A wide-angle scanning optical phased array and laser radar

Abstract

The present invention specifically relates to a wide-angle scanning optical phased array and laser radar, wherein the optical phased array comprises: a laser, a beam splitting network, an optical amplifier array, a phase shifter array, and an antenna array arranged in sequence; the antenna array comprises a plurality of waveguide antennas arranged side by side; and any of the waveguide antennas comprises a main channel waveguide and a photonic crystal grating arranged on both sides of the main channel waveguide. The present invention forms evanescent coupling through the main channel waveguide and the photonic crystal gratings on both sides thereof, so that after the optical signal is transmitted through the main channel waveguide, it is coupled to the photonic crystal gratings on both sides under the action of evanescent coupling, and then diffracted into free space by the photonic crystal grating, forming a beam scan. At the same time, the light beam diffracted into free space is transmitted by the slow wave of the photonic crystal in the photonic crystal grating, which doubles the longitudinal scanning angle of the optical phased array provided by the present invention.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to an optical phased array and a laser radar for wide-angle scanning. Background Art

[0002] A phased array is an array of phase-controlled elements. It achieves beam steering by adjusting the phase of the outgoing wave from each element. Compared to traditional mechanically controlled beam steering techniques, it offers faster response times and significantly improved pointing accuracy and stability. Optical phased arrays operate in the optical frequency band and are used for point-to-point free-space optical communications, optical detection and measurement, holographic imaging, and vortex light generation.

[0003] In the field of laser radar, two-dimensional scanning of lasers can be achieved through phased array technology. However, due to the composition structure of the phased array, it is difficult to achieve a wide range of scanning angles, which limits the scanning range of the phased array-based laser radar and restricts the application scenarios of the laser radar. Summary of the Invention

[0004] In order to solve the technical problem of limited scanning range of laser radar using phased array technology in the prior art, a wide-angle scanning optical phased array and laser radar are provided, which have at least the advantages of wide scanning angle and small size.

[0005] First aspect

[0006] The present invention provides an optical phased array for wide-angle scanning, comprising:

[0007] A laser, a beam splitting network, an optical amplifier array, a phase shifter array, and an antenna array are arranged in sequence;

[0008] The antenna array includes multiple groups of waveguide antennas;

[0009] Any of the waveguide antennas includes a main channel waveguide and photonic crystal gratings arranged on both sides of the main channel waveguide.

[0010] Furthermore, the photonic crystal grating includes a silicon strip and photonic crystals arranged on the silicon strip and distributed in an array;

[0011] The adjacent photonic crystals are non-uniformly distributed.

[0012] Furthermore, a coupling gap is provided between the silicon strip and the main channel waveguide;

[0013] The coupling gap is 220nm-250nm.

[0014] Optionally, the radius of the photonic crystal is 75nm-100nm; the lattice constant of the photonic crystal is 450nm-500nm.

[0015] Furthermore, the laser comprises at least two groups of broadband tunable lasers connected in series.

[0016] Furthermore, the beam splitting network includes a multi-stage Y-type beam splitter, a multimode interference beam splitter or a star-coupled beam splitter.

[0017] Optionally, the optical amplifier array is arranged in each branch of the beam splitting network.

[0018] Optionally, the phase shifter array includes a silicon-based electro-optical phase shifter, a thermo-optical phase shifter or a III-V MOS phase shifter.

[0019] Optionally, the laser, beam splitting network, optical amplifier array, phase shifter array and antenna array are all made of III-V Group materials and are heterogeneously integrated into a single chip.

[0020] Second aspect

[0021] The present invention provides a laser radar, comprising an optical phased array for wide-angle scanning as described in any embodiment of the first aspect.

[0022] In summary, the present invention provides a wide-angle scanning optical phased array and laser radar with at least the following advantages:

[0023] 1. One of the main concepts of the present invention is to form evanescent coupling through the main channel waveguide and the photonic crystal gratings on both sides. After the optical signal is transmitted through the main channel waveguide, it is coupled to the photonic crystal gratings on both sides under the action of evanescent coupling. Then, it is diffracted into free space by the photonic crystal grating, forming a beam scanning. At the same time, the light beam diffracted into free space is transmitted by the slow wave of the photonic crystal in the photonic crystal grating, which doubles the longitudinal scanning angle of the optical phased array provided by the present invention, thereby providing the advantage of wide-angle scanning.

[0024] 2. Another key concept of the present invention is to design the arrangement of photonic crystal-based waveguide antennas to achieve a non-uniform distribution. This overcomes the technical problem of limited lateral field of view caused by excessive center-to-center spacing when uniformly arranged photonic crystal-based waveguide antennas are arranged, thereby achieving a larger array area while providing a larger lateral field of view.

[0025] 3. Another key concept of the present invention is to design the radius and lattice constant of the photonic crystal to achieve a slow-light effect within the target wavelength, thereby improving the dispersion of light and, in turn, enhancing the scanning sensitivity of the antenna array.

[0026] 4. One of the main concepts of the present invention is to design the laser structure in series, thereby doubling the longitudinal scanning angle of the optical phased array provided by the present invention, thereby increasing the scanning width of the phased array provided by the present invention;

[0027] 5. Based on the above technical concept, the present invention further provides a laser radar on the basis of the optical phased array, so that when the laser radar uses the phased array for two-dimensional scanning, the longitudinal scanning angle is doubled and the lateral angle reaches ±60°, thereby giving the laser radar provided by the present invention broader application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be described in further detail below with reference to the accompanying drawings and preferred embodiments. However, those skilled in the art will appreciate that these drawings are drawn only for the purpose of explaining the preferred embodiments and should not be construed as limiting the scope of the present invention. Furthermore, unless otherwise specified, the drawings are merely schematic representations of the composition or structure of the depicted objects and may contain exaggerated representations. Furthermore, the drawings are not necessarily drawn to scale.

[0029] Figure 1 A schematic structural diagram of an optical phased array for wide-angle scanning provided by one embodiment of the present invention;

[0030] Figure 2 A schematic structural diagram of a photonic crystal waveguide antenna provided by one embodiment of the present invention;

[0031] Figure 3 A schematic diagram showing a sensitivity comparison of a photonic crystal grating provided by an embodiment of the present invention;

[0032] Figure 4 A schematic diagram comparing the radius and lattice constant of a photonic crystal provided by one embodiment of the present invention;

[0033] Figure 5 A schematic diagram comparing the far-field intensity distribution at 0° and 60° transverse scanning angles provided by an embodiment of the present invention;

[0034] Figure 6 A schematic diagram of attenuation loss of a coupling gap provided by an embodiment of the present invention;

[0035] 1. Laser; 2. Beam splitting network; 3. Optical amplifier array; 4. Phase shifter array; 5. Antenna array; 6. Substrate; 51. Waveguide antenna; 511. Main channel waveguide; 512. Photonic crystal grating; 513. Coupling gap; 512a. Silicon strip; 512b. Photonic crystal. DETAILED DESCRIPTION

[0036] The following is combined with Figures 1 to 6, the present invention is described in detail.

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to 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.

[0038] The main technical concept of the present invention is to expand the scanning range of the optical phased array through the structural design of the laser 1 and the antenna array 5 on the basis of the existing optical phased array, thereby improving its application prospects in the field of laser radar.

[0039] See Figure 1 FIG2 is a schematic structural diagram of an optical phased array for wide-angle scanning provided by an embodiment of the present invention.

[0040] Specifically, the optical phased array provided by the present invention includes a laser 1, a beam splitting network 2, an optical amplifier array 3, a phase shifter array 4, and an antenna array 5, which are arranged in sequence. Laser 1 can adopt different microring radii to correspond to different ranges of laser resonant wavelengths, thereby covering different wavelength bands. The beam splitting network 2 is used to split the resonant laser light generated by laser 1 and amplify the resonant laser light in the beam splitting network 2 through the optical amplifier array 3. The resonant laser light is then adjusted by the phase shifter array 4, thereby achieving power amplification of the scanning laser light ultimately emitted by the antenna array 5.

[0041] For further information, see Figure 2 FIG. 5 is a schematic structural diagram of a photonic crystal 512b waveguide antenna 51 provided in one embodiment of the present invention.

[0042] The antenna array 5 provided by the present invention includes multiple groups of waveguide antennas 51 arranged in parallel. Each waveguide antenna 51 includes a main channel waveguide 511 and photonic crystal gratings 512 arranged on both sides of the main channel waveguide 511. The main channel waveguide 511 and the photonic crystal grating 512 are both arranged on a substrate 6. A coupling gap 513 is reserved between the main channel waveguide 511 and the photonic crystal grating 512. The provision of the coupling gap 513 separates the main channel waveguide 511 and the photonic crystal grating 512, ensuring that diffracted light from the photonic crystal grating 512 does not affect the transmission of signal light in the main channel waveguide 511. Adjusting the coupling gap can adjust the light coupling strength, thereby allowing the preparation of waveguide antennas 51 of different lengths.

[0043] In addition, the photonic crystal grating 512 includes a silicon strip 512a and multiple groups of photonic crystals 512b etched on the silicon strip 512a. Since the parameters of the photonic crystals 512b are set in the photonic bandgap, slow light transmission can be achieved, thereby achieving the purpose of increasing the longitudinal angle.

[0044] Furthermore, the photonic crystals 512b in the photonic crystal grating 512 utilize a non-uniform sparse array, overcoming the limited lateral field of view caused by the large center-to-center spacing in a uniform array arrangement. This allows for both a larger array area and a larger lateral field of view. The far-field intensity distribution of the waveguide antenna 51 array based on the non-uniform distribution of photonic crystals 512b achieves a horizontal field of view of ±60°, allowing a 128-channel array to fill a 1mm wide lateral aperture. A larger array area results in a smaller divergence angle.

[0045] It is worth explaining that the array composed of the non-uniformly distributed waveguide antennas 51 based on photonic crystals 512 b can be obtained by particle swarm optimization, genetic algorithm or other optimization algorithms.

[0046] Optionally, taking a genetic algorithm as an example, the element positions of a non-uniform array are defined as optimization variables, a population is randomly generated, each individual represents a possible array layout, and the sidelobe suppression ratio is used as the fitness function. The selection, crossover, mutation, replacement, optimization and other algorithmic processes are iterated to finally obtain the optimized result (array coordinate group).

[0047] Furthermore, the divergence angle of the phased array is inversely proportional to the effective aperture area of ​​the non-uniform array.

[0048] Alternatively, laser 1 can be implemented by connecting two or more laser components in series within the main channel silicon waveguide, each outputting optical signals in a different wavelength range. Since the longitudinal scanning angle range of the optical phased array is controlled by the wavelength range, increasing the number of lasers 1 can directly double the longitudinal scanning angle. Each laser component can be independently controlled.

[0049] For further information, see Figure 3 FIG. 1 is a schematic diagram showing a sensitivity comparison of a photonic crystal grating 512 provided in accordance with an embodiment of the present invention.

[0050] Specifically, the present invention utilizes the slow light effect to increase the longitudinal scanning range to more than 30° (typical value 15° / 100 nm) within the wavelength range of 1500-1600 nm.

[0051] For further information, see Figure 4 FIG. 1 is a schematic diagram showing a comparison of the radius and lattice constant of a photonic crystal 512 b provided in an embodiment of the present invention.

[0052] Specifically, the lattice constant of the photonic crystal 512 b is 480 nm, and the energy band diagram of the photonic crystal 512 b when the radius is 95 nm has a photonic band gap covering a wavelength range of 1500-1600 nm.

[0053] Optionally, when the lattice constant of the photonic crystal 512b increases, the diffraction angle of the waveguide antenna 51 deflects toward the positive direction, so that the lattice constant of the photonic crystal 512b can be determined based on the light output angle of the waveguide antenna 51, and thus can be adapted to the needs of optical phased arrays with different light output angles.

[0054] For further information, see Figure 5 FIG2 is a schematic diagram showing the comparison of far-field intensity distribution at 0° and 60° transverse scanning angles provided by an embodiment of the present invention.

[0055] Specifically, when the photonic crystal 512b array adopts a non-uniform sparse distribution, the lateral scanning angle can reach ±60°.

[0056] For further information, see Figure 6 FIG. 1 is a schematic diagram of the attenuation loss of a coupling gap provided by an embodiment of the present invention.

[0057] Specifically, the coupling gap 513 is 220 nm-250 nm.

[0058] Optionally, when the width of the main channel waveguide 511 is 500 nm, the width of the silicon strip 512a is 300 nm, the lattice constant of the photonic crystal 512b is 480 nm, and the radius is 95 nm, Figure 6 The wavelength of the waveguide antenna 51 shown in (a) is 1550 nm.

[0059] Optionally, when the coupling gap 513 is 240nm, the attenuation loss of the waveguide antenna 51 in the 1500nm-1600nm band is 2dB / mm, and thus the setting of the coupling gap 513 can effectively regulate the coupling strength, thereby controlling the attenuation loss of the waveguide antenna 51 and improving the signal transmission quality of the antenna array 5.

[0060] The present invention has been described in detail above. Specific examples have been used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only intended to help understand the present invention and its core concepts. It should be noted that those skilled in the art may make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. An optical phased array for wide-angle scanning, characterized in that: include: A laser (1), a beam splitting network (2), an optical amplifier array (3), a phase shifter array (4), and an antenna array (5) are arranged in sequence; The antenna array (5) includes multiple groups of waveguide antennas (51) arranged side by side; Any of the waveguide antennas (51) comprises a main channel waveguide (511) and photonic crystal gratings (512) arranged on both sides of the main channel waveguide (511); The photonic crystal grating (512) comprises a silicon strip (512a) and photonic crystals (512b) arranged on the silicon strip (512a) and distributed in an array. The photonic crystal (512b) in the photonic crystal grating (512) adopts a non-uniform sparse array.

2. The wide-angle scanning optical phased array according to claim 1, wherein: A coupling gap (513) is provided between the photonic crystal grating (512) and the main channel waveguide (511); The coupling gap is 220nm-255nm.

3. The wide-angle scanning optical phased array according to claim 1, wherein: The radius of the photonic crystal (512b) is 75nm-100nm; the lattice constant of the photonic crystal (512b) is 450nm-500nm.

4. The wide-angle scanning optical phased array according to any one of claims 1 to 3, characterized in that: The laser (1) comprises at least two groups of broadband tunable lasers connected in series.

5. The wide-angle scanning optical phased array according to claim 4, characterized in that: The beam splitting network (2) includes a multi-stage Y-type beam splitter, a multi-mode interference beam splitter or a star-type coupling beam splitter.

6. The wide-angle scanning optical phased array according to claim 4, characterized in that: The optical amplifier array (3) is arranged in each branch of the beam splitting network (2).

7. The wide-angle scanning optical phased array according to claim 4, characterized in that: The phase shifter array (4) includes a silicon-based electro-optical phase shifter, a thermo-optical phase shifter or a III-V MOS phase shifter.

8. The wide-angle scanning optical phased array according to claim 1, wherein: The laser (1), beam splitting network (2), optical amplifier array (3), phase shifter array (4) and antenna array (5) are all made of III-V group materials and are heterogeneously integrated into a single chip.

9. A laser radar, characterized in that: The invention comprises an optical phased array for wide-angle scanning as described in any one of claims 1 to 8.

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