This is in contrast to conventional OPAs for 2D beam steering operated using a fixed optical wavelength, which use an optical phase shifter that increases or decreases non-linearly with the number of rows in the OPA array. The OPAs disclosed herein may be used as beam steering systems that can form part of a LiDAR system or a free-space transceiver, and may be used, for example, as both a transmitter and a receiver. In view of the interests of this disclosure, other embodiments suitable for other applications will be apparent to those skilled in the art.

[0023] Figure 1 shows a schematic diagram of an optical phased array (OPA) 100 illustrating the use of an optical phase shifter to achieve 2D beam steering using an optical field of a fixed optical wavelength by modulating the optical phase of an optical field in a series of waveguides along rows (M) and columns (N) of the OPA according to a particular embodiment disclosed herein. The OPA comprises an array of operationally connected photonic components formed in rows and columns, the array comprising a first segment 117 of an optical phase shifter located substantially adjacent to (below, above, on one side, or on the other side of) the waveguides 100 and scatterers 121 (which may constitute a series of rows and columns of the array) or otherwise integrated with (or embedded with) them, and a second segment 118 of an optical phase shifter located adjacent to or otherwise integrated with waveguides 119 (which may include another series of rows and columns of the array) operationally connected to the first segment. The first segment enables manipulation of the light beam in the x-dimensional and comprises at least one first optical phase shifter 122 (forming an array 117), the optical phase shifter 122 is positioned substantially adjacent to, or otherwise integrated with, at least one (M≧1) waveguide 110 and a plurality of (N)120 optical nanostructures (also referred to as scatterers or emitters) 121 arranged at periodic points 112 in the segment along each waveguide. The second segment enables manipulation of the light beam in a dimension different from the x-dimensional, typically the y-dimensional (i.e., 90° azimuthal from the x-dimensional), and comprises at least one second optical phase shifter 123 (forming an array 118), the optical phase shifter 123 is positioned adjacent to, or otherwise integrated with, at least one waveguide 119 operationally connected to the waveguide 110 of the first segment. Each phase shifter 122 forming part of array 117 modulates the optical phase of the optical field within optical waveguide 110, and each phase shifter 123 forming part of array 118 modulates the optical phase of the optical field in optical waveguide 119 connected to optical waveguide 110. The OPA can be scaled up to have any number of optical waveguides and scatterers M × N. Each m of the M optical waveguides 119 is configured to receive the optical field propagating to m of the M optical waveguides 110. The subscripts m and n represent the rows and columns of the array, respectively.In a preferred embodiment, each row may be equipped with the same type of optical phase shifter, and the second segment may have only one row of optical phase shifters. Optionally, each optical phase shifter may be formed as a different layer (a first layer corresponding to the first optical phase shifter and a second layer corresponding to the second optical phase shifter, with the first layer adjacent to each corresponding waveguide and the second layer adjacent to each corresponding waveguide). The first optical phase shifter may also contain a different material than the second optical phase shifter. Both the first and second optical phase shifters may be located adjacent to or integrated with the corresponding waveguides.

[0024] Advantageously, such photonic components of this OPA can be fully mounted on a chip using standard manufacturing techniques such as lithography and vapor deposition, and standard photonic materials including, but not limited to, silicon (Si), silicon nitride (Si3N4), germanium (Ge), lithium niobate (Li3NbO3), barium titanate (BaTiO3), and indium phosphide (InP). Optionally, the wavelength of the input light field may be, for example, the short-wavelength infrared region of the electromagnetic spectrum from 1.4 μm to 1.7 μm. Depending on the application of the photonic component, visible wavelengths (0.38 μm to 0.75 μm) and near-infrared wavelengths (0.75 μm to 1.4 μm) may also be used. One or more electrical connections may be provided between the first optical phase shifter of the first segment and the second optical phase shifter of the second segment. Furthermore, in the LiDAR system, the controller may be configured to cooperate with an array (117 and 118) of optical phase shifters (122 and 123) positioned adjacent to or otherwise integrated with at least one waveguide (110 and 119) and a scatterer 121 to receive the radiated light field reflected from the object, and may also incorporate a processor for calculating information about the surface properties of the object based on the reflected light received by the scatterer and waveguide.

[0025] Waveguides (110 and 119) may be circular or rectangular (rib or ridge) waveguides having an elongated top surface and side walls extending from the top surface. The refractive index of the waveguide core may be higher than that of the surrounding waveguide cladding. The waveguide cladding may comprise a lower cladding and an upper cladding. Waveguides can include several different types of waveguides. For example, waveguides may be total internal reflection-based waveguides (which constitute the vast majority of optical waveguides conventionally used in integrated photonics), slot waveguides, and surface plasmon-polariton waveguides. Alternatively, in-plane scattering waveguides may be used, such as waveguides formed from photonic crystals (which also utilize total internal reflection) and metamaterials. The composition of each of the waveguides may be at least one of, for example, Si, SiO2, BaTiO3, Li3NbO3, InP, III-V compounds, II-VI compounds, and polymers. Each of the plurality of waveguides may be doped with p-type or n-type material. The waveguides can correspond to any optical waveguide mode, such as the transverse electric mode and the transverse magnetic mode. The scatterer / emitter 121 may be either a Mie scatterer or a Rayleigh scatterer. More specifically, Mie scattering refers primarily to the scattering of an optical field from a scatterer whose diameter, width, or diagonal is usually close to the wavelength of the incident optical field, whereas in Rayleigh scattering, the diameter, width, or diagonal of the scatterer is at most one-tenth of the wavelength of the incident optical field. The composition of each of the plurality of scatterers may be at least one of, for example, Si, SiO2, BaTiO3, Li3NbO3, InP, III-V compounds, II-VI compounds, and polymers. Each of the plurality of scatterers may be doped with a positively charged dopant (p-type material) or a negatively charged dopant (n-type material). Positively charged dopants include, for example, boron, gallium, and aluminum, while negatively charged dopants include, for example, arsenic, phosphorus, and antimony. Each of the multiple scatterers can be embedded in the corresponding waveguide, and / or each of the multiple scatterers may be in contact with the upper or side wall of the corresponding waveguide.

[0026] Figure 2 shows a schematic diagram of a row (N) of an OPA of row m according to one embodiment of the present invention. Each row includes an optical phase shifter 122 that shifts the optical phase of the optical field in the waveguide 110, perturbed by a plurality of 120 scatterers 121. Waveguide 110 is operationally connected to waveguide 119 in which the optical phase shifters 122 (forming an array 117) are located / or otherwise integrated. The scatterers are located at periodic points 112, generally adjacent to waveguide 110. Each scatterer 121 perturbs a portion (α and φ) of the optical field from the waveguide. in,m (where α represents the amplitude and phase of the optical field, respectively) are evanescently coupled (at rate α) and out-of-plane scattered (at rate γ) 140. Each m of the M optical waveguides 119 is an approximation of a plane wave a iφ in,m It is configured to receive an optical field of wavelength λo which can be expressed using α and φ in,m These represent the amplitude and phase of the optical field sent to each waveguide, respectively. The subscripts m and n here again represent the row and column of the array, respectively.

[0027] Figure 3 shows a schematic diagram similar to Figure 2, but shows the first (n=1) row of the OPA according to one embodiment of the present invention. Each row comprises an array 118 of optical phase shifters 123 that shift the optical phase of the optical field in a waveguide 119 connected to a waveguide 110, which is perturbed by a plurality of 120 scatterers 121. Each scatterer 121 perturbs a portion (α and φ) of the optical field from the waveguide. in,m The 130 and 140 (where m and n represent the amplitude and phase of the light field, respectively) are evanescently coupled (at rate α) and out-of-plane scattered (at rate γ). The subscripts m and n here again represent the rows and columns of the array, respectively.

[0028] Figure 4 shows a schematic diagram similar to Figure 3, but showing the last (n=N) row of the OPA. Each row comprises an array 118 of optical phase shifters 123 that shift the optical phase of the optical field in a waveguide 119 connected to a waveguide 110, which is perturbed by a plurality of 120 scatterers 121, and according to one embodiment, here again as a result a portion (α and φ) of the optical field from the waveguide 110. in,m(representing the amplitude and phase of the optical field respectively) are evanescently coupled by the scatterer 121 at a rate α and scattered out of the plane at a rate γ. The subscripts m and n here also represent the row and column of the array respectively.

[0029] FIG. 5 summarizes the beam steering function of the first segment according to an embodiment, shifting the optical phase of the optical field in the waveguide 110 via the optical phase shifter 122 (α and φ in,m representing the amplitude and phase of the optical field respectively), evanescently coupling at a rate α by the scatterer 121 arranged in the n-th column of the OPA and scattering out of the plane at a rate γ, so as to modulate the directivity θ of the scattered light beam in the x-axis at the m-th row x A schematic diagram showing the use of an optical phase shifter for modulation is shown. The subscripts m and n represent the row and column of the array respectively. λ eff,fs 、Δφ x 、and d x are the effective wavelength of the optical field in free space, the optical phase difference (in the x direction) of the optical field in the scatterer, and the scatterer pitch (in the x direction) respectively. α' is the approximate amplitude of the optical field scattered out of the plane from each scatterer.

[0030] The beam directivity (or beam steering angle) θ of the OPA, which is a function of the emitter pitch d, i.e., the distance 124 between the centers of adjacent scatterers functioning as emitters, can be designed based on the following equation.

Equation

[0031] Figure 6 summarizes the beam steering function of the second segment according to one embodiment, and shows a schematic diagram similar to that of Figure 5, but shifts the optical phase of the optical field (α and φ) in the waveguide 119 connected to the waveguide 110 via the array 118 of optical phase shifters 123. in,m (where θ represents the amplitude and phase of the light field, respectively), the scatterers 121 arranged in row n of the OPA evanescently couple 130 and scatter out of plane 140, thereby determining the directionality θ of the scattered light beam in the y-axis at row n=1. y This shows the use of an optical phase shifter for modulation. The subscripts m and n represent the rows and columns of the array, respectively. λ eff,fs , Δφ y , and d y These are the effective wavelength of the light field in free space, the optical phase difference of the light field at the scatterer (y-direction), and the scatterer pitch (y-direction), respectively. α' is the approximate amplitude of the light field scattered out of the plane from each scatterer.

[0032] The optical phase of the optical field in the waveguide 110 of the first segment 117 and the second segment 118 (determining the directionality of the beam in the x-direction / dimension and y-direction / dimension, respectively) can be varied by changing the refractive index of the waveguide in the array. Both the first and second optical phase shifters may include phase shifters based on thermo-optic effects, plasma dispersion effects, electro-optic effects (such as the Pockels effect), perturbations of the evanescent field tuned by micro-electromechanical means (changing the effective refractive index of the OPA waveguide), or structural changes in the material (such as liquid crystal, ferroelectric, and phase-change materials). Thermo-optic phase shifters may include metal heaters, alloy heaters, ceramic heaters, and highly doped semiconductor heaters; doped phase shifters based on plasma dispersion effects may include pn-doped or pin-doped semiconductors; phase shifters based on electro-optic effects may include modulators based on the Pockels effect, such as Li3NbO3 and BaTiO3, or modulators based on the Kerr effect; photonic micro-electromechanical system switching phase shifters may include micro-electromechanical system switches that change the effective refractive index of an optical phased array waveguide by causing perturbations in the evanescent field; and phase shifters based on structural changes in materials may include liquid crystals, ferroelectrics, or phase-change materials. Phase shifters that change the refractive index of a waveguide within an OPA may be the same as or different from each other as required for a particular intended function, and the first phase shifter may be the same as or different from the second phase shifter. Changes in refractive index can be advantageously induced, for example, by electrically heating the waveguide (via thermo-optic effects), electrically changing the spatial carrier concentration in the doped semiconductor waveguide (changing the refractive index and adsorption of the phase shifter via plasma dispersion effects), and electrically changing the birefringence of the waveguide (via electro-optic effects).Changes in heat, spatial carrier concentration, and optical birefringence within the waveguide may be induced by applying a voltage to a thermo-optic phase shifter (a ceramic / alloy phase shifter such as metal or indium tin oxide, or a highly doped semiconductor heater near the waveguide using a doped / ion-implanted semiconductor region extending along the waveguide (hereinafter referred to as a doped semiconductor phase shifter)), and by applying a voltage to an electro-optic phase shifter (formed using a material with a high electro-optic coefficient, such as one exhibiting the Pockels effect). Metal heaters are not limited to these but may be constructed using materials with a high thermo-optic coefficient, including titanium nitride (TiN) and nickel-chromium (NiCr). Doped semiconductor heaters may include semiconductor materials highly doped with positively charged (p++) or negatively charged (n++) dopants. The doping concentration of the highly doped heater region is approximately 10 for n++ heaters. 20 cm -3 N a With a p++ heater, approximately 10 20 cm -3 N d This may be the case. Alternatively, a phase shifter based on the plasma dispersion effect may include either a pn-doped semiconductor or a pin-doped semiconductor. The doping concentration in the plasma dispersion effect-based doped semiconductor region is approximately 10 in the n-doped region. 17 ~10 18 cm -3 N a In the p-doped region, approximately 10 17 ~10 18 cm -3 N d This may be the case. Waveguide doping that enables spatial carrier concentration changes within the waveguide may be formed using a pn junction or a pin junction. A pn ​​junction is a junction in which a region of positively charged dopant is injected into the waveguide (p-doped region) adjacent to a region of negatively charged dopant (n-doped region), and a pin junction is a junction in which a p-doped region is adjacent to an undoped region (or "intrinsic" region) adjacent to an n-doped region. Phase shifters based on the electro-optic effect may be constructed using materials with high electro-optic coefficients, such as Li3NbO3 and BaTiO3.

[0033] Figure 7 is a schematic top view of one embodiment of the OPA 110 corresponding to Figure 1, the OPA having a photonic component 117 for manipulating the light beam in the x-direction (by an optical phase shift applied to the waveguide of the first segment) and a photonic component 118 for manipulating the light beam in the y-direction (by an optical phase shift applied to the waveguide of the second segment 119). The photonic component 117 is shown together with one embodiment of a thermo-optic phase shifter 154 (an example of an optical phase shifter 122) which includes a titanium nitride (TiN) thermo-optic heater 134 (on a substrate 141) for modulating the optical phase of the light field in the waveguide 110 that is perturbed by a plurality of scatterers 121 arranged along the waveguide. The waveguide cladding may include a lower cladding 114 and an upper cladding 113. The heater heats the waveguide of the first segment, thereby modulating the refractive index of the waveguide of the first segment to shift the optical phase difference of the beam-emitter optical field in the x-direction, which then manipulates the optical beam along the x-direction. The photonic component 118 is shown together with one embodiment of a thermo-optic phase shifter 153 (an example of an optical phase shifter 123), which also includes a titanium nitride (TiN) thermo-optic heater 134 (on substrate 141) for modulating the optical phase of the optical field in the waveguide of the first segment connected to the waveguide 110 of the second segment. The heater heats the waveguide of the second segment, thereby modulating the refractive index of the waveguide of the second segment to shift the optical phase difference of the beam-emitter optical field in the y-direction, which then manipulates the optical beam along the y-direction. Each thermo-optic heater 134 may be connected to a metal structure (bottom layer) electrically connected to another metal structure (top layer) via an electrical via. Advantageously, heating of a thermo-optic heater can be achieved by applying a voltage to an electrical pad electrically connected to a metal structure.

[0034] Figure 8 is a schematic top view of another embodiment of the OPA corresponding to that in Figure 1, where the OPA also has, in one embodiment, a photonic component 117 for manipulating the light beam in the x-direction (by an optical phase shift applied to the waveguide 110 of the first segment) and a photonic component 118 for manipulating the light beam in the y-direction (by an optical phase shift applied to the waveguide 119 of the second segment). The photonic component 117 modulates the optical phase of the light field in the waveguide 110, which is perturbed by a plurality of scatterers 121 arranged along the waveguide, with n++ (e.g., acceptor concentration Na = 1 × 10⁻¹⁶). 20 cm 3 The optical phase shifter 122 is shown with a doped (ion-implanted) thermo-optic heater 137 (highly doped). The waveguide cladding may comprise a lower cladding 114 and an upper cladding 113. The heater heats the waveguide 110 of the first segment, thereby modulating the refractive index of the waveguide 110 of the first segment to shift the optical phase difference of the beam-emitter optical field in the x-direction, which then manipulates the optical beam along the x-direction. The photonic component 118 is shown with an optical phase shifter 123 comprising a pn junction (a p-doped region, indicated by 135, and an n-doped region, indicated by 136) on the waveguide 119 for modulating the optical phase of the optical field in the waveguide 119. A voltage applied across the pn junction forming the optical phase shifter 122 induces a plasma dispersion effect in the second segment waveguide 119, thereby modulating the refractive index of waveguide 119 and shifting the optical phase difference of the beam-emitter optical field in the y-direction, which then manipulates the optical beam along the y-direction. The doped semiconductor structures 135, 136, and 137 may be connected to a metal structure (bottom layer) electrically connected to another metal structure (top layer) via electrical vias. Advantageously, the plasma dispersion effect can be induced from the doped semiconductor waveguide structures 135 and 136 by applying a voltage to an electrical pad electrically connected to the metal structure. Similarly, heating of the thermo-optic heater can be induced from the highly doped semiconductor structure 137 by applying a voltage to an electrical pad electrically connected to the metal structure.

[0035] The phase shifter 122 does not need to extend along the entire length of the waveguide 110 of the first segment, and the phase shifter 123 does not need to extend along the entire length of the waveguide 119 of the second segment. The required optical phase shift may be modified by creating different optical phase shift regions for each segment by varying the portion of the segment over which the phase shifter extends.

[0036] Figure 9 is a table showing partial isometric schematic diagrams of different optical phase shifters (a highly doped semiconductor thermo-optic phase shifter 152 in the first segment, a pn-doped semiconductor phase shifter 151 in the second segment, and metallic thermo-optic phase shifters (154 and 153, respectively) in the first and second segments, corresponding to the optical phase shifters shown in Figures 7 and 8, in four examples of the model in Figure 9). For example, according to one embodiment of the OPA, the OPA 100 may comprise a row (M) of metallic thermo-optic phase shifters 154 located in the first segment, adjacent to or otherwise integrated with a waveguide 119 based on total internal reflection formed from Si3N4, and another row (M) of metallic thermo-optic phase shifters 153 located in the second segment, adjacent to or otherwise integrated with a waveguide 110 and a scatterer 121 based on total internal reflection formed from Si3N4. According to another embodiment of the OPA, the OPA 100 may comprise a first row (M) of a first segment pn-doped optical phase shifter 152 and another second row (M) of a second segment doped semiconductor thermo-optical phase shifter 151. Optionally, the number of rows (M) and columns (N) of the OPA 100 may range from, for example, 2 to 10,000. The OPA 100 may comprise optical phase shifters (117 and 118), which may comprise any of several different types of optical phase shifters (metallic thermo-optical phase shifter, pn-doped optical phase shifter, PIN-doped optical phase shifter, doped semiconductor thermo-optical phase shifter, or optical phase shifter based on thermo-optical effects) configured for use in, for example, a LiDAR system or a free-space transceiver.

[0037] The optical phase shift induced by an optical phase shifter for beam steering varies depending on the design parameters. In the case of a thermo-optic phase shifter, the optical phase shift depends on the temperature coefficient dn / dT of the waveguide material and the length L of the waveguide region being heated. The induced optical phase shift depends on the increase in waveguide temperature ΔT and the effective wavelength λ of the optical field within the waveguide. eff,wg It can be conveniently expressed as a function of .

number

[0038] Figure 11 shows different waveguide refractive indices n wg The electric field (E) of the embodiment of the photonic component at d=0.78 μm along the xz cross section, as revealed in the five examples of the model in Figure 11: 3.48, 3.75, 4.0, 4.25, and 4.5. ZThis table shows the numerically simulated results of the z component of the profile in the finite-difference time-domain (FDTD). From Equation 1, in particular, θ in the x direction (or θ x (The direction is specified by a subscript) When Δφ=0, that is, d=λ eff,wg When (where λ eff,wg =λ0 / n eff,wg This is the effective wavelength of the optical field within the waveguide (λ in the case of this invention). eff,wg =0.78μm), and n eff,wg λ is the effective refractive index of the waveguide medium. Therefore, it can be determined that the scattered (radiated) light field propagates in free space in a direction precisely perpendicular to the waveguide structure. eff,wg Varying / d and / or Δφ shifts the beam directionality away from the direction perpendicular to the vertical (in the z-axis). For example, according to one embodiment using a wavelength of 1.55 μm as the optical field, the scatterer formed from Si may have a diameter of about 160 nm, and the waveguide may correspond to a transverse magneto-optical waveguide mode with a width of 0.7 μm and a sidewall thickness or height of 0.22 μm, partially etched with an upper cladding of air and a lower cladding of SiO2 at a slab height of 90 nm. Advantageously, in one embodiment, one optical phase shifter 122 can be placed in or otherwise integrated with each waveguide 110 that is perturbed by a plurality of emitters / scatterers 121 to enable simultaneous optical phase shift across the entire row of scatterers for beam steering in the x-direction.

[0039] Figure 12 shows different Δφ y (In the six examples of the model in Figure 12, 150°, 90°, 30°, -30°, -90°, and -150°) Different optical phase differences Δφ of the input optical field fed into the waveguide can be modulated using a phase shifter placed in or otherwise integrated into the waveguide of the OPA disclosed herein. yThis is a table comparing polar coordinate plots of the obtained far-field intensity with respect to the azimuth and zenith viewing angle in the optical phase Δφ in the y-direction. According to one embodiment using a wavelength of 1.55 μm as the optical field, each row of the waveguide is spaced 0.9 μm apart, the scatterers formed from Si have a diameter of about 160 nm, and the waveguide can correspond to transverse magneto-optical waveguide modes with a width of 0.7 μm and a sidewall thickness or height of 0.22 μm, partially etched with an upper cladding of air and a lower cladding of SiO2 at a slab height of 90 nm. In one embodiment, one optical phase shifter 123 can be placed in each waveguide connected to the waveguide 110 for beam steering in the y-direction, or otherwise integrated. Advantageously, when this configuration is combined with another configuration that uses one other optical phase shifter 122 located in or otherwise integrated with each waveguide 110 that is perturbed by multiple emitters / scatterers 121 for beam steering in the x-direction, the total number of optical phase shifters for 2D beam steering increases or decreases linearly (i.e., the total number of optical phase shifters is linearly proportional to the number of rows in the OPA array. For example, if there are 5 rows in the optical phase array, the total number of phase shifters could be 2 × 5 = 10 phase shifters (minimum number of phase shifters), 3 × 5 = 15 phase shifters, or 4 × 5 = 20 phase shifters, etc.).

[0040] From the above disclosure and the detailed description of the particular embodiments, it will be apparent that various modifications, additions, and other alternative embodiments are possible without departing from the true scope and spirit of the invention. The embodiments described are selected and described to provide the best description of the principles of the invention and its practical applications, thereby enabling those skilled in the art to use the invention by making various modifications in various embodiments to suit the particular use intended. All such modifications and variations are within the scope of the invention as determined by the claims, if the appended claims are interpreted in accordance with the fair, lawful, and justly entitled scope of the invention.

Claims

1. An optical phased array for 2D steering of an optical beam, An optical waveguide having a refractive index, wherein each waveguide has a plurality of scatterers, A first segment in the first optical waveguide of the at least one optical waveguide, wherein the first segment is configured to manipulate the light beam in the x direction, and the first segment comprises at least one first optical phase shifter positioned below or above the first optical waveguide and the plurality of scatterers, A second segment in the second optical waveguide of the at least one optical waveguide, wherein the second segment is configured to manipulate the optical beam in a direction different from that of the first segment, and the second segment comprises at least one second optical phase shifter located below or above the second optical waveguide, A waveguide cladding surrounding the first optical waveguide and the second optical waveguide, comprising a waveguide cladding including a lower cladding and an upper cladding, Combine and prepare The first optical waveguide and the second optical waveguide are connected, The first optical waveguide, the second optical waveguide, and the plurality of scatterers are arranged within the upper cladding. Optical phased array.

2. The optical phased array according to claim 1, wherein the at least one first optical phase shifter is different from the at least one second optical phase shifter.

3. The optical phased array according to claim 1, further comprising at least one electrical connection between the at least one first optical phase shifter of the first segment and the at least one second optical phase shifter of the second segment.

4. The optical phased array according to claim 1, wherein each of the at least one first optical phase shifter and the at least one second optical phase shifter changes the refractive index of the at least one optical waveguide based on one of the following: thermo-optical effects, plasma dispersion effects, electro-optical effects, photonic micro-electromechanical system switching, or structural changes of the material.

5. A thermo-optic phase shifter comprising one of a metal heater, an alloy heater, a ceramic heater, and a highly doped semiconductor heater. A phase shifter doped based on the plasma dispersion effect, comprising one of a pn-doped semiconductor and a pin-doped semiconductor, The electro-optic effect-based device comprises one of the modulators based on the Pockels effect and the modulator based on the Kerr effect, A photonic micro-electromechanical system switching phase shifter comprising a micro-electromechanical system switch that causes fluctuations in the perturbation of the evanescent field to change the refractive index of the waveguide, A phase shifter comprising one of liquid crystal, ferroelectric, and phase change material, based on a structural change of the said material, The optical phased array according to claim 4, comprising any one of the following.

6. The optical phased array according to claim 1, comprising a first row of a first segment and a second row of a second segment, wherein the at least one first optical phase shifter of each first segment is operationally connected to the at least one second optical phase shifter of the second segment.

7. The at least one optical waveguide includes a plurality of waveguides, the at least one first optical phase shifter includes a plurality of first optical phase shifters, and the at least one second optical phase shifter includes a plurality of second optical phase shifters. The optical phased array according to claim 1, wherein each first optical phase shifter comprises a first layer disposed below or above each of the corresponding waveguides, and each second optical phase shifter comprises a second layer disposed below or above each of the corresponding waveguides.

8. Each of the at least one optical waveguide and the corresponding scattering body is Si, SiO ２ Si ３ N ４ , BaTiO ３ Li ３ NboO ３ The photophased array according to claim 1, comprising independently at least one or more of InP, a polymer, a III-V compound other than InP, and a II-VI compound.

9. The optical phased array according to claim 1, wherein each of the at least one optical waveguide and the corresponding scatterer is independently doped with a p-type material or an n-type material.

10. The optical phased array according to claim 1, wherein each of the plurality of scatterers includes one of a Mie scatterer and a Rayleigh scatterer.

11. The optical phased array according to claim 1, wherein each of the plurality of scatterers is embedded in a corresponding optical waveguide.

12. The optical phased array according to claim 1, wherein each of the plurality of scatterers is in contact with the upper wall or side wall of the corresponding at least one optical waveguide.

13. The optical phased array according to claim 1, wherein each of the at least one optical waveguides is one of a waveguide based on total internal reflection and an in-plane scattering waveguide.

14. The optical phased array according to claim 1, wherein each of the at least one optical waveguides is a rectangular waveguide having an elongated top surface and side walls extending from the top surface.

15. The optical phased array according to claim 1, further comprising a controller configured to calculate information about an object based on the aforementioned light beam.

16. The optical phased array according to claim 1, having a certain number of rows, wherein the number of optical phase shifters is linearly proportional to the number of rows.

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