CN110750003A - Rapid two-dimensional scanning optical waveguide phased array structure - Google Patents

Abstract

The invention discloses a rapid two-dimensional scanning optical waveguide phased array structure, which comprises a substrate layer, wherein the substrate layer is made of n-type doped GaAs material; a buffer layer arranged on the substrate layer and made of p-type doped Al_0.3Ga_0.68An As material; the microstructure layer is arranged on the buffer layer and is made of n-type doped GaAs materials, the microstructure layer comprises a coupling element, a cascading power divider unit, a phase-shifting device unit and a transmitting antenna unit, and the coupling element, the cascading power divider unit, the phase-shifting device unit and the transmitting antenna unit are sequentially connected with one another through a waveguide structure. The substrate layer and the microstructure layer of the invention both adopt GaAs materials, and the buffer layer adopts Al_0.3Ga_0.68As material, and the microstructure layer comprises coupling element, cascade power divider unit, phase-shifting device unit and transmitting antenna unit connected in sequence, and the optical waveguide phased array structure remarkably improves the scanning speed of two-dimensional optical waveguide phased array。

Description

A fast two-dimensional scanning optical waveguide phased array structure

technical field

The invention belongs to the technical field of micro-nano optical devices, in particular to a fast two-dimensional scanning optical waveguide phased array structure.

Background technique

In recent years, Optical Phased Array (OPA, Optical Phased Array), which was born out of microwave phased array technology, has gradually become a hot spot in the study of beam scanning in the world. Optical phased array technology utilizes the electro-optic, thermo-optic, acousto-optic and other characteristics of the working material to achieve electrical and non-mechanical control of beam pointing, and can be multiplexed through modules to achieve high-power, multi-beam expansion.

OPA has broad application prospects in military and civilian fields such as lidar, laser guidance, and laser display. So far, domestic and foreign researchers have carried out various researches on OPA technology, and two-dimensional scanning optical waveguide phased arrays have also been rapidly developed.

At present, most of the two-dimensional optical phased arrays are made of Si material, which uses its thermo-optic effect to realize beam scanning through the control of external circuits. However, due to the limitation of the thermo-optic response time, the scanning speed of the optical phased array of silicon material is very high. It is difficult to exceed 200KHz, and it is difficult to meet the application requirements of fast scanning.

SUMMARY OF THE INVENTION

In order to solve the above problems existing in the prior art, the present invention provides a fast two-dimensional scanning optical waveguide phased array structure. The technical problem to be solved by the present invention is realized by the following technical solutions:

A fast two-dimensional scanning optical waveguide phased array structure, comprising:

a substrate layer, the substrate layer is an n-type doped GaAs material;

a buffer layer, disposed on the substrate layer, the buffer layer is a p-type doped Al _0.3 Ga _0.68 As material;

A microstructure layer, disposed on the buffer layer, the microstructure layer is an n-type doped GaAs material, wherein the microstructure layer includes a coupling element, a cascaded power divider unit, a phase shift device unit and A transmitting antenna unit, the coupling element, the cascaded power divider unit, the phase-shifting device unit and the transmitting antenna unit are sequentially connected to each other through a waveguide structure, and the phase-shifting device unit includes several phase-shifting devices , the transmitting antenna unit includes a plurality of transmitting antennas, the cascaded power divider units are respectively connected to the phase-shifting devices, and each of the phase-shifting devices is respectively connected to one of the transmitting antennas.

In one embodiment of the present invention, the coupling element includes a first incident waveguide buffer structure, a first outgoing waveguide buffer structure, and a first incident waveguide buffer structure and a first outgoing waveguide buffer structure disposed between the first incident waveguide buffer structure and the first outgoing waveguide buffer structure. Periodic waveguide grating structure, wherein the first periodic waveguide grating structure includes grooves arranged periodically, and the set width of the first incident waveguide buffer structure gradually increases to the set width of the first exit waveguide buffer structure decrease.

In one embodiment of the present invention, the shape of the coupling element is a sector shape.

In one embodiment of the present invention, the cascaded power splitter unit includes a plurality of power splitters, each of the power splitters includes an incident waveguide, a multimode waveguide and two outgoing waveguides, and the incident waveguide and The multimode waveguides are connected through a first taper structure, and the multimode waveguides and the two outgoing waveguides are respectively connected through a second taper structure.

In an embodiment of the present invention, the phase-shifting device includes an aluminum layer, and the aluminum layer is disposed at a position where the waveguide structure needs to be powered between the cascaded power divider unit and the transmitting antenna unit superior.

In an embodiment of the present invention, the transmit antenna includes a second incident waveguide buffer structure, a second outgoing waveguide buffer structure, and a second incident waveguide buffer structure and a second outgoing waveguide buffer structure disposed between the second incident waveguide buffer structure and the second outgoing waveguide buffer structure. Periodic waveguide grating structure, wherein the second periodic waveguide grating structure includes grooves arranged periodically, and the set width of the second incident waveguide buffer structure is equal to the set width of the second exit waveguide buffer structure .

In an embodiment of the present invention, the shape of the transmitting antenna is a bar shape.

In an embodiment of the present invention, the doping concentration of the microstructure layer is 10 ¹⁸ cm ^-3 .

In an embodiment of the present invention, the doping concentration of the substrate layer is 10 ¹⁸ cm ^-3 .

In an embodiment of the present invention, the doping concentration of the buffer layer is 10 ¹⁵ cm ^-3 .

Beneficial effects of the present invention:

The substrate layer and the microstructure layer of the present invention are all made of GaAs material, the buffer layer is made of Al _0.3 Ga _0.68 As material, and the micro structure layer includes sequentially connected coupling elements, cascaded power divider units, phase shifting device units and transmitting antennas unit, this optical waveguide phased array structure significantly improves the scanning speed of the two-dimensional optical waveguide phased array.

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

Description of drawings

1 is a schematic diagram of a structure of a fast two-dimensional scanning optical waveguide phased array provided by an embodiment of the present invention;

2 is a schematic diagram of a microstructure layer provided by an embodiment of the present invention;

3 is a schematic diagram of a waveguide structure provided by an embodiment of the present invention;

4 is a schematic diagram of a simulation optimization result provided by an embodiment of the present invention;

5 is a schematic diagram of a result of a simulation experiment provided by an embodiment of the present invention;

6 is a schematic diagram of a coupling device in an XZ direction provided by an embodiment of the present invention;

7 is a schematic diagram of a coupling device in the YZ direction provided by an embodiment of the present invention;

8 is a schematic diagram of a result of another simulation experiment provided by an embodiment of the present invention;

9 is a schematic diagram of a cascaded power divider unit provided by an embodiment of the present invention;

10 is a schematic diagram of another simulation optimization result provided by an embodiment of the present invention;

11 is a schematic diagram of another simulation optimization result provided by an embodiment of the present invention;

12 is a schematic diagram of the result of another simulation experiment provided by an embodiment of the present invention;

13 is a schematic diagram of a phase shifting device provided by an embodiment of the present invention;

14 is a schematic diagram of a transmitting antenna provided by an embodiment of the present invention;

15 is a schematic diagram of another simulation optimization result provided by an embodiment of the present invention;

16 is a schematic diagram of another simulation optimization result provided by an embodiment of the present invention;

17 is a schematic diagram of a simulation result of electro-optical modulation provided by an embodiment of the present invention;

18 is a schematic diagram of a wavelength modulation simulation result provided by an embodiment of the present invention;

19 is a schematic diagram of another wavelength modulation simulation result provided by an embodiment of the present invention;

FIG. 20 is a schematic diagram of a scanning speed controlled by an electro-optical effect according to an embodiment of the present invention.

Detailed ways

The present invention will be described in further detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

Example 1

Please refer to FIG. 1 and FIG. 2 at the same time. FIG. 1 is a schematic diagram of a fast two-dimensional scanning optical waveguide phased array structure provided by an embodiment of the present invention, and FIG. 2 is a schematic diagram of a microstructure layer provided by an embodiment of the present invention. The Y direction in FIG. 1 is the thickness direction of the two-dimensional scanning optical waveguide phased array structure, the Z direction is the length direction of the two-dimensional scanning optical waveguide phased array structure, and the X direction in FIG. 2 is the two-dimensional scanning optical waveguide phased array structure. The width direction of the array structure. This embodiment provides a fast two-dimensional scanning optical waveguide phased array structure. The fast two-dimensional scanning optical waveguide phased array structure includes a substrate layer 1, a buffer layer 2 and a microstructure layer 3, wherein the substrate layer 1 is n-type Doped GaAs material, buffer layer 2 is p-type doped Al _0.3 Ga _0.68 As material, microstructure layer 3 is n-type doped GaAs material, and buffer layer 2 is arranged on substrate layer 1, microstructure layer 3 It is arranged on the buffer layer 2. In addition, the microstructure layer 3 includes a coupling element 31, a cascaded power divider unit 32, a phase-shifting device unit 33 and a transmitting antenna unit 34. The coupling element 31 and the cascaded power divider unit 32 The phase-shifting device unit 33 and the transmitting antenna unit 34 are sequentially connected to each other through the waveguide structure, and the phase-shifting device unit 33 includes several phase-shifting devices, the transmitting antenna unit 34 includes several transmitting antennas, and the cascaded power divider unit 32 is connected to the phase-shifting devices, and each phase-shifting device is respectively connected to a transmitting antenna.

The substrate layer and the microstructure layer of the present invention are all made of GaAs material, and the buffer layer is made of Al _0.3 Ga _0.68 As material. At the same time, the incident beam of the present invention exits through the end face of the optical fiber, enters the microstructure layer through the coupling device, and enters the cascaded power splitter unit through the waveguide, thereby being divided into multi-channel in-phase beams, and each channel beam enters the phase-shifting device unit through the waveguide. The phase shifter unit controls the phase of the optical field in each channel uniformly, and finally enters the transmitting antenna unit through the waveguide for transmission. This structure significantly improves the scanning speed of the two-dimensional optical waveguide phased array.

At present, planar optical waveguide phased arrays based on GaAs/GaAlAs materials have obvious advantages such as simple structure, fast response speed, large scanning range, low driving voltage, and simple circuit control, and have become a research hotspot for fast two-dimensional scanning OPA. However, so far, there are relatively few studies on two-dimensional phased arrays based on GaAs/GaAlAs materials. Therefore, in order to further improve the performance of the two-dimensional scanning optical waveguide phased array structure of this embodiment, the material used for the substrate layer 1 in this embodiment is n-type doped GaAs, and the material used for the buffer layer 2 is Al _0.3 Ga The material used for _0.68 As and the microstructure layer 3 is an n-type doped GaAs material. In addition, in order to further improve the performance of the two-dimensional scanning optical waveguide phased array structure of this embodiment, the doping concentration of the substrate layer 1 is 10 ¹⁸ cm ⁻³ , and the doping concentration of the buffer layer 2 is 10 ¹⁵ cm ⁻³ . ^3. The doping concentration of the microstructure layer 3 is 10 ¹⁸ cm ^-3 .

Based on the above parameters, this embodiment considers the single-mode condition of waveguide transmission, namely:

为单模波导厚度，

n₁为空气的折射率，n₂为微结构层的折射率，n₃为缓冲层的折射率，λ为入射波长，m为单模的阶数，本实施例的m取0。图4为波导结构的厚度、宽度对于传输效率影响的仿真结果，优选的，请参见图3，波导结构的宽度301与厚度302均为1μm，本实施例基于上述参数进行了仿真实验，其仿真结果请参见图5，根据仿真结果可知传输损耗为2.038dB/cm。in,

is the thickness of the single-mode waveguide,

n ₁ is the refractive index of air, n ₂ is the refractive index of the microstructure layer, n ₃ is the refractive index of the buffer layer, λ is the incident wavelength, m is the order of the single mode, and m in this embodiment is 0. Fig. 4 is a simulation result of the influence of the thickness and width of the waveguide structure on the transmission efficiency. Preferably, please refer to Fig. 3. The width 301 and the thickness 302 of the waveguide structure are both 1 μm. The results are shown in Figure 5. According to the simulation results, the transmission loss is 2.038dB/cm.

Referring to FIG. 6 and FIG. 7 at the same time, the coupling element 31 of this embodiment includes a first incident waveguide buffer structure 311 , a first outgoing waveguide buffer structure 313 , and a first incident waveguide buffer structure 311 and a first outgoing waveguide buffer structure 313 . between the first periodic waveguide grating structure 312 , wherein the first periodic waveguide grating structure includes periodically arranged grooves 314 , and the set width D1 of the first incident waveguide buffer structure 311 is equal to the width D1 of the first outgoing waveguide buffer structure 313 The set width D2 is gradually reduced, and preferably, the shape of the coupling element 31 is a fan shape.

Further, please refer to FIG. 7 again, the structure of the coupling element 31 is a waveguide grating coupler, wherein the first periodic waveguide grating structure 312 is formed by periodically etching grooves on the waveguide structure, and at the same time for the incident light The first incident waveguide buffer structure 311 and the first outgoing waveguide buffer structure 313 without etched groove portions are respectively retained at both ends of the first periodic waveguide grating structure 312, and the end of the first outgoing waveguide buffer structure 313 is connected to the waveguide. The structures are connected, and the light emitted from the end of the fiber is coupled into the cascaded power splitter unit 32 through the first incident waveguide buffer structure 311 , the first periodic waveguide grating structure 312 and the first outgoing waveguide buffer structure 313 in sequence. 7 is the grating period, θ is the incident angle, AC is the optical path difference of the outgoing beams from adjacent grooves, E is the width of the waveguide grating groove, and F is the depth of the waveguide grating groove.

The coupling element 31 in this embodiment is a structure based on the diffraction effect of the waveguide grating. The periodic grooves in the first periodic waveguide grating structure 312 will periodically modulate the index of refraction of the waveguide, and the light propagating along the waveguide will be coupled to the upper cladding layer (ie, the air layer), which can act as a emitting device to convert the light in the waveguide. The light is emitted into the external environment, and according to the principle of optical path reversibility, the light in the external environment can also be coupled into the waveguide.

The optical path difference of the emitted light beams from adjacent grooves in this embodiment is:

Δ=n ₁ AC-n _eff T

where n _eff is the effective refractive index.

The maximum value of beam diffraction in this embodiment will appear where the optical path difference is an integer multiple of the wavelength, that is:

(n ₁ sinθ-n _eff )T=mλ

Derive the Prague condition:

β=k ₁ sinθ- _mkg

in,

I_in为入射光的能量，I_out为出射光的能量，则入射光将有一部分耦合进入波导，还有一部分入射光会发生反射，耦合进波导的光会耦合向衬底层，或从衬底层中向波导中反射。耦合元件31的凹槽形状、深度、周期都会对η产生影响。在本实施例中n₁＝1，n₂＝3.273，n₃＝3.373，波长λ选用通讯波长1.55μm，按照本实施例的结构设计，则有效折射率n_eff＝3.368。由于光路的可逆原理，耦合元件31的优化过程类似于发射天线的逆过程，具体请参见发射天线优化原理，这里不再赘述。Therefore, only light satisfying the Bragg condition can be coupled into the grating or propagated out. The effect of the waveguide grating coupler can be reflected by the coupling efficiency η, while

I _in is the energy of the incident light, and I _out is the energy of the outgoing light, then a part of the incident light will be coupled into the waveguide, and a part of the incident light will be reflected, and the light coupled into the waveguide will be coupled to the substrate layer, or from the substrate layer Reflection in the middle of the waveguide. The shape, depth and period of the groove of the coupling element 31 all have an effect on n. In this embodiment, n ₁ =1, n ₂ =3.273, n ₃ =3.373, and the wavelength λ is selected as the communication wavelength of 1.55 μm. According to the structural design of this embodiment, the effective refractive index n _eff =3.368. Due to the reversible principle of the optical path, the optimization process of the coupling element 31 is similar to the inverse process of the transmission antenna. For details, please refer to the transmission antenna optimization principle, which will not be repeated here.

Preferably, the grating period T is 0.46 μm, the number of periods is 40, the width E of the waveguide grating groove is 0.3 μm, the depth F of the waveguide grating groove is 0.2 μm, the incident angle θ is 90°, and the entire coupling element 31 has a The length is 58 μm, the set width D1 of the first incident waveguide buffer structure 311 is 32 μm, and the set width D2 of the first exit waveguide buffer structure 313 is 1 μm. In this embodiment, a simulation experiment is carried out based on the above parameters, and the simulation result is shown in FIG. 8 . According to the simulation structure, it can be known that the coupling efficiency is 30%.

Referring to FIG. 9 , the cascaded power divider unit 32 includes a plurality of power dividers, and the power divider is a multi-mode cascaded interferometer structure, wherein each power divider includes an incident waveguide 321 , a multi-mode waveguide 323 and two The outgoing waveguides 325 , that is, the power splitter is a 1×2 power splitter, the incoming waveguide 323 and the multimode waveguide 325 are connected through the first taper structure 322 , and the multimode waveguide 323 and the two outgoing waveguides 325 are connected by a first taper structure 322 . They are respectively connected by a second taper structure 324. Both the first taper structure 322 and the second taper structure 324 are a kind of trapezoid structure, preferably both are isosceles trapezoid structures, and the short side of the first taper structure 322 is connected to the incident waveguide 323, The long side is connected to the multimode waveguide 323 , the long side of the second taper structure 324 is connected to the multimode waveguide 323 , and the short side is connected to the outgoing waveguide 325 .

The cascaded power splitter unit 32 in this embodiment mainly utilizes the self-mirror effect of the multi-mode waveguide, that is, when a light wave is incident into the multi-mode waveguide, several guided modes are excited inside the multi-mode waveguide. Interfering with each other, the direction of light wave propagation will periodically generate an image of the incident light field, and the size of the period is determined by the number of images and the position of the incident light field.

In order to better determine the performance of the two-dimensional scanning optical waveguide phased array structure, it is necessary to determine the width and propagation length of the multimode waveguide of the power splitter, and the imaging period of the self-mirror effect is defined by the following formula:

为多模波导的自镜像效应周期长度，λ为入射波长，W_e为多模波导的有效宽度，其可以由下式确定：where n _eff of this formula is the effective refractive index of the 1×2 power divider,

is the period length of the self-image effect of the multimode waveguide, _λ is the incident wavelength, and We is the effective width of the multimode waveguide, which can be determined by the following formula:

Among them, W _MMI is the physical width of the power divider, and n _clad is the refractive index of the buffer layer. The length of the power divider (MMI) can be expressed as:

Among them, p is the imaging period of the self-mirror effect, p in this embodiment is 1, N is the number of outputs, and N=2 in this embodiment.

Figures 10 and 11 show the optimization results of the insertion loss of the power splitter, that is, setting the power monitor at the end of the output waveguide 325 to test the output efficiency of the power splitter. Figure 10 shows the influence of the width of the multimode waveguide 325 on the beam splitting efficiency. Influence of mode waveguide 325 length on transmission efficiency. It is observed from the simulation results in FIGS. 10 and 11 that the optimal multimode waveguide 325 has a width of 5 degrees m and a length of 24.58 m.

处，两个出射波导对称的设置在距零点的处，第一taper结构322和第二taper结构324的长边均为1.5μm、短边均为1μm、短边至长边的距离为1μm。本实施例基于上述参数进行了仿真实验，其仿真结果请参见图12，根据仿真结构可知插入损耗为2.38dB。Preferably, the L _MMI is 24.5 μm and the W _MMI is 5.00 μm. In this embodiment, the lower side of the multimode waveguide is zero, and the incident waveguide is set at a distance from the zero

At , the two outgoing waveguides are symmetrically arranged at the distance from the zero point , the long sides of the first taper structure 322 and the second taper structure 324 are both 1.5 μm, the short sides are both 1 μm, and the distance from the short side to the long side is 1 μm. In this embodiment, a simulation experiment is performed based on the above parameters, and the simulation result is shown in FIG. 12 . According to the simulation structure, it can be known that the insertion loss is 2.38 dB.

Referring to FIG. 13, the phase-shifting device in this embodiment is preferably an aluminum layer 331, and the aluminum layer is disposed at the position where the waveguide structure needs to be powered between the last stage power divider and the transmitting antenna, and is in ohmic contact. As an electrode, it is connected to an external circuit through a gold wire, and the phase of the optical field in the waveguide is modulated by controlling the magnitude of the voltage applied to the phase-shifting device.

的方法)。GaAs晶体属于

晶体点群，在未加电场时，光学性质是各向同性的，其折射率椭球为旋转球面，方程式为：This embodiment will provide a feeding method for an optical phased array (generating

Methods). GaAs crystal belongs to

The crystal point group has isotropic optical properties when no electric field is applied, and its refractive index ellipsoid is a sphere of revolution. The equation is:

Among them, the x ₁ , x ₂ , and x ₃ coordinates in the equation take the direction of the crystal axis, and the linear electro-optic coefficient matrix is:

Therefore, after adding an applied electric field, the induced refractive index ellipsoid becomes:

Among them, E1, E2 and E3 are the electric field components in the directions of x ₁ , x ₂ and x ₃ respectively, n _o is the refractive index of ordinary light, and γ ₄₁ is the linear electro-optic coefficient.

Preferably, the phase-shifting device in this embodiment adopts the applied electric field perpendicular to the 001 crystal plane. At this time, the optical properties of the crystal are changed from isotropic to biaxial crystal, and the three main axes of the induced refractive index ellipsoid are rotated by 45° around the x ₃ axis from the three main axes of the original refractive index ellipsoid, then the induced refractive index is :

Wherein, n′ ₁ , n′ ₂ and n′ ₃ are the induced refractive indices in the directions of x′ ₁ , x′ ₂ and x ₃ , respectively.

When light travels along the _x3 axis, the electro-optic delay is:

When the light propagates along the x' ₁ and x' ₂ directions, the electro-optical delay is:

Among them, x' ₁ and x' ₂ are the directions of the electric field components that are different from x ₁ and x ₂ after power-on, U ₃ is the voltage of the applied electric field in the direction of the optical axis of x ₃ , and U is the voltage along x' ₁ , x' ₂ The applied voltage in the direction, l is the crystal length along the light propagation direction, d is the crystal thickness along the applied voltage direction. Preferably, this embodiment requires that the x ₃ axis of the crystal is along the Y direction.

Referring to FIG. 14 , the transmitting antenna 34 of this embodiment includes a second incident waveguide buffer structure 341 , a second outgoing waveguide buffer structure 343 , and a second incident waveguide buffer structure 341 and a second outgoing waveguide buffer structure 343 disposed between the second incident waveguide buffer structure 341 and the second outgoing waveguide buffer structure 343 . The two-period waveguide grating structure 342, wherein the second periodic waveguide grating structure includes grooves arranged periodically, and the set width D3 of the second incident waveguide buffer structure is equal to the set width D4 of the second exit waveguide buffer structure, preferably Ground, the shape of the transmitting antenna 34 is a bar shape.

Figures 15 and 16 show the simulation results of the coupling efficiency of the transmitting antenna, that is, setting the power monitor on the upper surface of the transmitting antenna to monitor the radiation efficiency. FIG. 15 shows the effect of the etching period on the coupled emission efficiency, and FIG. 16 shows the effect of the etching depth on the emission efficiency. It can be seen from Figure 15 and Figure 16 that when the etching depth (that is, the depth of the waveguide grating groove of the transmitting antenna) is 0.2 m, and the grating period of the transmitting antenna is 0.46 m, the best coupling efficiency in the vertical direction can be obtained. 64%.

Preferably, the grating period T of the transmitting antenna is 0.46 μm, the number of periods is 8, the width E of the waveguide grating groove of the transmitting antenna is 0.3 μm, and the depth of the waveguide grating groove of the transmitting antenna is 0.2 μm. The length of the entire transmitting antenna is 10 μm, and the set width D3 of the second incident waveguide buffer structure and the set width D4 of the second outgoing waveguide buffer structure are both 1 μm.

Preferably, the spacing between adjacent transmitting antennas is 1 μm.

In this embodiment, in order to illustrate that the two-dimensional scanning optical waveguide phased array structure provided in this embodiment can realize fast two-dimensional scanning, the following specific description will be given.

这样就形成了同相波前，实现了光束偏转。理想条件下，光场在各波导芯层独立传输时，光波导阵列的周期性衍射光场分布特性可以通过光栅方程描述。调制后的输出光场的复振幅可以表示成：The one-dimensional scanning in this embodiment utilizes the electro-optic effect of GaAs crystal to independently add a phase to each waveguide array, so that the phase delay difference between adjacent waveguides on the output cross section is

This forms an in-phase wavefront and realizes beam deflection. Under ideal conditions, when the optical field is transmitted independently in each waveguide core layer, the periodic diffraction optical field distribution characteristics of the optical waveguide array can be described by the grating equation. The complex amplitude of the modulated output light field can be expressed as:

The corresponding light intensity distribution is:

In the above formula, α=ka sinθ, a is the width of the waveguide core layer, d is the period width of the waveguide array, θ is the diffraction angle, and λ is the free-space wavelength of the incident light. The light intensity distribution of the untuned waveguide array is:

变成了

使得光强的条纹状分布发生了平移。这样可以利用GaAs的电光效应使波导阵列的芯层产生不同的折射率差Δn，从而得到相邻波导在出射截面上的相差为

随着

的变化光场条纹的位置也发生平移。Compared to the light intensity distribution of the untuned waveguide array, it can be clearly seen that this is due to the multi-slit interference factor.

became

The streak distribution of light intensity is shifted. In this way, the electro-optic effect of GaAs can be used to generate different refractive index differences Δn in the core layer of the waveguide array, so that the difference between adjacent waveguides on the exit cross section can be obtained as

along with

The position of the changing light field fringes also shifts.

Among them, the other dimension adopts wavelength modulation: using a high-speed tunable laser to change the incident wavelength, the rapid change of the far-field distribution of the transmitting antenna array is realized. According to the principle of reversibility of the optical path, the Bragg condition is reversed to obtain the exit angle that satisfies the following formula:

With the waveguide grating structure determined, the exit angle is modulated by the wavelength.

Please refer to FIG. 17. FIG. 17 is a schematic diagram of an electro-optical modulation simulation result provided by an embodiment of the present invention. In this embodiment, matlab is used to obtain the far-field distribution of a light beam with a wavelength of 1.55 μm under the two-dimensional scanning optical waveguide phased array structure. , the solid line in FIG. 17 is the far-field distribution with a scanning angle of 0 degrees, and the dotted line is the far-field distribution with a scanning angle of 15 degrees.

Please refer to FIG. 18 and FIG. 19 , FIG. 18 is the far-field distribution of the transmitting antenna array when the wavelength is 1.4 μm, and FIG. 19 is the far-field distribution of the transmitting antenna array when the wavelength is 1.6 μm. In short, the electro-optic modulation of the two-dimensional scanning optical waveguide phased array structure in this embodiment can realize the up and down movement of the light field in FIG. 17 , and the wavelength modulation can realize the left and right movement of the light field in FIGS. 18 and 19 . Compared with the common two-dimensional optical waveguide phased array, the two-dimensional scanning optical waveguide phased array structure of the embodiment of the present invention can realize two-dimensional simultaneous fast scanning. Please refer to FIG. 20 , which is a schematic diagram of a scanning speed controlled by an electro-optical effect. It can be seen from FIG. 20 that the scanning speed of the two-dimensional scanning optical waveguide phased array structure provided in this embodiment can reach 1 MHz. The scanning speed controlled by the wavelength is determined by the input tunable laser, and the general common high-speed tunable laser can realize the tuning of the order of GHz.

The two-dimensional scanning optical waveguide phased array structure of the embodiment of the present invention selects GaAs and AlGaAs materials on the basis of the original two-dimensional phased array chip, which improves the slow scanning speed of the silicon material two-dimensional phased array chip due to material limitations. The problem of fast 2D scanning is achieved.

The selection of parameters in the embodiments of the present invention is based on the fact that the entire microstructure layer can achieve the best transmission efficiency, and corresponding effects cannot be obtained by simple parameter transplantation for other different materials.

The dual-band frequency scanning antenna of the planar artificial surface proposed in this embodiment solves the problem that the traditional frequency scanning antenna has a single working frequency band and can only perform a single beam scan, and is small in size and low in profile, which is beneficial to the planar integration design.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", " rear, left, right, vertical, horizontal, top, bottom, inside, outside, clockwise, counterclockwise, etc., or The positional relationship is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, Therefore, it should not be construed as a limitation of the present invention.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be considered that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deductions or substitutions can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (10)

1. a fast two-dimensional scanning optical waveguide phased array structure is characterized in that, comprising: a substrate layer, the substrate layer is an n-type doped GaAs material; a buffer layer, disposed on the substrate layer, the buffer layer is a p-type doped Al _0.3 Ga _0.68 As material; A microstructure layer, disposed on the buffer layer, the microstructure layer is an n-type doped GaAs material, wherein the microstructure layer includes a coupling element, a cascaded power divider unit, a phase shift device unit and A transmitting antenna unit, the coupling element, the cascaded power divider unit, the phase-shifting device unit and the transmitting antenna unit are sequentially connected to each other through a waveguide structure, and the phase-shifting device unit includes several phase-shifting devices , the transmitting antenna unit includes a plurality of transmitting antennas, the cascaded power divider units are respectively connected to the phase-shifting devices, and each of the phase-shifting devices is respectively connected to one of the transmitting antennas. 2 . The fast two-dimensional scanning optical waveguide phased array structure according to claim 1 , wherein the coupling element comprises a first incident waveguide buffer structure, a first outgoing waveguide buffer structure, and a first incident waveguide buffer structure arranged on the first incident waveguide buffer structure. 3 . A first periodic waveguide grating structure between the waveguide buffer structure and the first outgoing waveguide buffer structure, wherein the first periodic waveguide grating structure includes periodically arranged grooves, and the setting of the first incident waveguide buffer structure The width gradually decreases to the set width of the first outgoing waveguide buffer structure. 3 . The fast two-dimensional scanning optical waveguide phased array structure according to claim 2 , wherein the shape of the coupling element is a fan shape. 4 . 4 . The fast two-dimensional scanning optical waveguide phased array structure according to claim 1 , wherein the cascaded power divider unit comprises a plurality of power dividers, and each of the power dividers comprises an incident waveguide, A multimode waveguide and two outgoing waveguides, and the incident waveguide and the multimode waveguide are connected by a first taper structure, and a second taper is passed between the multimode waveguide and the two outgoing waveguides respectively Structure is connected. 5 . The fast two-dimensional scanning optical waveguide phased array structure according to claim 1 , wherein the phase-shifting device comprises an aluminum layer, and the aluminum layer is disposed on the cascaded power divider unit and the The waveguide structure between the transmitting antenna units needs to be powered on. 6 . The fast two-dimensional scanning optical waveguide phased array structure according to claim 1 , wherein the transmitting antenna comprises a second incident waveguide buffer structure, a second outgoing waveguide buffer structure, and a second incident waveguide buffer structure arranged on the second incident waveguide. 7 . A second periodic waveguide grating structure between the waveguide buffer structure and the second outgoing waveguide buffer structure, wherein the second periodic waveguide grating structure includes grooves arranged periodically, and the setting of the second incident waveguide buffer structure The width is equal to the set width of the second outgoing waveguide buffer structure. 7 . The fast two-dimensional scanning optical waveguide phased array structure according to claim 6 , wherein the shape of the transmitting antenna is a strip shape. 8 . 8 . The fast two-dimensional scanning optical waveguide phased array structure according to claim 1 , wherein the doping concentration of the microstructure layer is 10 ¹⁸ cm ⁻³ . 9 . The fast two-dimensional scanning optical waveguide phased array structure according to claim 1 , wherein the doping concentration of the substrate layer is 10 ¹⁸ cm ⁻³ . 10 . 10 . The fast two-dimensional scanning optical waveguide phased array structure according to claim 1 , wherein the doping concentration of the buffer layer is 10 ¹⁵ cm ⁻³ . 11 .

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