CN210690981U - Adjustable optical phase array - Google Patents
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- CN210690981U CN210690981U CN201921652998.8U CN201921652998U CN210690981U CN 210690981 U CN210690981 U CN 210690981U CN 201921652998 U CN201921652998 U CN 201921652998U CN 210690981 U CN210690981 U CN 210690981U
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Abstract
The application relates to the technical field of beam steering and provides an adjustable optical phased array, the adjustable optical phased array includes: the device comprises a substrate layer, a distributed Bragg reflector, a supporting layer, a piezoelectric layer, an antenna array and a transducer module for converting a phase control signal and a surface wave into each other; the antenna array and the distributed Bragg reflector are adopted to form a Fabry-Perot resonant cavity, a phase control signal output by a signal source is converted into a surface wave through a transducer module, and the surface wave is conducted to the antenna array through a piezoelectric layer, so that the Fabry-Perot resonant cavity generates corresponding oscillation, the emergent phase of the antenna array is adjusted, and the purpose of controlling a light beam is achieved.
Description
Technical Field
The application relates to the technical field of beam manipulation, in particular to an adjustable optical phase array.
Background
Beam steering (Beam steering) is a core device in the fields of laser radar, optical communication and the like, a Beam is generally steered by using modes such as a mechanical shock mirror, a Micro Electro Mechanical System (MEMS) micro mirror, a biprism, a photoelectric crystal, a liquid crystal and the like in a traditional Beam steering design scheme, however, the Beam steering speed is slow, the control elasticity is small, and the stability and reliability are poor due to the adoption of a mechanical or micro-mechanical MEMS, the biprism has the problems of uncontrollable and irregular scanning area during Beam steering, the photoelectric crystal has the problems of small Beam scanning angle, large crystal volume, high price and large driving power consumption during Beam steering, and although a spatial light modulator based on the liquid crystal is mature, the problems of slow speed, complex driving mode and weak high and low temperature resistance of a liquid crystal material exist.
With the gradual migration of professional fields such as aerospace, survey and drawing to consumption and industrial field by laser radar, traditional beam control device and beam scanning mode can't satisfy trades such as car, robot, automation to performance index's such as volume, consumption, reliability, stability, life's requirement, a neotype beam control device and beam scanning mode are urgently awaited.
SUMMERY OF THE UTILITY MODEL
The application aims to provide an adjustable optical phase array, and aims to solve the problems that in the prior art, the speed of light beam control is low, the control flexibility is small, and the stability and the reliability are poor.
In order to solve the above technical problem, an embodiment of the present application provides a tunable optical phased array, including: the device comprises a substrate layer, a distributed Bragg reflector, a supporting layer, a piezoelectric layer, an antenna array and a transducer module for converting a phase control signal and a surface wave into each other;
the distributed Bragg reflector is arranged on the surface of the substrate layer, the supporting layer is arranged between the piezoelectric layer and the distributed Bragg reflector, the antenna array and the transducer module are arranged on the surface of the piezoelectric layer, and a Fabry-Perot resonant cavity is formed between the antenna array and the distributed Bragg reflector.
Optionally, the transducer module includes one or more groups of interdigital transducers, and each group of interdigital transducers includes at least one input interdigital transducer for converting a phase control signal into a surface wave.
Optionally, every group the interdigital transducer include with input interdigital transducer sets up relatively, is used for converting surface wave into feedback signal's output interdigital transducer, antenna array locates input interdigital transducer with between the output interdigital transducer.
Optionally, the structure of the interdigital transducer is at least one of a chirp structure, a tilt structure and an apodization structure.
Optionally, the antenna array includes a plurality of nano-antenna elements, and the refractive index of the nano-antenna elements is greater than 1.9.
Optionally, the shape of the nano antenna element is at least one of a cylinder, a square, a cross, a round hole, a square hole, a cross hole, and a V shape.
Optionally, the material of the nano antenna element is any one of silicon, gallium arsenide, aluminum gallium arsenic, silicon nitride, and indium phosphide.
Optionally, the material of the antenna array is the same as the material of the piezoelectric layer.
Optionally, the piezoelectric layer is supported by a support layer to form a suspended piezoelectric film, wherein the suspension height is less than 15 um.
Optionally, the supporting layer includes a plurality of supporting structures, and a spacing between adjacent supporting structures is greater than an antenna period.
In an adjustable optical phased array provided in an embodiment of the present application, the adjustable optical phased array includes: the device comprises a substrate layer, a distributed Bragg reflector, a supporting layer, a piezoelectric layer, an antenna array and a transducer module for converting a phase control signal and a surface wave into each other; the antenna array and the distributed Bragg reflector are adopted to form a Fabry-Perot resonant cavity, a phase control signal output by a signal source is converted into a surface wave through a transducer module, and the surface wave is conducted to the antenna array through a piezoelectric layer, so that the Fabry-Perot resonant cavity generates corresponding oscillation, the emergent phase of the antenna array is adjusted, and the purpose of controlling a light beam is achieved.
Drawings
FIG. 1 is a graph of wavelength, optical path length, amplitude and phase provided by an embodiment of the present application;
FIG. 2 is a schematic diagram of a tunable optical phased array according to an embodiment of the present application;
FIG. 3 is a top view of a tunable optical phased array provided by an embodiment of the present application;
FIGS. 4a, 4b and 4c are schematic structural diagrams of various interdigital transducers provided by embodiments of the present application;
fig. 5a and 5b are schematic structural diagrams of piezoelectric layers and antenna arrays made of the same material according to embodiments of the present disclosure.
FIG. 6 is a top view of a tunable optical phased array provided in accordance with another embodiment of the present application;
FIG. 7 is a schematic diagram of a tunable optical phased array structure provided by another embodiment of the present application;
FIG. 8 is a schematic diagram of a tunable optical phased array structure provided by another embodiment of the present application;
FIG. 9 is a top view of a tunable optical phased array structure provided in accordance with another embodiment of the present application;
FIG. 10 is a schematic diagram of an interdigital transducer array layout, provided by one embodiment of the present application;
fig. 11 is a schematic diagram of a phase array in which surface acoustic waves of a sawtooth waveform propagate at an angle of 20 degrees with respect to the horizontal direction in an antenna array region according to an embodiment of the present application;
fig. 12 is a far-field distribution diagram of a light spot when a surface acoustic wave provided by an embodiment of the present application propagates in an antenna array region at an angle of 20 degrees from the horizontal direction;
fig. 13 is a schematic diagram of a phase array in which surface acoustic waves with sine wave waveforms propagate at an angle of 45 degrees with the horizontal direction in an antenna array area according to an embodiment of the present application;
fig. 14 is a light spot far-field distribution diagram of a surface acoustic wave with a sine wave waveform propagated at an angle of 45 degrees with the horizontal direction in an antenna array area according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In the description of the present application, it is to be understood that the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
In order to achieve efficient beam deflection control, the embodiments of the present application provide 0-2 π phase delay control using an optical antenna. The beam control is achieved by directly impinging light on the antenna array and then adjusting the phase response of each antenna element. Specifically, the embodiment of the application adopts the surface acoustic wave to control the response amplitude and the phase of the antenna array, and specifically, converts an electric signal into the surface acoustic wave through the input interdigital transducer. On the other hand, in the embodiment of the present application, a Fabry-Perot (FP) resonant cavity is formed between the antenna array and the distributed bragg reflector, which can greatly reduce the driving power of the surface acoustic wave and enhance the phase delay amount. The amplitude and phase of an Asymmetric FP cavity (Asymmetric FP cavity) at a resonance position along with the wavelength or the change curve of the optical path in the cavity are shown in fig. 1, and under the premise of considering the loss of the cavity material, the higher the Q value of the cavity is, the larger the slope of the phase change is, and vice versa. Therefore, by adjusting the optical path within the cavity, a phase adjustment range of 0-2 pi can be obtained, and the higher the resonance Q value, the smaller the optical path range that needs to be adjusted.
Fig. 2 is a schematic structural diagram of a tunable optical phased array based on surface acoustic wave modulation according to an embodiment of the present application, and referring to fig. 2, the tunable optical phased array in this embodiment includes: a substrate layer 10, a distributed bragg reflector 20, a support layer 30, a piezoelectric layer 40, an antenna array 60, and a transducer module 50 for interconverting a phase control signal with a surface wave; the distributed bragg reflector 20 is arranged on the surface of the substrate layer 10, the support layer 30 is arranged between the piezoelectric layer 40 and the distributed bragg reflector 20, the antenna array 60 and the transducer module 50 are arranged on the surface of the piezoelectric layer 40, and a fabry-perot resonant cavity is formed between the antenna array 60 and the distributed bragg reflector 20.
In the present embodiment, the transducer module 50 converts the input phase control signal into a surface wave by using the inverse piezoelectric effect, and the surface wave propagates along the surface of the piezoelectric layer 40 at this time because the transducer module 50 is located on the surface of the piezoelectric layer 40. In the present embodiment, the surface wave belongs to a mechanical wave, and since the piezoelectric layer 40 is formed of a piezoelectric material supporting excitation and propagation of the surface wave, when the surface wave passes through the antenna array 60, the phase delay of the fabry-perot resonator formed between the antenna array 60 and the distributed bragg reflector 20 is modulated, so as to perform delay adjustment on the emergent phase of the antenna array 60, and at this time, the incident beam directly impinges on the antenna array 60, so that the emergent phase of the antenna array 60 can be adjusted by providing a phase control signal through a signal source, and a purpose of beam control is achieved.
In one embodiment, the transducer module 50 is configured to perform a mutual conversion between a phase control signal and a surface wave, for example, the phase control signal may be an electrical signal, the transducer module 50 converts the electrical signal into a corresponding surface wave, and a user may adjust the magnitude, the frequency, and a fluctuation curve of the electrical signal to generate the corresponding surface wave to drive the antenna array 60 to generate a corresponding motion, so as to adjust the fabry-perot resonator, thereby achieving the purpose of adjusting the output phase of the adjustable optical phased array.
Further, the phase control signal may also be a laser signal, and at this time, the transducer module 50 converts the laser signal into a corresponding surface wave to drive the antenna array 60 to generate a corresponding motion, so as to adjust the fabry-perot resonant cavity, thereby achieving the purpose of adjusting the output phase of the adjustable optical phase array.
In one embodiment, the surface wave is a mechanical wave propagating along an interface between different media, and the antenna array 60 is simply resonant under the action of the surface wave, thereby tuning the fabry-perot resonator.
Further, in one embodiment, the surface wave may be a surface acoustic wave.
In one embodiment, the transducer module 50 includes one or more sets of interdigital transducers, each set including at least one input interdigital transducer for converting an electrical signal to surface acoustic waves.
In one embodiment, each set of the interdigital transducers further comprises an output interdigital transducer which is arranged opposite to the input interdigital transducer and used for converting surface acoustic waves into electric signals, and the antenna array 60 is arranged between the input interdigital transducer and the output interdigital transducer.
In the present embodiment, the input interdigital transducer in the transducer module 50 converts the input electrical signal into the surface acoustic wave by using the inverse piezoelectric effect, and since the input interdigital transducer is located on the surface of the piezoelectric layer 40, the surface acoustic wave propagates along the surface of the piezoelectric layer 40, and finally the output interdigital transducer at the other end converts the surface acoustic wave into the electrical signal for output. In this embodiment, the surface acoustic wave belongs to an acoustic signal, and since the piezoelectric layer 40 is formed of a piezoelectric material that supports excitation and propagation of the surface acoustic wave, when the surface acoustic wave passes through the antenna array 60, the phase delay of the fabry-perot resonator formed between the antenna array 60 and the distributed bragg reflector 20 is modulated, so that the outgoing phase of the antenna array 60 is adjusted in a delayed manner, at this time, incident light is directly irradiated on the antenna array 60, and the outgoing phase of the antenna array 60 is adjusted by converting an electrical signal provided by a signal source into the surface acoustic wave, thereby achieving the purpose of beam control.
In one embodiment, the transducer module 50 includes two pairs of interdigital transducers, with an included angle between the two pairs of interdigital transducers of 90 degrees.
Fig. 3 is a top view of an adjustable optical phased array according to an embodiment of the present application, and referring to fig. 3, a transducer module 50 includes an input interdigital transducer 511, an input interdigital transducer 521, an output interdigital transducer 512, and an output interdigital transducer 522, where the input interdigital transducer 511 and the output interdigital transducer 512 form a set of interdigital transducers, and the input interdigital transducer 521 and the output interdigital transducer 522 form a set of interdigital transducers.
The interdigital transducers in this embodiment are each provided on the surface of the piezoelectric layer 40 in a shape like a pattern of fingers crossing each other in both hands, see, for example, the input interdigital transducer 511 in fig. 3, the input interdigital transducer 511 being composed of a plurality of metal electrodes alternately connected to two bus bars. When the acoustic wavelength (lambda) corresponding to the frequency is equal to the period of the interdigital transducer, the excited surface acoustic wave is strongest, and the total amplitude of the surface acoustic waves excited by other frequencies is small due to phase cancellation. Therefore, the interdigital transducer has frequency selectivity, and in a specific application, the interdigital transducers with different wavelengths are designed to obtain surface acoustic wave devices with different frequencies.
In one embodiment, the structure of the interdigital transducer may be at least one of a chirp structure, a slant structure, and an apodization structure.
In this embodiment, when the interdigital transducer is a chirped structure, as shown in fig. 4c, the frequency of the signal of the interdigital transducer changes linearly with time, and the frequency changes are generated due to modulation at the front and back edges of the pulse, so that the signal spectrum is broadened, and is characterized by a chirp coefficient (which may also be referred to as a line width broadening factor).
In this embodiment, when the structure of the interdigital transducer is an inclined structure, the interdigital electrodes are periodically changed along the aperture direction of the device, as shown in fig. 4b, the upper part of the device excites a signal in a high frequency part, and the lower part of the device excites a signal in a low frequency part, so that the driving signal is divided into a plurality of sub-channels with different frequencies, each channel generates a narrow passband with different frequencies, and finally a wide passband is synthesized, thereby realizing a filter design with a wider frequency band.
In the present embodiment, when the structure of the interdigital transducer is an apodized structure, see fig. 4a, the interdigital transducer is also called an apodized chirped interdigital transducer, and the signal frequency of the interdigital transducer changes nonlinearly with time. Specifically, the refractive index of the medium dynamically changes according to the influence of the modulation of the dynamic electrical signal, so that the phase of the optical signal propagating in the medium also dynamically changes, and the change of the phase is directly reflected as the dynamic change of the frequency of the optical signal.
In the present embodiment, by setting the structure of the interdigital transducer to a chirp structure, a tilt structure, or an apodization structure, a light beam scanning range of a larger angle of view can be obtained.
Further, frequency screening of the input signal can be achieved by setting the electrode period of the interdigital transducer, so that the driving frequency is set to be at least one of single frequency, multiple frequencies and broadband frequency sweep.
In the embodiment, when the central response frequency of the interdigital transducer is 900MHz and the bandwidth is more than 300MHz, the scanning field angle of more than 10 degrees can be realized, and the scanning field angle of 60-80 degrees can be realized after passing through the 5-8 times beam expanding lens.
In one embodiment, the antenna array 60 includes a plurality of nanoantenna elements having a refractive index greater than 1.9, the plurality of nanoantenna elements being periodically arranged.
In the present embodiment, the plurality of nanoantenna elements are repeatedly arranged, and the spacing distance between adjacent nanoantenna elements is smaller than the wavelength of incident light. In a particular application, it is desirable to predetermine the wavelength range of the incident optical beam, thereby determining that the spacing of the nanoantenna elements in the tunable optical phased array is less than the wavelength of the incident optical beam.
Further, the nanoantenna elements have a size less than one-half of the wavelength of the incident light.
In an embodiment, the antenna array 60 in this embodiment is made of a high refractive material, and at this time, the antenna array 60 and the distributed bragg reflector 20 arranged opposite thereto form a sub-wavelength phase delay unit, and specifically, the phase delay amount can be adjusted by utilizing an elastic-electric effect of a surface acoustic wave generated and propagated on the piezoelectric layer 40 formed by the suspended piezoelectric material and an acoustic-optical modulation effect of the surface acoustic wave on the antenna array 60, so as to achieve the purpose of obtaining a large phase delay amount under a low power condition.
In one embodiment, the material of the nanoantenna element is any one of silicon, gallium arsenide, aluminum gallium arsenide, silicon nitride, and indium phosphide.
In one embodiment, the shape of the nanoantenna element is at least one of a cylinder, a square, a cross, a round hole, a square hole, a cross hole, a V-shape.
In this embodiment, the antenna array layer is etched by using different masks, so as to form the nano antenna elements with different shapes, and the shapes of the nano antenna elements are not limited to cylinders, squares, crosses, round holes, square holes, cross holes and V-shapes, and can be specifically set according to user requirements.
In one embodiment, referring to fig. 3, the structure of the nanoantenna element in the antenna array 60 in this embodiment is a cylinder, the center wavelength of the response of the tunable optical phased array in this embodiment may be 1550nm in the communication band, wherein the constituent material of the nanoantenna element may be any one of monocrystalline silicon, polycrystalline silicon, or amorphous silicon.
In one embodiment, the piezoelectric layer 40 is the same material as the antenna array 60.
In this embodiment, the piezoelectric layer 40 and the nano-antenna array are formed by using piezoelectric materials, so that the manufacturing process of the adjustable optical phase array structure can be simplified, as shown in fig. 5a, in this case, the nano-antenna elements located in the area of the antenna array 60 are supported by the supporting layer 30, the piezoelectric layer 40 is disposed between the antenna array 60 and the transducer module 50, and the surface wave generated by the transducer module 50 is conducted into the antenna array through the piezoelectric layer 40.
Further, as shown in fig. 5b, the antenna array 60 and the piezoelectric layer 40 in this embodiment are formed by using the same piezoelectric material, for example, the antenna array 60 and the piezoelectric layer 40 may both be made of AlGaAs with piezoelectric characteristics, as shown in fig. 6, the nano antenna elements in the antenna array 60 in this embodiment are cross-shaped structures and are formed by intersecting vertical grating structures, at this time, the antenna array may be used as a suspended piezoelectric film, which not only can play a role of exciting and propagating surface acoustic waves, but also can adjust the phase delay of the antenna array 60 based on the surface acoustic waves, so as to achieve the purpose of adjusting the phase of an incident light beam to output an outgoing light beam required by a user. In the embodiment, the antenna array and the piezoelectric layer are integrated, so that the processing complexity is greatly simplified.
In one embodiment, the piezoelectric layer 40 is supported by a support layer 30 to form a suspended piezoelectric film, wherein the suspended height is less than 15 um.
In this embodiment, the supporting layer 30 is disposed between the piezoelectric layer 40 and the dbr 20, and the surface of the piezoelectric layer 40 is provided with the antenna array 60, so that a fabry-perot resonator (F-P cavity) is formed between the antenna array 60 and the dbr 20, and when the surface acoustic wave is transmitted to the area of the antenna array 60, the fabry-perot resonator between the antenna array 60 and the dbr 20 oscillates, so as to adjust the emergent phase of the tunable optical array structure.
Furthermore, the piezoelectric layer 40 forms a piezoelectric film suspension structure through the support layer 30, and the electric elastic effect generated by the surface acoustic wave can be greatly enhanced, so that the purpose of complete 0-2 pi phase delay can be achieved under a small optical path adjustment amount.
In one embodiment, the support layer comprises a plurality of support structures, and the spacing between adjacent support structures is greater than the antenna period. In this embodiment, the antenna period is the separation distance between adjacent nanoantenna elements.
In one embodiment, the spacing between adjacent support structures is greater than 10 um.
In one embodiment, the support layer 30 may be made of silicon (Si), gallium arsenide (GaAs), or silicon dioxide (SiO)2) Any one of the above.
In one embodiment, the antenna array 60 and the piezoelectric layer 40 may be made of AlGaAs, which has piezoelectric properties, and the supporting layer 30 is made of gallium arsenide (GaAs), so as to facilitate selective etching with AlGaAs during the fabrication process.
Fig. 7 is a schematic diagram of a tunable optical phased array structure according to another embodiment of the present application, and referring to fig. 7, in order to improve the electromechanical coupling efficiency of AlGaAs material, a layer of piezoelectric material with a higher electromechanical coupling coefficient, such as lithium niobate, zinc oxide, aluminum nitride, etc., is formed on an antenna array 60 made of AlGaAs material for energy interconversion.
Further, with the array structure in this embodiment, the same mask as the AlGaAs layer can be used for etching in the region of the antenna array 60, so that higher electromechanical coupling efficiency can be obtained without increasing the process complexity.
In one embodiment, the thickness of the piezoelectric layer 40 is greater than 200 nm.
In one embodiment, the floating height of the piezoelectric layer 40 formed by the floating piezoelectric film is less than 15um, the thickness of the floating piezoelectric film is less than 1um, and the material used for the piezoelectric layer 40 is lithium niobate.
In one embodiment, the distributed bragg reflector 20 includes a plurality of alternately stacked dielectric layers, and the refractive index of any two adjacent dielectric layers is different.
In one embodiment, the dielectric layer is made of titanium oxide (TiOx), silicon dioxide (SiO)2) At least two of silicon nitride (SiNx), gallium arsenide (GaAs), and aluminum gallium arsenide (AlGaAs). For example, the DBR 20 may be TiOx/SiO2、SiNx/SiO2Or AlGaAs/GaAs dielectric layer stack due to titanium oxide (TiOx), silicon dioxide (SiO)2) When the films with different refractive indexes are stacked together alternately every week, when incident light passes through the films with different refractive indexes, the light reflected by each layer is subjected to constructive interference due to the change of a phase angle, and then is combined together to obtain reflected light with higher reflectivity.
In one embodiment, when the number of stacking periods of the dielectric layers with different refractive indexes is 12, the reflectivity of the distributed bragg reflector 20 can reach more than 99%. When the number of stacking periods reaches 30, the reflectivity of the distributed bragg reflector 20 may reach 99.9%. For example, when the number of stacking cycles is 12 in the case of AlGaAs/GaAs dielectric layer stack used in the dbr 20, it means that the AlGaAs/GaAs stack is twelve times, i.e., twelve layers of AlGaAs and twelve layers of GaAs are alternately stacked.
In one embodiment, the DBR 20 is formed by AlGaAs/GaAs alternating stacks 30, where the reflectivity of the tunable optical phased array can reach 99.98%.
In one embodiment, the material of the substrate layer 10 is any one of silicon, gallium arsenide, quartz, sapphire, gallium nitride, and silicon carbide.
Fig. 8 is a schematic diagram of an adjustable optical phased array structure according to another embodiment of the present application, and referring to fig. 8, in order to meet the requirements of different technology platforms, in this embodiment, the dbr 20 and the piezoelectric layer 40 are separately prepared by a wafer bonding method, and after the two parts are separately manufactured, the two layers are bonded together by a wafer bonding method. Specifically, in this embodiment, first, the dbr 20 is formed on the substrate layer 10, then the supporting layer 30 is formed on the dbr 20, on the other hand, the antenna array 60 and the transducer module 50 are formed on the surface of the piezoelectric layer 40, and finally, the two parts are bonded together to form the top view of the complete tunable optical phased array, as shown in fig. 9.
Further, in the present embodiment, when the piezoelectric layer 40 is bonded to the support layer 30, the antenna array 60 and the transducer module 50 disposed on the surface of the piezoelectric layer 40 may be located between the piezoelectric layer 40 and the dbr 20, and a fabry-perot resonator is formed between the antenna array 60 and the dbr 20.
In one embodiment, a bi-directional interdigital transducer (IDT) layout can produce a two-axis spot scan, but the spots are four spots symmetrically distributed over four quadrants. To better achieve single spot control, the design of the interdigital transducers (IDTs) can be made more flexible, thereby better achieving dual axis control of a single excident spot. In a specific application, in order to realize one light spot and simultaneously realize plane scanning along two axial directions, the propagation direction of the surface acoustic wave needs to be changed while the frequency of the surface acoustic wave is adjusted. As shown in fig. 10, through the arrangement of the interdigital transducers, a voltage-controlled variable capacitor or a radio frequency vector modulator is used between each interdigital transducer to generate a phase delay, so that the phase delay linear transformation between the interdigital transducers is realized, and the purpose of adjusting the wavefront of the surface acoustic wave is achieved. In the embodiment, through a single set of interdigital transducer array design, the dual-axis scanning control of the light spot is realized, so that the beam control of the surface acoustic wave can be realized based on an electronic circuit.
In an embodiment, the present embodiment provides a method for manufacturing a tunable optical phased array as described in any of the above embodiments, the method comprising: forming a distributed Bragg reflector on the surface of the substrate layer; forming an antenna array and a transducer module on the surface of the piezoelectric layer, wherein the transducer module is used for converting the phase control signal and the surface wave into each other; and arranging a supporting layer on the antenna array and the distributed Bragg reflector so that the antenna array and the distributed Bragg reflector form a Fabry-Perot resonant cavity.
In the present embodiment, the transducer module 50 converts the input phase control signal into a surface wave by using the inverse piezoelectric effect, and the surface wave propagates along the surface of the piezoelectric layer 40 at this time because the transducer module 50 is located on the surface of the piezoelectric layer 40. In this embodiment, the surface wave belongs to a mechanical wave, because the piezoelectric layer 40 is formed of a piezoelectric material supporting excitation and propagation of the surface wave, and the support layer 30 is disposed between the antenna array 60 and the distributed bragg reflector 20, so that the antenna array 60 and the distributed bragg reflector 20 form an adjustable fabry-perot resonator, when the surface wave passes through the antenna array 60, a phase delay of the fabry-perot resonator formed between the antenna array 60 and the distributed bragg reflector 20 is modulated, thereby performing a delay adjustment on an outgoing phase of the antenna array 60, at this time, an incident beam is directly incident on the antenna array 60, and therefore, the outgoing phase of the antenna array 60 can be adjusted by providing a phase control signal through a signal source, and a beam control purpose is achieved.
Fig. 11 is a schematic diagram of a phase array in which a saw-tooth waveform surface acoustic wave propagates in an antenna array region at an angle of 20 degrees with respect to a horizontal direction, fig. 12 is a far-field distribution diagram of a spot when the surface acoustic wave propagates in the antenna array region at an angle of 20 degrees with respect to the horizontal direction, in this embodiment, an angle sin θ of incident light after being subjected to phase delay processing of the antenna array is m λ/d (m is an integer), where λ is a wavelength of the surface acoustic wave, d is an interval distance between adjacent phase-nanometer antenna elements in the antenna array, and when the surface acoustic wave propagates in the antenna array region at an angle of 20 degrees with respect to the horizontal direction, a far-field spot diagram of outgoing light of the surface acoustic wave is shown in.
Fig. 13 is a schematic diagram of a phase array in which a surface acoustic wave with a sine wave waveform propagates at an angle of 45 degrees with respect to the horizontal direction in an antenna array region, and referring to fig. 13, the surface acoustic wave propagates at an angle of 45 degrees with respect to the horizontal direction in a nano-antenna region, and a far-field distribution diagram of a spot generated by the surface acoustic wave is shown in fig. 14. Compared with sawtooth waves, sine waves are easier to generate, but two or more outgoing light waves are emitted, and corresponding design needs to be made corresponding to the construction of a laser radar optical system.
In one embodiment, the transducer module 50 includes one or more sets of interdigital transducers, each set including at least one input interdigital transducer for converting an electrical signal to surface acoustic waves.
In one embodiment, the drive frequency of the input interdigital transducer is at least one of a single frequency, multiple frequencies, and a broadband frequency sweep.
In one embodiment, the drive frequency of the input interdigital transducer is greater than 100 MHz.
In one embodiment, the bandwidth of the broadband frequency sweep is greater than 100 MHz.
In one embodiment, the nanoantenna elements are arranged with a period less than the wavelength of the incident light.
In one embodiment, the size of the antenna element is less than one-half of the wavelength of the incident light. For example, if the wavelength range of the incident light may be 0.1um-40um, the size of the antenna element is less than one-half of the wavelength of the incident light, and the size of the antenna element may be in the range of 0.001um-20 um.
In one embodiment, each set of the interdigital transducers further comprises an output interdigital transducer which is arranged opposite to the input interdigital transducer and used for converting surface acoustic waves into electric signals, and the antenna array 60 is arranged between the input interdigital transducer and the output interdigital transducer.
In this embodiment, the signal source provides a phase control signal, the output interdigital transducer converts the surface wave into a feedback electrical signal, the host receives the phase control signal, the driving electrical signal and the feedback electrical signal, and outputs the operating state of the adjustable optical phased array according to the feedback electrical signal and the phase control signal.
In one embodiment, the transducer module 50 includes a plurality of sets of interdigital transducers, wherein an incident interdigital transducer converts a phase control signal into a surface acoustic wave, the surface acoustic wave is transmitted to an output interdigital transducer along a piezoelectric layer, the output interdigital transducer converts the surface acoustic wave into a feedback electrical signal, the phase control signal is compared with the feedback electrical signal, and a comparison result is analyzed to determine whether the adjustable optical phase array is working normally, for example, when the piezoelectric layer in the adjustable optical phase array is damaged or not matched with a preset process parameter, the surface acoustic wave generated by the interdigital transducer at one end is transmitted to the interdigital transducer at the other end, the surface acoustic wave has a larger loss or is abnormal, and at this time, the feedback electrical signal generated by the output interdigital transducer corresponds to the received surface acoustic wave, so that by comparing the phase control signal with the feedback electrical signal, thereby judging the working state of the adjustable optical phased array.
In one embodiment, outputting the operating state of the tunable optical phased array based on the feedback electrical signal and the phase control signal comprises: acquiring a voltage difference value of the feedback electric signal and the phase control signal; and judging whether the voltage difference value is within a preset voltage threshold range, if so, judging that the working state of the adjustable optical phase array is normal, and if not, judging that the working state of the adjustable optical phase array is abnormal.
In this embodiment, the voltage difference between the feedback electrical signal and the phase control signal is obtained, and the power loss of the surface acoustic wave in the transmission process is represented by the voltage difference, and if the loss of the surface acoustic wave in the transmission process is larger, the voltage difference between the feedback electrical signal and the phase control signal is larger, further, a user may set a preset voltage threshold range as needed, and if the voltage difference is within the preset voltage threshold range, it is determined that the working state of the adjustable optical phase array is normal, and if the voltage difference is not within the preset voltage threshold range, it is determined that the working state of the adjustable optical phase array is abnormal.
In an adjustable optical phased array provided by the present application, the adjustable optical phased array includes: the device comprises a substrate layer, a distributed Bragg reflector, a supporting layer, a piezoelectric layer, an antenna array and a transducer module for converting a phase control signal and a surface wave into each other; the distributed Bragg reflector is arranged on the surface of the substrate layer, the supporting layer is arranged between the piezoelectric layer and the distributed Bragg reflector, the antenna array and the transducer module are arranged on the surface of the piezoelectric layer, a Fabry-Perot resonant cavity is formed between the antenna array and the distributed Bragg reflector, the Fabry-Perot resonant cavity is formed by adopting the antenna array and the distributed Bragg reflector, a phase control signal and a surface wave are converted mutually through the transducer module, and the surface acoustic wave is conducted to the antenna array through the piezoelectric layer, so that the corresponding oscillation is generated in the Fabry-Perot resonant cavity, the emergent phase of the antenna array is adjusted, and the purpose of controlling the light beam is achieved.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. A tunable optical phased array, comprising: the device comprises a substrate layer, a distributed Bragg reflector, a supporting layer, a piezoelectric layer, an antenna array and a transducer module for converting a phase control signal and a surface wave into each other;
the distributed Bragg reflector is arranged on the surface of the substrate layer, the supporting layer is arranged between the piezoelectric layer and the distributed Bragg reflector, the antenna array and the transducer module are arranged on the surface of the piezoelectric layer, and the antenna array and the distributed Bragg reflector form a Fabry-Perot resonant cavity.
2. The tunable optical phased array of claim 1, wherein the transducer module comprises one or more sets of interdigital transducers, each set of interdigital transducers comprising at least one input interdigital transducer for converting a phase control signal to a surface wave.
3. The tunable optical phased array of claim 2, wherein each set of said interdigital transducers comprises an output interdigital transducer disposed opposite said input interdigital transducer for converting a surface wave to a feedback signal, said antenna array being disposed between said input interdigital transducer and said output interdigital transducer.
4. The optical phased array of claim 2, wherein the structure of the interdigital transducer is at least one of a chirped structure, a tilted structure, and an apodized structure.
5. The tunable optical phased array of claim 1, wherein the antenna array comprises a plurality of nanoantenna elements, the nanoantenna elements having a refractive index greater than 1.9.
6. The tunable optical phased array of claim 5, wherein the nanoantenna elements are in the shape of at least one of a cylinder, a square, a cross, a round hole, a square hole, a cross hole, a V-shape.
7. The tunable optical phased array of claim 5, wherein the nanoantenna elements are made of any one of silicon, gallium arsenide, aluminum gallium arsenide, silicon nitride, and indium phosphide.
8. The tunable optical phased array of claim 1, wherein the antenna array is the same material as the piezoelectric layer.
9. The tunable optical phased array of claim 1, wherein the piezoelectric layer is supported by a support layer to form a suspended piezoelectric film, wherein the suspended height is less than 15 um.
10. The tunable optical phased array of claim 1, wherein the support layer comprises a plurality of support structures, adjacent support structures being spaced apart by more than an antenna period.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021056545A1 (en) * | 2019-09-29 | 2021-04-01 | 深圳力策科技有限公司 | Manufacturing method for adjustable optical phase array and adjustable optical phase array |
| CN114614250A (en) * | 2022-05-10 | 2022-06-10 | 电子科技大学 | Vortex electromagnetic wave antenna based on Fabry-Perot resonant cavity |
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2019
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021056545A1 (en) * | 2019-09-29 | 2021-04-01 | 深圳力策科技有限公司 | Manufacturing method for adjustable optical phase array and adjustable optical phase array |
| CN114614250A (en) * | 2022-05-10 | 2022-06-10 | 电子科技大学 | Vortex electromagnetic wave antenna based on Fabry-Perot resonant cavity |
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