CN116400453A - High-resolution low-crosstalk phased array scanning chip based on sparse matrix structure - Google Patents
High-resolution low-crosstalk phased array scanning chip based on sparse matrix structure Download PDFInfo
- Publication number
- CN116400453A CN116400453A CN202310206913.8A CN202310206913A CN116400453A CN 116400453 A CN116400453 A CN 116400453A CN 202310206913 A CN202310206913 A CN 202310206913A CN 116400453 A CN116400453 A CN 116400453A
- Authority
- CN
- China
- Prior art keywords
- waveguide
- silicon
- output
- section
- input
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000011159 matrix material Substances 0.000 title claims abstract description 31
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 73
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 50
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 50
- 239000010703 silicon Substances 0.000 claims abstract description 50
- 230000003287 optical effect Effects 0.000 claims abstract description 42
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 36
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 23
- 239000010410 layer Substances 0.000 claims abstract description 19
- 238000005253 cladding Methods 0.000 claims abstract description 16
- 239000012792 core layer Substances 0.000 claims abstract description 12
- 239000000758 substrate Substances 0.000 claims abstract description 8
- 239000011247 coating layer Substances 0.000 claims abstract description 5
- 230000008878 coupling Effects 0.000 claims description 29
- 238000010168 coupling process Methods 0.000 claims description 29
- 238000005859 coupling reaction Methods 0.000 claims description 29
- 238000004519 manufacturing process Methods 0.000 claims description 14
- 230000000737 periodic effect Effects 0.000 claims description 10
- 239000002184 metal Substances 0.000 claims description 2
- 238000009826 distribution Methods 0.000 description 14
- 238000000034 method Methods 0.000 description 8
- 238000013461 design Methods 0.000 description 7
- 230000005540 biological transmission Effects 0.000 description 6
- 238000003780 insertion Methods 0.000 description 6
- 230000037431 insertion Effects 0.000 description 6
- 238000002834 transmittance Methods 0.000 description 4
- 238000003491 array Methods 0.000 description 3
- 238000005311 autocorrelation function Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- 229910052581 Si3N4 Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002070 nanowire Substances 0.000 description 2
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- LDDQLRUQCUTJBB-UHFFFAOYSA-N ammonium fluoride Chemical compound [NH4+].[F-] LDDQLRUQCUTJBB-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000001427 coherent effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000012938 design process Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 238000000609 electron-beam lithography Methods 0.000 description 1
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000001020 plasma etching Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000007704 wet chemistry method Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/12007—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer
- G02B6/12009—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/122—Basic optical elements, e.g. light-guiding paths
- G02B6/1228—Tapered waveguides, e.g. integrated spot-size transformers
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/122—Basic optical elements, e.g. light-guiding paths
- G02B6/124—Geodesic lenses or integrated gratings
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/122—Basic optical elements, e.g. light-guiding paths
- G02B6/125—Bends, branchings or intersections
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12035—Materials
- G02B2006/12061—Silicon
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Power Engineering (AREA)
- Optical Integrated Circuits (AREA)
Abstract
The invention provides a high-resolution silicon optical phased array scanning chip based on a sparse matrix antenna, which comprises a silicon-based substrate, a silicon dioxide buffer layer, a silicon dioxide cladding layer and a core layer based on a silicon waveguide; the core layer comprises a light beam splitting unit, a thermo-optical phase shifter and an emergent grating waveguide array; the light beam splitting unit and the emergent grating waveguide array are positioned in the silicon dioxide coating layer and positioned on the silicon dioxide buffer layer; the thermo-optic phase shifter is arranged on the silicon dioxide cladding; the optical beam splitting unit comprises a plurality of beam splitters based on silicon waveguides; the working bandwidth of the beam splitter is 1450-1750nm. According to the invention, the sparse grating structure is designed by introducing the autocorrelation factors, so that the phase mismatch of light between different waveguides is caused, the grating lobes are restrained from entering the free space by modulating the array factors, the purpose of changing the length of the waveguide grating, namely the sparse is achieved, and therefore, the silicon optical phased array scanning chip with compact structure, high resolution and low crosstalk is provided.
Description
Technical Field
The invention relates to the technical field of chips, in particular to a high-resolution low-crosstalk phased array scanning chip based on a sparse matrix structure.
Background
The phased array system is characterized by rapid beam scanning mode, flexible waveform synthesis and higher transmitting power, so that the phased array system is widely applied to the fields of radar, remote sensing and communication. The phased array matrix determines the key subsystem of the whole phased array system performance, and the quality of the key subsystem directly influences the resolution, the acting distance, the volume and the cost index of the whole system.
Optical Phased Array (OPA) technology offers a promising non-mechanical beam steering at the chip level. Recent advances in silicon photonics provided by many foundry fabrication services have enabled large-scale integrated OPAs to be mass-produced at low cost. Silicon photonics platform provides a strong optical confinement due to high refractive index contrast and well-established Complementary Metal Oxide Semiconductor (CMOS) compatible fabrication processes, allowing small element pitch while maintaining controllable optical loss.
The silicon optical waveguide has the advantages of large refractive index difference of a core cladding, small device size, high integration level, high performance stability and the like, and compared with the existing Silicon On Insulator (SOI) technology, the silicon optical waveguide has the advantages of low manufacturing cost and simple manufacturing process. Because of the excellent characteristics of silicon materials, the research of optical devices of silicon waveguides is wide at home and abroad, such as micro-ring resonant cavities, grating couplers and the like. [ Prior Art: p. ginel-Moreno et al, "Highly efficient optical antenna with small beam divergence in silicon waveguides," Opt. Lett.45,5668-5671 (2020) ". Although the high-resolution silicon optical phased array scanning chip of the sparse matrix has low transmission loss, simple structure and good optical performance and is easy to integrate in a photon integrated circuit, the related report of the high-resolution silicon optical phased array scanning chip of the sparse matrix is not yet seen. Therefore, how to use the sparse matrix silicon beam deflection chip to realize the scanning of the light beam becomes a problem to be solved in the prior art.
In addition, the phased array chip with the traditional structure needs to realize high resolution (small divergence angle), requires larger area of the antenna, and requires smaller space between waveguide antenna arrays in large-field scanning, namely, requires a large-scale waveguide array to realize large antenna area, so that the power consumption of the phase shifter of the chip is larger, and the integrated integration is difficult to realize by using a CMOS control circuit.
Disclosure of Invention
The invention aims to provide a high-resolution low-crosstalk phased array scanning chip which utilizes a small-scale waveguide array to realize high-resolution and wide-field-of-view beam scanning deflection control.
In order to achieve the above purpose, the present invention provides a high resolution low crosstalk phased array scanning chip based on a sparse matrix structure, which comprises a substrate, a silica buffer layer, a silica cladding layer and a core layer based on a silicon waveguide; the silicon dioxide buffer layer is arranged on the substrate, and the core layer is arranged on the silicon dioxide buffer layer and is coated in the silicon dioxide coating layer;
the core layer comprises a plurality of light beam splitting units with the same structural parameters, a thermo-optical phase shifter and an emergent wave array; the visible light beam sequentially passes through the light beam splitting unit, the thermo-optical phase shifter and the emergent waveguide array, so that uniform beam splitting, phase modulation and beam deflection are realized.
Further, the light beam splitting unit and the emergent waveguide array are positioned in the silicon dioxide coating layer and positioned on the silicon dioxide buffer layer; the thermo-optic phase shifter is arranged on the silicon dioxide cladding;
the optical beam splitting unit comprises a plurality of beam splitters based on silicon waveguides; the working bandwidth of the beam splitter is 1450-1750nm; within the operating bandwidth, the non-uniformity between the output ports is less than 0.5dB.
Further, the input beam splitter and the output beam splitter are each provided with 1 input port and 4 output ports.
The beam splitter comprises an input section, a multimode interference coupling section and an output section which are connected in sequence;
the input section comprises an input straight waveguide section and an input conical waveguide section connected with the input straight waveguide section; the large end of the input conical waveguide section is connected with the multimode interference coupling section;
the output section comprises 4 output conical waveguide sections and output straight waveguide sections which are respectively connected with the output conical waveguide sections; the large end of the output conical waveguide section is connected with the multimode interference coupling section.
Further, the multimode interference coupling section has a width of 12um; the length of the multimode interference coupling section is 60um; the length of the multimode interference coupling section is fabricated to a tolerance range of-4% to +4%.
Further, when the working wavelength of the beam splitter is 1550nm, the total output power of the beam splitter is greater than 90% within the manufacturing tolerance range.
Further, the length of the input tapered waveguide section is 2um, and the width of the large end of the input tapered waveguide section is 2.2um; the width of the small end of the input conical waveguide section is 0.5um; the widths of the input straight waveguide section and the output straight waveguide section are 0.5um, and the lengths of the input straight waveguide section and the output straight waveguide section are 8um; the interval between the output straight waveguide sections is 1.5um;
the width of the large end of the output conical waveguide section is 2.2um; the width of the small end of the output conical waveguide section is 0.5um; the length of the output tapered waveguide section is 2um.
Further, the thermo-optic phase shifter is a metal heater; the thermo-optic phase shifter is disposed on the output channel of the beam splitter splitting unit.
Further, the thickness of the silica cladding is 1um.
Further, the emergent wave array comprises a plurality of waveguide gratings with different lengths and adjacent to each other, the waveguide gratings are composed of etching straight waveguides with the length of 400um, the width of each waveguide grating is 0.5um so as to basically maintain a single-mode condition, and the gap between the adjacent waveguide gratings is 1.5um;
further, the waveguide grating is a silicon periodic grating, the period of the two adjacent silicon periodic gratings is 0.3-0.4um, the duty ratio is 0.5-0.8, the width is 0.12um, and the number of gratings is 1500-2000; the interval between the silicon periodic gratings is 0.5um; two adjacent silicon periodic grating arrangements meet the Costas matrix.
Compared with the prior art, the invention has the advantages that:
1) The invention is based on the novel semiconductor material silicon, has small size, compact structure, simple processing, large manufacturing tolerance and high product yield.
2) The waveguide array can reduce the crosstalk between waveguides in 1550nm optical wave bands, realize high transmittance and low insertion loss, and has important practical value in the field of optical phased arrays; in addition, the invention still keeps lower insertion loss and crosstalk within the 1550nm wavelength range, and the bandwidth reaches 80nm.
3) The sparse waveguide array structure can realize large-angle scanning in the aspect of light beam scanning, the area array sparse distribution rate is lower than 0.5, and the gain is approximately equivalent to that of a full array, and the sparse waveguide array structure is characterized in that through an intermediate sparse grating structure, the phase mismatch of light among different waveguides is caused, grating factors are modulated to inhibit grating lobes from entering free space, so that the purpose of increasing unit spacing, namely sparseness, is achieved, and therefore, the silicon optical phased array scanning chip with compact structure, high resolution and low crosstalk is provided, and has important application prospects in the fields of high-density integrated waveguide elements, optical phased arrays, solid laser radars with large light beam scanning angles and the like. The manufacturing equipment of the invention is compatible with commercial CMOS manufacturing equipment, so that mass production with low cost can be realized.
Drawings
FIG. 1 is a block diagram of a sparse matrix high resolution silicon optical phased array scanning chip in accordance with an embodiment of the present invention;
FIG. 2 is a block diagram of the beam splitter of FIG. 1;
FIG. 3 is a cross-sectional view of a high resolution silicon optical phased array scan chip of the sparse matrix at the beam splitter of FIG. 2;
FIG. 4 is a graph of the field distribution of light transmission in a beam splitter based on a time domain finite difference method of the present invention modeling the incidence of light at a center wavelength of 1550 nm;
FIG. 5 is a graph of normalized energy output of each output port when light with a center wavelength of 1450-1750nm is simulated by using simulation software Lumerical FDTD Solutions based on a time domain finite difference method;
FIG. 6 is a diagram of a far-field scanning angle of a sparse matrix high-resolution silicon optical phased array scanning chip, based on a time domain finite difference method, using simulation software Lumerical FDTD Solutions to simulate incidence of light with a center wavelength of 1450-1750nm;
fig. 7 is a flow chart of the fabrication of a sparse matrix high resolution silicon optical phased array scanning chip according to an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be further described below.
As shown in fig. 1 and 3, a high-resolution silicon optical phased array scanning chip capable of being based on a sparse matrix antenna comprises a silicon substrate 5, a silicon dioxide buffer layer 6, a silicon dioxide cladding layer 8 and a core layer 7 of a silicon waveguide; a silicon dioxide buffer layer 6 is provided on the silicon-based substrate 5; a silica cladding layer 8 is attached to the silica buffer layer 6; the core layer 7 comprises an optical beam splitting unit, a thermo-optical phase shifter 3 and an emergent waveguide array 4; the visible light beam sequentially passes through the light beam splitting unit, the thermo-optical phase shifter 3 and the emergent waveguide array 4, so that uniform beam splitting, phase modulation and beam deflection are realized; the light beam splitting unit and the emergent waveguide array 4 are positioned in the silica cladding 8 and positioned on the silica buffer layer 7; the thermo-optic phase shifter 3 is arranged on the silica cladding 8; the optical beam splitting unit comprises a plurality of beam splitters based on silicon nitride waveguides; the working bandwidth of the beam splitter is 1450-1750nm.
In this embodiment, the input beam splitter is in series with the output beam splitter; the input beam splitters are each provided with 1 input port and 4 output ports. Ensuring that each beam passes through the same propagation path when reaching the exit waveguide array 4, i.e. ensuring that the phases are the same.
As shown in fig. 2, the beam splitter includes an input section, a multimode interference coupling section, and an output section connected in sequence; the input section comprises an input straight waveguide section and an input conical waveguide section connected with the input straight waveguide section; the large end of the input conical waveguide section is connected with the multimode interference coupling section; the output section comprises 4 output conical waveguide sections and output straight waveguide sections which are respectively connected with the output conical waveguide sections; the large end of the output conical waveguide section is connected with the multimode interference coupling section. Specifically, the width e of the multimode interference coupling section is 12um; the length d of the multimode interference coupling section is 60um; the length d of the multimode interference coupling section is manufactured to have a tolerance range of-4% to +4%; the length b of the input conical waveguide section is 2um, and the width c of the large end of the input conical waveguide section is 2.2um; the width of the small end of the input conical waveguide section is 0.5um; the width a of the input straight waveguide section and the width of the output straight waveguide section are both 0.5um, and the length is both 8um; the interval between the output straight waveguide sections is 1.5um; the width f of the large end of the output conical waveguide section is 2.2um; the width of the small end of the output conical waveguide section is 0.5um; the length g of the output tapered waveguide section is 8um.
When the working wavelength of the beam splitter is set to be 1550nm, the output total power of the beam splitter under different lengths is more than 90% in the length manufacturing tolerance range on the basis that the optimal length of the multimode interference coupling section is 60 microns, namely the length d of the multimode interference coupling section is changed. When the optimal coupling width of the coupling section is 12um, the non-uniformity among the output ports under the condition of different working wavelengths is less than 0.5dB by setting the working bandwidth of the beam splitter, namely inputting the visible light with different wavelengths under the condition of not changing the specification of the beam splitter. Wherein the total output power of the beam splitter is the ratio of the total output energy of the 4 output ports to the input energy of one input port.
In the present embodiment, the input beam splitter 1 and the output beam splitter 2 have the same structure. In design, the optimal coupling lengths corresponding to the waveguides with different widths under 1550nm wavelength incidence and the optimal structure of the output waveguide are calculated. Specifically, the parameter design process of the input beam splitter 1 and the output beam splitter 2 is as follows: in order to optimize the optical coupling of an input beam and an output beam, improve the efficiency of the beam splitter, and improve the working performance of the multi-stage beam splitting unit, namely 1 input beam splitter 1 and 4 output beam splitters 2 in the working wave band, when the multi-stage beam splitting unit is designed, an optical waveguide model based on a conical structure is introduced, and the problem of low-loss design in a common method is solved. The method comprises the following specific steps:
firstly, calculating the length of a coupling area according to the selected incident wavelength lambda and the waveguide width of the coupling area, and then, primarily obtaining the device parameters of uniform beam splitting of a theoretical visible light wave band; then optimizing design parameters of the 1450-1750nm band silicon optical beam splitter by a time domain finite difference method of calculation electromagnetics, so that TE polarized light with the center wavelength of 1550nm is uniformly split into 4 paths of output with consistent phase and light intensity.
The transmission loss of 1550nm in the heart wavelength in operation of the input beam splitter 1 and the output beam splitter 2 after the design optimization is less than 0.1dB, the non-uniformity among the output ports is less than 0.1dB, and the uniform output ratio of 0.1dB for TE polarized light can be realized.
In the present embodiment, the thermo-optic phase shifter 3 is a heater; the thermo-optic phase shifter 3 is attached to the silica cladding 8 and placed at the output of the beam splitting unit. The phase shifter adopting the thermo-optical modulator structure realizes high-efficiency and low-loss phase control. The thermo-optic phase shifter 3 is electrically heated the core layer 7, whereas the refractive index of the core layer 7 based on a silicon nitride waveguide is temperature dependent, thereby controlling the phase of the light passing through the waveguide. If the thermo-optic phase shifter 3 is closer to the output beam splitter 2, the modulation efficiency is higher, but the thermo-optic phase shifter 3 has an absorption effect on the light transmitted in the waveguide, resulting in a larger light transmission loss; however, if the thermo-optic phase shifter 3 is located farther from the output beam splitter 2, the transmission loss of light is small and the modulation efficiency is not high. The thickness of the silica cladding 8 was chosen to be 1um, which ultimately tradeoffs the effect of different electrode positions and morphologies on modulation efficiency and optical transmission loss. To accomplish the phase control with high efficiency and low loss, the heater part is made of Ti/Pt metal material with high resistance, the thickness of the heater is 100nm, and the area of the heater is 250 multiplied by 5um 2 The method comprises the steps of carrying out a first treatment on the surface of the The electrode part of the heater connected with an external current source is made of a Ti/Au metal material with low resistivity, so that the efficiency of the heater is higher and the loss is smaller.
For the design of the sparse periodic grating, the grating structure with the same period and duty ratio is etched on a sparse straight waveguide to achieve the effect of inhibiting waveguide coupling, one periodic grating structure is selected, the period is 0.3-0.4um, the duty ratio is 0.5-0.8, the width is 0.12um, and the number of gratings is 1500-2000. The gap between adjacent waveguide grating structures is 0.5um.
For comparison of performance parameters, η incident is the transmittance of light incident from an incident port, η coupled is the transmittance of an output waveguide coupled to an input waveguide, η pass-through is the transmittance of an output waveguide port through which the input waveguide passes. The eta through of the optimized structure can reach 86.7 percent, and the eta coupling is as low as 0.8 percent. The correlation index was that the Insertion Loss (IL) was 10lg ((ηthrough+ηcoupling)/ηincident) and the peak crosstalk was 10lg (ηthrough/ηcoupling).
For the design of a grating arrangement, each point on the wavefront of the propagating wave can be considered a point source, and the wavefront at any subsequent point can be found by summing the contributions from each individual point source, according to the huygens-fresnel principle. An ideal diffraction grating can be considered to consist of a set of equally spaced infinitely long infinitely narrow slits, the spacing between the slits being d, known as the grating constant. When a plane wave with the wavelength lambda is vertically incident on the grating, the point on each slit plays the role of a secondary wave source; light rays emitted from these secondary wave sources propagate in all directions (i.e., spherical waves). Since the slit is infinitely long, only the case in a plane perpendicular to the slit can be considered, i.e. the slit is reduced to a row of points in the plane. The light field in a particular direction in this plane is coherently superimposed by the light emerging from each slit. When interference occurs, since the phases of the light emitted from each slit at the interference points are different, they are partially or completely canceled. First, understanding the theory of single slit diffraction and multi-slit coherent constructive interference of gratings, when the optical path difference between the light rays emitted from two adjacent slits and reaching the interference point is an integer multiple of the wavelength of the light, the two light rays have the same phase, and an interference strengthening phenomenon occurs. Then, according to the theory, a general relation between the intensity distribution of the Far Field (FFP) and the Near Field (NFP) of the N-path antenna OPA is deduced, because the far field intensity distribution of the antenna is obtained by the near field through Fourier transformation, the light intensity of the far field is the square of the complex amplitude distribution of the far field, the relation between the near field intensity distribution and the light intensity can be obtained through carrying-in conversion, and the influence of the displacement vector on the light intensity can be obtained through a light intensity formula after conversion.
The near field distribution of the antenna is:
the far-field complex amplitude distribution of the antenna is:
F(ξ)＝∫∫E(r)exp[ik 0 (r.ξ)]d 2 r
the light intensity distribution in the far field is:
I(ξ)＝|F(ξ)| 2 ＝∫∫∫E(r)E*(r)exp[ik 0 (r-r′)·ξ]d 2 rd 2 r′＝∫∫R EE (Δ)exp[ik 0 (Δ·ξ)]d 2 Δ
R EE and (delta) represents the autocorrelation function of the near field distribution in the spatial domain. And it can be expressed as:
R EE (Δ)＝R uu (Δ)*R AA (Δ)
introducing an autocorrelation coefficient of the antenna arrangement:
where Δ=r-r', Δ=r n -r m Delta is the delta function of Dirac, which is the autocorrelation function of the electric field distribution and array layout from each antenna, respectively. Because the convolution of the electric field distribution autocorrelation function of each antenna array layout and the antenna can obtain the far-field light intensity distribution through Fourier transformation, the arrangement mode of the antenna matrix can directly influence the far-field light intensity distribution condition. The arrangement form of the Costas matrix can realize finer sampling resolution on the premise of realizing far-field optical field coherence constructive.
The finally designed sparse matrix high-resolution silicon optical phased array scanning chip can realize TE polarized light input in 1450-1750nm wave bands, the coupling phenomenon among waveguides is obviously improved, the insertion loss is low, the crosstalk is reduced, the large-angle scanning can be realized in the aspect of beam deflection, and the sparse matrix high-resolution silicon optical phased array scanning chip can be applied in the aspects of optical phased array and scanning.
(II) device fabrication
First, a silicon oxide film is plated on a silicon-on-insulator (SOI) substrate as a mask for etching the waveguide. And then preparing the waveguide by using electron beam lithography, plasma etching and the like, and monitoring the etching depth in real time to obtain the silicon waveguide with a flat surface. Then, the sample is etched by silicon dioxide, and a certain amount of ammonia fluoride is added into HF corrosive liquid to be used as a buffer, so that corrosive liquid Buffer Hydrogen Fluoride (BHF) is formed and used for removing silicon dioxide on the surface of the silicon waveguide. And removing impurities on the surface of the silicon by wet chemical process cleaning (RCA), plating a silicon dioxide coating layer on the silicon waveguide by using Plasma Enhanced Chemical Vapor Deposition (PECVD), and finally cutting the sample.
The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art will make any equivalent substitution or modification to the technical solution and technical content disclosed in the invention without departing from the scope of the technical solution of the invention, and the technical solution of the invention is not departing from the scope of the invention. The invention provides an array waveguide grating with the assistance of nano wires, which can realize high uniformity under the condition of low insertion loss. And the overall size of the waveguide grating will remain unchanged when the nanowire is introduced.
The high-resolution silicon optical phased array scanning chip of the sparse matrix antenna provided by the invention is simple in design and easy to manufacture, has no extra insertion loss, can be produced in a large scale at low cost, and is expected to be widely applied to highly integrated radar systems.
The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art will make any equivalent substitution or modification to the technical solution and technical content disclosed in the invention without departing from the scope of the technical solution of the invention, and the technical solution of the invention is not departing from the scope of the invention.
Claims (10)
1. A high-resolution low-crosstalk phased array scanning chip based on a sparse matrix structure comprises a substrate, a silicon dioxide buffer layer, a silicon dioxide cladding layer and a core layer based on a silicon waveguide; the silicon dioxide buffer layer is arranged on the substrate, and the core layer is arranged on the silicon dioxide buffer layer and is coated in the silicon dioxide coating layer;
the core layer comprises a plurality of light beam splitting units with the same structural parameters, a thermo-optical phase shifter and an emergent wave array; the visible light beam sequentially passes through the light beam splitting unit, the thermo-optical phase shifter and the emergent waveguide array, so that uniform beam splitting, phase modulation and beam deflection are realized.
2. The sparse matrix structure based high resolution low crosstalk phased array scan chip of claim 1, wherein the optical splitting unit and exit waveguide array are located within the silica cladding and on the silica buffer layer; the thermo-optic phase shifter is arranged on the silicon dioxide cladding;
the optical beam splitting unit comprises a plurality of beam splitters based on silicon waveguides; the working bandwidth of the beam splitter is 1450-1750nm; within the operating bandwidth, the non-uniformity between the output ports is less than 0.5dB.
3. The sparse matrix structure based high resolution low crosstalk phased array scan chip of claim 2, wherein the input splitter and the output splitter are each provided with 1 input port and 4 output ports.
The beam splitter comprises an input section, a multimode interference coupling section and an output section which are connected in sequence;
the input section comprises an input straight waveguide section and an input conical waveguide section connected with the input straight waveguide section; the large end of the input conical waveguide section is connected with the multimode interference coupling section;
the output section comprises 4 output conical waveguide sections and output straight waveguide sections which are respectively connected with the output conical waveguide sections; the large end of the output conical waveguide section is connected with the multimode interference coupling section.
4. A sparse matrix structure based high resolution low crosstalk phased array scan chip according to claim 3, wherein the width of said multimode interference coupling segments is 12um; the length of the multimode interference coupling section is 60um; the length of the multimode interference coupling section is fabricated to a tolerance range of-4% to +4%.
5. The sparse matrix structure based high resolution low crosstalk phased array scan chip of claim 4, wherein the total output power of the beam splitter is greater than 90% within the fabrication tolerance range when the operating wavelength of the beam splitter is 1550nm at the center wavelength.
6. The sparse matrix high resolution silicon optical phased array scan chip of claim 3, wherein the length of the input tapered waveguide segment is 2um and the width of the large end of the input tapered waveguide segment is 2.2um; the width of the small end of the input conical waveguide section is 0.5um; the widths of the input straight waveguide section and the output straight waveguide section are 0.5um, and the lengths of the input straight waveguide section and the output straight waveguide section are 8um; the interval between the output straight waveguide sections is 1.5um;
the width of the large end of the output conical waveguide section is 2.2um; the width of the small end of the output conical waveguide section is 0.5um; the length of the output tapered waveguide section is 2um.
7. The sparse matrix high resolution silicon optical phased array scan chip of claim 1, wherein the thermo-optic phase shifter is a metal heater; the thermo-optic phase shifter is disposed on the output channel of the beam splitter splitting unit.
8. The sparse matrix high resolution silicon optical phased array scan chip of claim 7, wherein the silica cladding has a thickness of 1um.
9. The sparse matrix high resolution silicon optical phased array scan chip of claim 1, wherein the emergent wave array comprises a plurality of waveguide gratings disposed adjacent to each other in different lengths, the waveguide gratings comprising 400um long etched straight waveguides having a width of 0.5um to substantially maintain a single mode condition, and a gap between adjacent waveguide gratings being 1.5um.
10. The sparse matrix high resolution silicon optical phased array scan chip of claim 9, wherein the waveguide grating is a silicon periodic grating, the period of adjacent two silicon periodic gratings is 0.3-0.4um, the duty cycle is 0.5 to 0.8, the width is 0.12um, and the number of gratings is 1500 to 2000; the interval between the silicon periodic gratings is 0.5um; two adjacent silicon periodic grating arrangements meet the Costas matrix.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310206913.8A CN116400453A (en) | 2023-03-07 | 2023-03-07 | High-resolution low-crosstalk phased array scanning chip based on sparse matrix structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310206913.8A CN116400453A (en) | 2023-03-07 | 2023-03-07 | High-resolution low-crosstalk phased array scanning chip based on sparse matrix structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116400453A true CN116400453A (en) | 2023-07-07 |
Family
ID=87018744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310206913.8A Pending CN116400453A (en) | 2023-03-07 | 2023-03-07 | High-resolution low-crosstalk phased array scanning chip based on sparse matrix structure |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116400453A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117784313A (en) * | 2024-02-28 | 2024-03-29 | 之江实验室 | Two-dimensional photon convolution operation chip and system based on cyclic array waveguide grating |
-
2023
- 2023-03-07 CN CN202310206913.8A patent/CN116400453A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117784313A (en) * | 2024-02-28 | 2024-03-29 | 之江实验室 | Two-dimensional photon convolution operation chip and system based on cyclic array waveguide grating |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Sun et al. | Large-scale silicon photonic circuits for optical phased arrays | |
| Ding et al. | Metasurface-dressed two-dimensional on-chip waveguide for free-space light field manipulation | |
| CN108398842B (en) | Optical phased array chip based on serial optical antenna | |
| Mühlenbernd et al. | Amplitude-and phase-controlled surface plasmon polariton excitation with metasurfaces | |
| US20170307810A1 (en) | Diffraction structure, diffraction grating, diffraction grating array, optical phased array, optical modulator, optical filter, laser source | |
| WO2012092828A1 (en) | Method for manufacturing multi-dimensional target waveguide grating and volume grating with micro-structure quasi-phase-matching | |
| CN112034550B (en) | Silicon nitride phased array chip based on suspended waveguide structure | |
| WO2001014929A1 (en) | Integrated hybrid optoelectronic devices | |
| CN116400453A (en) | High-resolution low-crosstalk phased array scanning chip based on sparse matrix structure | |
| CN112764287A (en) | Half-wave two-dimensional scanning optical phased array based on flat grating antenna | |
| Zhang et al. | Integrated optical true time delay network based on grating-assisted contradirectional couplers for phased array antennas | |
| Jiang et al. | Design and analysis of a two-dimensional large-scale silicon-photonic optical phased array | |
| CN112255724A (en) | Waveguide array based on lithium niobate and manufacturing method thereof | |
| Oh et al. | Adjoint-optimized metasurfaces for compact mode-division multiplexing | |
| Liu et al. | Metainterface and application for high-performance spectro-polarimetric filter | |
| CN112180506B (en) | High-density low-crosstalk waveguide array based on micro-nano isolation structure | |
| Liu et al. | Thermally tunable silicon nitride sampled gratings in polymer | |
| CN114755759A (en) | Ultra-compact arrayed waveguide grating wavelength division multiplexer based on sub-wavelength grating | |
| JP2004219986A (en) | Holographic wave transmission medium, waveguide circuit, and manufacturing methods therefor | |
| Chen et al. | On-chip slow-light sin bragg grating waveguides | |
| Zeng et al. | All-optical microwave filters using uniform fiber Bragg gratings with identical reflectivities | |
| CN112415663A (en) | Mach-Zehnder broadband low-power-consumption optical switch based on multi-stage microdisk coupling | |
| JP3936865B2 (en) | Light switch | |
| Yang et al. | Highly-efficient thin film LiNbO 3 surface couplers connected by ridge-waveguide subwavelength gratings | |
| CN218332239U (en) | Optical phased array based on sub-wavelength grating and snake-shaped phase shifter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |