A two-dimensional phased array lidar based on hybrid integrated waveguide

Abstract

The present invention proposes a two-dimensional phased array laser radar based on a hybrid integrated waveguide, including: a fiber laser, a splitter, a multi-layer hybrid integrated waveguide, an output device and other structures; each layer of the hybrid integrated waveguide includes a lithium niobate modulation module and an optical waveguide, the lithium niobate modulation module and the optical waveguide are embedded and integrated, and an electric control system is provided in the lithium niobate module, and the electric control system is used to act on the lithium niobate module for phase modulation. The fiber laser is connected to the splitter, and the splitter divides the input light into multiple paths of light and outputs them to the input end of the corresponding hybrid integrated waveguide, and the output device collimates the emitted light after interference and outputs it. By adopting the method of multi-layer stacking of hybrid integrated waveguides, the emission direction of the laser is changed by adjusting the relative phase of the light, so as to realize two-dimensional scanning of the emitted laser, which has the advantages of large scanning angle, high scanning accuracy, fast response rate, and high integration.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fiber communication and laser radar, and in particular relates to a two-dimensional phased array laser radar based on a hybrid integrated waveguide. Background Art

[0002] LiDAR is a system that emits laser beams to detect the position, speed and other characteristic quantities of a target. It is widely used in the field of laser detection. Traditional mechanical scanning radars are costly, bulky, power-hungry, and heavy. In addition, they are susceptible to many unstable effects when rotating at high speeds, and the devices need to be calibrated frequently. Phased array LiDAR, on the other hand, has overcome these shortcomings very well. Not only that, it also has the advantages of high sensitivity and efficient multi-target detection. Compared with traditional mechanically controlled beam steering technology, it has a faster response speed and greatly improves pointing accuracy and stability. Optical phased array LiDAR is expected to be widely used in autonomous driving, robotics, imaging, drones, healthcare, and the Internet of Things in the next decade.

[0003] Optical phased array laser radar, the optical waveguide array realizes beam scanning by powering up, using the electro-optical effect of optical waves to load voltage on the waveguide core layer, so that each waveguide core layer has a different additional refractive index, and a specific phase difference is generated between the array waveguides through modulation. The phase difference is distributed according to a certain rule to cause the deflection scanning of the output beam. Compared with mechanical rotation and MEMS beam scanning solutions, optical phased array radar does not contain rotating elements, and has the advantages of fast scanning speed, large scanning range, high integration, high reliability and low cost.

[0004] A schematic diagram of an optical phased array laser radar system application structure provided by the prior art is shown in the attached manual. Figure 1 As shown, the optical signal pulse emitted by the laser light source is incident on the phased array scanning system, the emission light beam of the phased array scanning system is emitted to the object to be measured for scanning, and the optical signal pulse after diffuse reflection by the object to be measured is received by the reflected light receiving device and then enters the signal processing device.

[0005] There are three traditional methods for controlling the direction of light beams based on optical phased arrays: the first is to use electro-optical crystals to manufacture optical phased arrays, and control the phase of the incident light by using the different refractive indices of birefringent crystals under different intensities of electric fields; the second is to use the acousto-optic effect to manufacture optical phased arrays, and use the periodic changes in the local refractive index of the crystal caused by the passage of ultrasound through the crystal to form controllable Bragg diffraction, so that the angle of the first-order diffraction light can be controlled; the third is an optical phased array made using the thermo-optic effect. However, the first control method has a short service life and high power consumption; the second control method is not conducive to integrated production and has a high cost; the third control method has high power consumption and low energy utilization. A single optical waveguide phased array uses processes such as ion implantation and ion diffusion, and it is difficult to make a high refractive index difference structure, accurately control the phase difference, and achieve precise range scanning. Summary of the invention

[0006] In view of this, in order to fill the gap in the prior art and overcome the defects and deficiencies of the prior art, the present invention provides a two-dimensional phased array laser radar based on a hybrid integrated waveguide, including: a fiber laser, a splitter, a multi-layer hybrid integrated waveguide, an output device and other structures; each layer of the hybrid integrated waveguide includes a lithium niobate modulation module and an optical waveguide, the lithium niobate modulation module is embedded and integrated with the optical waveguide, and an electric control system is provided in the lithium niobate module, and the electric control system is used to act on the lithium niobate module for phase modulation. The fiber laser is connected to the splitter, and the splitter divides the input light into multiple paths of light and outputs them to the input end of the corresponding hybrid integrated waveguide, and the output device collimates the emitted light after interference and outputs it. By adopting the method of multi-layer stacking of hybrid integrated waveguides, the emission direction of the laser is changed by adjusting the relative phase of the light, and the two-dimensional scanning of the emitted laser is realized, which has the advantages of large scanning angle, high scanning accuracy, fast response rate, and high integration.

[0007] The present invention specifically adopts the following technical solutions:

[0008] A two-dimensional phased array laser radar based on a hybrid integrated waveguide, characterized by:

[0009] It comprises: a fiber laser (1), a splitter (2), a multi-layer hybrid integrated waveguide (31-3N) and an output device (4);

[0010] Each layer of the hybrid integrated waveguide (31-3N) comprises a lithium niobate modulation module and an optical waveguide constituting embedded integration; the lithium niobate module is provided with an electric control system for performing phase modulation on the lithium niobate modulation module;

[0011] The optical fiber laser (1) is connected to a splitter (2), the splitter (2) splits the input light into multiple lights and connects them to the input ends of corresponding multi-layer hybrid integrated waveguides (31-3N), and the output device (4) collimates and outputs the interfered light 41; the multi-layer hybrid integrated waveguide (31-3N) changes the emission direction of the laser by adjusting the relative phase of the light, so as to realize two-dimensional scanning of the emitted laser in the horizontal direction θx and the vertical direction θy.

[0012] Furthermore, the multilayer hybrid integrated waveguides (31-3N) are stacked at a spacing d that can produce an interference effect at the light output end: d=nλ, λ is the wavelength of the input laser light signal, and n is 1, 2...n; the interference light is collimated and output after passing through the output device (4), so as to achieve scanning of the output light beam in the vertical direction θy.

[0013] Furthermore, each of the lithium niobate modulation modules is provided with N channels formed by cutting, and deep grooves are engraved between each channel, with a total of N-1 deep grooves, so as to isolate the mutual influence between the electrodes;

[0014] For each layer of hybrid integrated waveguide, signal light is input into the hybrid integrated waveguide. After the input light is divided into N light paths at the front of the optical waveguide, the light paths correspond to the channels of the lithium niobate modulation module respectively. The N light paths after phase modulation by the lithium niobate modulation module enter the rear of the optical waveguide and are combined into an interference array structure, so that the N light paths with phase differences form interference light paths, which are then collimated and output through an output device (4). The emission direction of the interference light paths is changed by adjusting the relative phase of the N light paths, thereby finally realizing the scanning of the output light path in the horizontal direction θx.

[0015] Furthermore, the electric control system controls the electrodes of each channel of the lithium niobate modulation module individually.

[0016] Furthermore, the front and rear surfaces of the lithium niobate modulation module are plated with optical anti-reflection films to reduce light beam insertion loss.

[0017] Furthermore, the shape of the optical waveguide where it is embedded in the lithium niobate modulation module is horn-shaped, which is used to transform the light beam in the optical waveguide from a divergent light beam to a parallel light beam passing through the lithium niobate modulation module, and then re-converge back into the optical waveguide.

[0018] Furthermore, the front input end of the optical waveguide is a light 1xN branching structure, and the rear output end is a structure that is closed and connected to an interference array.

[0019] Compared with the prior art, the present invention and its preferred embodiment have the following beneficial effects:

[0020] Compared with traditional mechanical scanning radars, the laser radar of the present invention has small size, low power consumption, high sensitivity, fast response speed and high stability; in addition, compared with the traditional single optical waveguide optical phased array, the present invention adopts lithium niobate modulation module and optical waveguide hybrid integrated waveguide to accurately modulate the phase difference of each channel, with a large adjustable phase shift range, and has the advantages of large scanning angle, high scanning accuracy, fast response rate and high integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0022] Figure 1 It is a schematic diagram of the application structure of an optical phased array laser radar system in the prior art.

[0023] Figure 2 It is a schematic diagram of the principle structure of a two-dimensional phased array laser radar according to an embodiment of the present invention.

[0024] Figure 3 It is a schematic diagram of the x-direction scanning principle structure of a two-dimensional phased array laser radar according to an embodiment of the present invention.

[0025] Figure 4 It is a schematic diagram of the y-direction scanning principle structure of a two-dimensional phased array laser radar according to an embodiment of the present invention.

[0026] Figure 5 It is a schematic diagram of the structure of a lithium niobate modulation module according to an embodiment of the present invention.

[0027] Figure 6 Schematic diagram of the structure of the optical waveguide embedding part according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the features and advantages of this patent more obvious and easy to understand, the following embodiments are specifically described in detail as follows:

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] like Figure 2 As shown, an embodiment of the present invention provides a structure of a two-dimensional phased array laser radar based on a hybrid integrated waveguide, which includes: a fiber laser 1, a splitter 2, a multi-layer hybrid integrated waveguide 31~3N and an output device 4.

[0031] Among them, each layer of the multi-layer hybrid integrated waveguide 31~3N has the same structure. Taking the first layer of hybrid integrated waveguide 31 as an example, it includes a lithium niobate modulation module 31b and an optical waveguide 31a. The lithium niobate modulation module 31b and the optical waveguide 31a are embedded and integrated. The lithium niobate module 31b is provided with an electric control system, and the electric control system is used to act on the lithium niobate module for phase modulation.

[0032] The fiber laser 1 is connected to the splitter 2, which splits the input light 11 into multiple light paths (21, 22...2N), which are further connected to the input ends of the corresponding multi-layer hybrid integrated waveguides (31, 32...3N), and the output device 4 collimates and outputs the interfered light 41. The multi-layer hybrid integrated waveguide (31, 32...3N) changes the emission direction of the laser by adjusting the relative phase of the light, thereby realizing two-dimensional scanning of the emitted laser 41 in the horizontal direction θx and the vertical direction θy.

[0033] In this embodiment, a multi-layer hybrid integrated waveguide is used, which is stacked in a stacked manner at a spacing sufficient to produce an interference effect at the light output end, thereby realizing two-dimensional spatial scanning.

[0034] Preferably, the lithium niobate modulation module (ie, lithium niobate photoelectric modulator) is embedded in the optical waveguide integrated hybrid waveguide.

[0035] Preferably, deep grooves are engraved between the channels of the lithium niobate modulation module to isolate the electrodes from affecting each other.

[0036] Preferably, each channel electrode of the lithium niobate modulation module is controlled individually, the phase shift can be precisely modulated, and the adjustable range of the phase shift is large.

[0037] The embedding part of the optical waveguide is designed to be horn-like, so that the light in the optical waveguide passes through the lithium niobate modulation module in parallel and then converges back into the optical waveguide.

[0038] The front input end of the optical waveguide is used to realize the optical 1xN branching structure, and the rear output end is closed to the interference array structure.

[0039] Based on the above device structure, the specific implementation process of the present invention is as follows:

[0040] like Figure 2 As shown, in the embodiment of the present invention, the fiber laser 1 emits a laser light signal 11, the laser light signal 11 is input into the splitter 2, the splitter 2 splits the laser light signal 11 into multiple light paths (21, 22...2N), and the multiple light paths enter the input end of the corresponding multi-layer hybrid integrated waveguide (31, 32...3N).

[0041] The signal light 21 is input to the hybrid integrated waveguide 31, the signal light 22 is input to the hybrid integrated waveguide 32, and so on. From the perspective of the single-layer hybrid integrated waveguide 31, the interference light of the signal light 21 after phase modulation by the single-layer hybrid integrated waveguide 31 is collimated and output after passing through the output device 4, so as to realize horizontal direction θx scanning as shown in FIG. Figure 3 shown.

[0042] The interference light after phase modulation of the multi-path light (21, 22...2N) is respectively passed through the multi-layer hybrid integrated waveguide (31, 32...3N) and then collimated and outputted through the output device 4, so as to realize vertical θy scanning as shown in FIG. Figure 4 As shown, the emitted laser 41 is thereby subjected to two-dimensional scanning in the horizontal direction θx and the vertical direction θy.

[0043] like Figure 3 , which is a schematic diagram of the x-direction scanning principle structure of a two-dimensional phased array laser radar according to an embodiment of the present invention.

[0044] Select one layer of hybrid integrated waveguide 31 for specific description. Lithium niobate modulation module 31b is embedded in optical waveguide 31a to integrate hybrid waveguide 31. Signal light 21 is input into hybrid integrated waveguide 31. Signal light 21 first enters the front part of optical waveguide 31a of hybrid integrated waveguide 31. The front part of optical waveguide 31a divides input light 21 into N paths of light, 211, 212...21N respectively. Then, N paths of light correspond to each channel of lithium niobate modulation module 31b respectively. After phase modulation by lithium niobate modulation module 31b, N paths of light beams enter the rear part of optical waveguide 31a. The rear part of optical waveguide 31a is closed into interference array structure. N paths of light beams with phase difference form interference light beam 41. Interference light beam 41 is collimated and output through output device 4. The emission direction of interference light beam 41 is changed by adjusting the relative phase of N paths of light beams, and finally the output light beam is scanned in horizontal direction θx.

[0045] like Figure 4 As shown, it is a schematic diagram of the principle structure of the two-dimensional phased array laser radar in the y direction according to an embodiment of the present invention:

[0046] The multilayer hybrid integrated waveguide (31, 32...3N) is stacked at a spacing sufficient to produce an interference effect at the light output end, d=nλ, λ is the wavelength of the input laser light signal, and n is 1, 2...n; the interference light 41 is collimated and output after passing through the output device 4, so that the output light beam is scanned in the vertical direction θy.

[0047] like Figure 5The figure shows a schematic diagram of the structure of the lithium niobate modulation module of an embodiment of the present invention. The lithium niobate modulation module 31b is cut into N channels, and deep grooves are cut between each channel, with N-1 deep grooves. The deep grooves are cut to isolate the mutual influence between electrodes and realize accurate modulation of the phase of each channel; the lithium niobate modulation module 31b is provided with an electric control system, the bottom is a common electrode 51, and the upper electrode is set separately for each channel, namely 521, 522...52N. Each channel electrode is controlled separately, the phase shift can be accurately modulated, and the adjustable range of the phase shift is large; the front and back surfaces 53 and 54 of the lithium niobate modulation module 31b are plated with optical anti-reflection films to reduce beam insertion loss.

[0048] like Figure 6 , which is a schematic diagram of the structure of the optical waveguide embedding part according to an embodiment of the present invention.

[0049] The lithium niobate modulation module 31b is embedded in the optical waveguide 31a to integrate the hybrid waveguide 31. The optical waveguide 31a is designed to be horn-shaped where it is embedded in the lithium niobate modulation module 31b, so that the light beam in the optical waveguide 31a changes from a divergent light beam to a parallel light beam, then passes through the lithium niobate modulation module 31b in parallel, and then converges back to the optical waveguide 31a. This structural design makes the light beam loss through the lithium niobate modulation module 31b very small.

[0050] This patent is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of a two-dimensional phased array lidar based on a hybrid integrated waveguide under the inspiration of this patent. All equal changes and modifications made according to the scope of the patent application of the present invention should be covered by this patent.

Claims

1. A two-dimensional phased array laser radar based on a hybrid integrated waveguide, characterized in that: include: Fiber laser (1), splitter (2), multilayer hybrid integrated waveguide (31-3N) and output device (4); Each layer of the hybrid integrated waveguide (31-3N) comprises a lithium niobate modulation module and an optical waveguide constituting embedded integration; the lithium niobate module is provided with an electric control system for performing phase modulation on the lithium niobate modulation module; The optical fiber laser (1) is connected to a splitter (2), the splitter (2) splits the input light into multiple lights and connects them to the input ends of corresponding multi-layer hybrid integrated waveguides (31-3N), and the output device (4) collimates and outputs the interfered light (41); the multi-layer hybrid integrated waveguide (31-3N) changes the emission direction of the laser by adjusting the relative phase of the light, so as to realize two-dimensional scanning of the emitted laser in the horizontal direction θx and the vertical direction θy; The multilayer hybrid integrated waveguides (31-3N) are stacked at a spacing d that can produce an interference effect at the light output end: d=nλ, λ is the wavelength of the input laser light signal, and n is 1, 2...n; the interference light passes through the output device (4) and is collimated and output, so as to achieve scanning of the output light beam in the vertical direction θy; Each of the lithium niobate modulation modules is provided with N channels formed by cutting, and deep grooves are engraved between each channel, with a total of N-1 deep grooves, so as to isolate the mutual influence between the electrodes; For each layer of hybrid integrated waveguide, signal light is input into the hybrid integrated waveguide. After the input light is divided into N light paths at the front of the optical waveguide, the light paths correspond to the channels of the lithium niobate modulation module respectively. The N light paths after phase modulation by the lithium niobate modulation module enter the rear of the optical waveguide and are combined into an interference array structure, so that the N light paths with phase differences form interference light paths, which are then collimated and output through an output device (4). The emission direction of the interference light paths is changed by adjusting the relative phase of the N light paths, thereby finally realizing the scanning of the output light path in the horizontal direction θx.

2. The two-dimensional phased array laser radar based on hybrid integrated waveguide according to claim 1, characterized in that: The electric control system controls the electrodes of each channel of the lithium niobate modulation module individually.

3. The two-dimensional phased array laser radar based on hybrid integrated waveguide according to claim 1, characterized in that: The front and back surfaces of the lithium niobate modulation module are plated with optical anti-reflection films to reduce light beam insertion loss.

4. The two-dimensional phased array laser radar based on hybrid integrated waveguide according to claim 1, characterized in that: The shape of the optical waveguide where it is embedded in the lithium niobate modulation module is horn-shaped, which is used to transform the light beam in the optical waveguide from a divergent light beam to a parallel light beam passing through the lithium niobate modulation module, and then re-converge back into the optical waveguide.

5. The two-dimensional phased array laser radar based on hybrid integrated waveguide according to claim 1, characterized in that: The front input end of the optical waveguide is a light 1xN branching structure, and the rear output end is a structure that is closed and connected to an interference array.

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