High-speed scanning large-aperture optical phased array
By employing a silicon substrate and multilayer structure design in optical phased arrays, combined with electrode-controlled phase modulation, the problems of high-speed scanning and uniform emission of large-aperture beams in optical phased arrays have been solved, enabling the fabrication of high-performance, low-cost optoelectronic devices.
Patent Information
- Application Number
- CN202421160889.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-27
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2034-05-27
AI Technical Summary
Existing technologies make it difficult to achieve high-speed scanning of optical phased arrays without laying other materials, and traditional chemical etching methods are difficult to process lithium niobate materials.
The structure employs a silicon substrate, a buried oxide layer of silicon dioxide, a lithium niobate layer, and a silicon nitride layer. Combined with a multimode interference coupler and a non-uniform grating antenna, the uniform emission of the beam is achieved by controlling the phase modulation of the lithium niobate layer through electrodes.
It achieves high-speed beam scanning and large-aperture uniform emission, reduces processing difficulty and cost, and improves device integration and reliability, making it suitable for fields such as optical communication, lidar, and 3D sensing.
Smart Images
Figure CN223582283U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field of optoelectronic devices, concretely relates to high -speed scanning large aperture optical phased array. BACKGROUND
[0002] Optical phased arrays (OPA) are phase-adjustable optical antenna arrays, whose working principle is similar to that of microwave phased arrays. By controlling the phase of the light radiated by each optical antenna, the beam can be steered without the need for a mechanical servo system. Compared with traditional optical communication terminals, OPA has the advantages of fast steering speed, agile beam, multi-beam steering, small size, and light weight. Photonic integrated OPA integrates all necessary components such as light sources, power dividers, amplifiers, phase shifters, and optical antennas on a chip using complementary metal-oxide-semiconductor (CMOS) technology. Therefore, photonic integrated OPA has the potential to realize a chip-level beam control system and reduce the cost of space optical communication terminals.
[0003] Lithium niobate (LiNbO3, LN) is one of the most promising materials in the field of integrated photonics, with high electro-optic coefficient, high nonlinear coefficient, wide transparent window (400nm-5μm), and stable chemical properties. These outstanding characteristics make LN an ideal choice for the manufacture of high-speed modulators and other optoelectronic devices. However, since LN is a chemically inert material, it is difficult to process using traditional chemical etching methods. To address this challenge, a new method has been introduced in recent years, namely the hetero-integrated indirect etching method based on load materials and lithium niobate on insulator (LNOI). The core idea of this method is to deposit a layer of load material with similar optical properties to LN on LNOI, and then etch the load material to form a load material-lithium niobate hetero-optical waveguide. Through this design, direct etching of LN can be avoided during device manufacturing, while ensuring the performance and stability of the optical waveguide. This hetero-integrated indirect etching method based on load materials and lithium niobate on insulator provides a new solution for the manufacture of high-performance LN optoelectronic devices. It fully utilizes the excellent properties of LN and combines mature preparation processes, bringing broader prospects for the application of LN in the field of integrated photonics. SUMMARY
[0004] Therefore, in view of the above technical problems, the high-speed scanning large-aperture optical phased array can achieve high-speed scanning of the optical phased array without laying other materials. The non-uniform grating design can increase the effective aperture of the antenna and achieve uniform emission of the optical beam.
[0005] Based on the above purpose, the high-speed scanning large-aperture optical phased array comprises:
[0006] The silicon substrate, the silicon dioxide buried oxygen layer, the lithium niobate layer, the silicon nitride layer and the silicon dioxide cladding layer, the silicon dioxide buried oxygen layer is arranged on the upper surface of the silicon substrate, the lithium niobate layer is arranged on the upper surface of the silicon dioxide buried oxygen layer, and the silicon nitride layer is arranged on the upper surface of the lithium niobate layer, wherein the silicon nitride layer is used as a waveguide.
[0007] The silicon nitride layer comprises: an MMI cascaded light splitting area for splitting light power into two parts, a phase modulation area for changing the phase of the waveguide, and an antenna area for emitting light into space; the input light power is uniformly divided into 128 parts by cascading the MMI of the 1:2 splitter, the effective refractive index of each waveguide is changed by the electrical modulation of the lithium niobate layer when passing through the phase modulation area, thereby changing the phase, and then the light is uniformly emitted into space by the antenna of the non-uniform grating to realize large-angle scanning.
[0008] The MMI coupling area, the width of the rectangular waveguide is set to be in the range of 6-8 μm, and the length of the rectangular waveguide is set to be in the range of 21-28 μm; the non-uniform grating antenna area, the duty cycle of the grating is 0.5, and the perturbation depth is set to be in the range of 50-400 nm.
[0009] Preferably, the MMI in the light splitting area splits the light power into two parts, the input is a rectangular silicon nitride waveguide, the middle MMI coupling area is a larger size rectangular silicon nitride waveguide, and the output is two rectangular silicon nitride waveguiders with the same size as the input.
[0010] Preferably, the phase modulation area for changing the phase of the waveguide, the silicon nitride waveguide layer is arranged above the lithium niobate layer, the first electrode and the second electrode are arranged on both sides of each silicon nitride waveguide, and the second electrode of each waveguide except the last waveguide is also the first electrode of the next waveguide. The first electrode is used to connect the positive electrode of the power supply, and the second electrode is used to connect the negative electrode of the power supply. By applying different voltage signals to the electrodes acting on the lithium niobate layer, the same phase difference is formed between each waveguide.
[0011] Preferably, the antenna area for emitting light beams, the antenna is a fishbone grating, and as the length of the antenna increases, the perturbation value β of the fishbone grating also changes.
[0012] Preferably, the height of the silicon substrate is greater than the height of the silicon dioxide buried oxygen layer, the height of the silicon dioxide buried oxygen layer is greater than the height of the lithium niobate layer, the height of the lithium niobate layer is equal to the height of the silicon nitride layer, and the height of the silicon dioxide cladding layer is equal to the height of the silicon dioxide buried oxygen layer.
[0013] Preferably, the high-speed scanning large-aperture optical phased array is characterized in that the height of the silicon substrate is 500 μm.
[0014] Preferably, the high-speed scanning large-aperture optical phased array is characterized in that the height of the buried oxide layer of silicon dioxide is 3 mu m.
[0015] Preferably, the high-speed scanning large-aperture optical phased array is characterized in that the height of the lithium niobate layer is 300 nm.
[0016] Preferably, the high-speed scanning large-aperture optical phased array is characterized in that the height of the silicon nitride layer is 300 nm.
[0017] Preferably, the multi-mode interference coupling region, the width of the rectangular waveguide is set in the range of 6-8 mu m, and the length of the rectangular waveguide is set in the range of 21-28 mu m; the duty cycle of the grating in the non-uniform grating antenna area is 0.5, and the perturbation depth is set in the range of 50-400 nm.
[0018] Compared with the prior art, the high-speed scanning large-aperture optical phased array has the following beneficial effects:
[0019] 1. By growing a silicon nitride film on a lithium niobate substrate as a waveguide layer, the excellent electro-optic modulation characteristics of lithium niobate are utilized, and the difficulty in processing is overcome. The organic combination of the two is expected to realize high-performance, low-cost, and process-simplified integrated optoelectronic devices.
[0020] 2. The multi-stage MMI beam splitting structure can realize efficient and uniform optical power distribution, effectively reduce beam splitting loss, and ensure the consistency of each signal, which is crucial for stable operation of large-scale phased arrays.
[0021] 3. The phase modulation area utilizes the electro-optic effect of lithium niobate to realize phase modulation, and simplifies the control circuit through a common electrode structure, greatly improving the integration and reliability of the device.
[0022] 4. The non-uniform grating antenna array adopts a gradual perturbation design, which not only obtains a large aperture and narrow beam, but also suppresses sidelobes and improves transmission efficiency. This is the key to realizing high-gain and low-loss beam scanning.
[0023] 5. The entire device uses silicon-based planar technology, which is compatible with existing CMOS technology, facilitating large-scale integration and low-cost manufacturing. This will greatly promote the application of phased array technology in optical communication, laser radar, three-dimensional sensing, and other fields.
[0024] 6. The phased array scheme of the utility model has the characteristics of small size, light weight, low power consumption, and fast response speed, and is especially suitable for satellite communication, unmanned driving, laser radar, and other harsh requirements for miniaturization and light weight. BRIEF DESCRIPTION OF DRAWINGS
[0025] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0026] Figure 1 This is a top view of a high-speed scanning large-aperture optical phased array provided in an embodiment of this utility model;
[0027] Figure 2 This is a layered structure diagram of the high-speed scanning large-aperture optical phased array provided in the embodiments of this utility model;
[0028] Figure 3 This is a diagram of the non-uniform grating structure of the high-speed scanning large-aperture optical phased array provided in Embodiment 1 of this utility model;
[0029] The symbols are explained as follows:
[0030] 1. Beam splitter region; 2. Phase modulation region; 3. Antenna region; 4. Silicon nitride layer; 5. Lithium niobate layer; 6. Buried oxide layer; 7. Silicon substrate; 8. Grating structure with a perturbation depth of 50 nm; 9. Grating structure with a perturbation depth of 100 nm; 10. Grating structure with a perturbation depth of 150 nm; 11. Grating structure with a perturbation depth of 200 nm; 12. Grating structure with a perturbation depth of 250 nm; 13. Grating structure with a perturbation depth of 300 nm; 14. Grating structure with a perturbation depth of 350 nm; 15. Grating structure with a perturbation depth of 400 nm; Detailed Implementation
[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model.
[0032] like Figure 2 The high-speed scanning large-aperture optical phased array shown has four main layers, from bottom to top: n4, n3, n2, and n1. The n4 layer is a silicon substrate, the n3 layer is a silicon dioxide buried oxide layer 6, the n2 layer is a lithium niobate layer 5, and the n1 layer is a silicon nitride layer 4. The height of the silicon substrate 7 is greater than the height of the silicon dioxide buried oxide layer 6, the height of the silicon dioxide buried oxide layer 6 is greater than the height of the lithium niobate layer 5, and the height of the lithium niobate layer 5 is equal to the height of the silicon nitride layer 4.
[0033] The structure of the silicon nitride layer 4 is shown in Figure 1 The light splitting area 1 includes an input waveguide, 28 1-to-2 MMI, 7 groups of curved waveguides, the first group has 2 curved waveguides, the second group has 4 curved waveguides, the third group has 8 curved waveguides, the fourth group has 16 curved waveguides, the fifth group has 32 curved waveguides, the sixth group has 64 curved waveguides, and the seventh group has 128 curved waveguides. The phase modulation area includes 128 straight waveguides, each of which has electrodes on both sides, a total of 129 electrodes. The antenna area has 128 grating antennas, as shown in Figure 3 There are 8 different grating perturbation depths, including grating structure 8 with a perturbation depth of 50 nm, grating structure 9 with a perturbation depth of 100 nm, grating structure 10 with a perturbation depth of 150 nm, grating structure 11 with a perturbation depth of 200 nm, grating structure 12 with a perturbation depth of 250 nm, grating structure 13 with a perturbation depth of 300 nm, grating structure 14 with a perturbation depth of 350 nm, and grating structure 15 with a perturbation depth of 400 nm.
[0034] The MMI in the light splitting area 1 splits the optical power into two, with an input of a rectangular silicon nitride waveguide, a middle multimode interference coupling area of a larger size rectangular silicon nitride waveguide, and an output of two rectangular silicon nitride waveguiders with the same size as the input. The size of the rectangular silicon nitride waveguide in the multimode interference coupling area depends on the following formula:
[0035]
[0036]
[0037] The position of the output waveguide depends on the following formula:
[0038] ;
[0039] wherein, is the effective refractive index of the waveguide, is the central working wavelength, and β is the perturbation value; is the position of the output waveguide, is the output waveguide number, is the total mode number of the multimode interference area.
[0040] The phase modulation area for changing the phase of the waveguide is provided with a lithium niobate layer and a silicon nitride waveguide layer above the lithium niobate layer, and each silicon nitride waveguide is provided with a first electrode and a second electrode on both sides, and the second electrode of each waveguide except the last waveguide is also the first electrode of the next waveguide. The first electrode is used for connecting the positive electrode of the power supply, and the second electrode is used for connecting the negative electrode of the power supply. By applying different voltage signals to the electrodes to act on the lithium niobate layer, the same phase difference is formed between each waveguide.
[0041] The antenna area for emitting light beams is a fishbone grating, and as the length of the antenna increases, the disturbance value β of the fishbone grating also changes, satisfying the following formula:
[0042]
[0043] In the system, the materials of all components in the silicon nitride layer 4 are silicon nitride (i.e., each waveguide, one-to-two MMI, and grating), and the heights of all waveguides, one-to-two MMIs, and gratings are consistent, and the height of each component in the silicon nitride layer 4 is 300 nm. In the system, the height of the silicon substrate (i.e., the height of the n4 layer in the silicon substrate 7) is 500 μm, the height of the silicon dioxide buried oxygen layer (i.e., the height of the n3 layer in the silicon dioxide buried oxygen layer 6) is 3 μm, and the height of the lithium niobate layer (i.e., the height of the n2 layer in the lithium niobate layer 5) is 300 nm, that is, the height of the silicon substrate 7 is greater than the height of the silicon dioxide buried oxygen layer 6, the height of the silicon dioxide buried oxygen layer 6 is greater than the height of the lithium niobate layer 5, and the height of the lithium niobate layer 5 is equal to the height of the silicon nitride layer 4. Figure 2 Figure 2 Figure 2
[0044] In the system, the light source used is a tunable narrow linewidth laser, the tuning range is 1500-1600 nm, and the linewidth is 80 kHz.
[0045] The working principle of the system is as follows:
[0046] As shown in Figure 1 , the high-speed scanning large-aperture optical phased array includes an input waveguide, an optical splitting area, a curved connecting waveguide, a phase modulation area, an output connecting waveguide, and a transmitting antenna area from left to right. The laser light source enters the straight waveguide through end face coupling, the light is split through the multi-stage one-to-two MMI cascaded optical splitting area, the light is uniformly divided into 128 paths, the optical power of the 128 paths is equal, the phases are the same, the 128 paths enter the phase modulation area through the connecting curved waveguide, the refractive index of the lithium niobate layer 5 is changed by applying electricity to the electrodes, the phases of the 128 paths are modulated, and then the 128 paths enter the transmitting antenna area through the output connecting waveguide. The grating disturbance depth gradually increases from left to right, the effective length of the antenna is increased, and thus the large-aperture uniform emission is realized.
[0047] Compared with the prior art, the high-speed scanning large-aperture optical phased array has the following advantages:
[0048] (1) The high-speed scanning optical phased array on lithium niobate is realized by fully utilizing the high electro-optic coefficient, high nonlinear coefficient, wide transparent window (400 nm-5 mu m) and stable chemical property characteristics of LN, and combining the mature preparation process.
[0049] (2) The system is integrated on a silicon-based chip, is easy to mass-produce in actual production, and has the advantages of small size, high flexibility, simple structure and convenience for compatibility with other systems.
[0050] (3) The antenna area used by the system is an antenna array composed of non-uniform gratings, the grating disturbance depth gradually increases from left to right, the effective length of the antenna is increased, and large-aperture uniform emission is realized.
[0051] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can make equivalent replacement or change according to the technical scheme and the practical concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.
Claims
1. A high-speed scanning large-aperture optical phased array, characterized in that, include: The invention comprises a silicon substrate, a buried oxide layer of silicon dioxide, a lithium niobate layer, a silicon nitride layer, and a silicon dioxide cladding layer, wherein the buried oxide layer of silicon dioxide is disposed on the upper surface of the silicon substrate, the lithium niobate layer is disposed on the upper surface of the buried oxide layer of silicon dioxide, and the silicon nitride layer is disposed on the upper surface of the lithium niobate layer, wherein the silicon nitride layer serves as a waveguide. The silicon nitride layer includes: an optical beam splitting region for cascading multimode interference couplers to split optical power in two, a phase modulation region for changing the waveguide phase, and an antenna region for transmitting light into space. The optical beam splitting region contains a multimode interference coupler that splits the optical power into two parts. The input is a rectangular silicon nitride waveguide, the middle multimode interference coupling region is a larger rectangular silicon nitride waveguide, and the output consists of two rectangular silicon nitride waveguides with the same size as the input. The width of the rectangular silicon nitride waveguide is set in the range of 6-8 μm, and the length of the rectangular silicon nitride waveguide is set in the range of 21-28 μm; the antenna region is a non-uniform grating structure, the duty cycle of the grating is 0.5, and the perturbation depth is set in the range of 50-400 nm.
2. The optical phased array according to claim 1, characterized in that, The phase-tuning region used to change the waveguide phase consists of a silicon nitride waveguide layer above a lithium niobate layer. Each silicon nitride waveguide has a first electrode and a second electrode on both sides. Except for the last waveguide, the second electrode of each other waveguide is also the first electrode of the next waveguide. The first electrode is used to connect to the positive terminal of the power supply, and the second electrode is used to connect to the negative terminal of the power supply. By applying different voltage signals to the electrodes to the lithium niobate layer, the same phase difference is formed between each waveguide.
3. The optical phased array according to claim 1, characterized in that, The antenna region used to emit the light beam has a fishbone-shaped grating as its antenna.
4. The optical phased array according to claim 1, characterized in that, The height of the silicon substrate is greater than the height of the silicon dioxide buried oxide layer, the height of the silicon dioxide buried oxide layer is greater than the height of the lithium niobate layer, the height of the lithium niobate layer is equal to the height of the silicon nitride layer, and the height of the silicon dioxide cladding is equal to the height of the silicon dioxide buried oxide layer.
5. The optical phased array according to claim 1, characterized in that, The height of the silicon substrate is 500 μm.
6. The optical phased array according to claim 1, characterized in that, The height of the buried oxide layer in the silica is 3 μm.
7. The optical phased array according to claim 1, characterized in that, The height of both the lithium niobate layer and the silicon nitride layer is 300 nm.