Integrated distributed aperture OPA array common phase system based on inter-chip phase measurement

Abstract

The present invention discloses an integrated distributed aperture OPA array common phase system based on inter-chip phase measurement, which belongs to the field of optical chips. It includes multiple integrated optical chips, optical switches, optical interconnect waveguides, on-chip amplifiers, directional couplers, on-chip phase modulators, silicon-based optical mixers, and OPA modules. The laser output by the laser generating device enters the integrated optical chip through a coupler and is divided into three paths through an optical switch; the first and third laser paths enter the adjacent integrated optical chip through an optical interconnect waveguide; the second laser path passes through three identical directional couplers connected in series after passing through an on-chip optical amplifier; the three directional couplers couple part of the laser to the silicon-based optical mixer and the optical interconnect waveguide of the adjacent optical chip respectively. The lasers between different optical chips are coupled into the mixer for measurement through the optical interconnect waveguide and the results are coupled to the outside of the chip for processing. The common phase between adjacent optical chips is achieved through the on-chip phase modulator, and finally the common phase between all optical chips is achieved in sequence.

Description

Technical Field

[0001] The present invention relates to the field of optical chips, and in particular to an integrated distributed aperture OPA array common phase system based on inter-chip phase measurement. Background Art

[0002] The integrated photonics laser phased array (PIC-OPA) combines integrated optoelectronics technology with optical phased array (OPA) technology and is widely used in optical communications, lidar, quantum information processing and other fields. Its structure includes core components such as waveguides, phase shifters, and grating couplers. It transmits signals through optical waveguides and uses thermo-optical or electro-optical phase shifters based on carrier dispersion effects for phase modulation. In recent years, the MOABB project has developed modular optical lidars through planar photonic components, using electrically addressed phase modulators to accurately control the directionality of the light beam, and promoting the development of all-solid-state lidars.

[0003] However, existing integrated photonics OPAs face the problem of limited power output and array size. Due to the limited power carrying capacity of a single waveguide, the emission power and aperture of a single OPA are difficult to meet the requirements of long-distance detection and high precision. The existing silicon-based process and optical waveguide structure result in a small effective emission aperture of the OPA array, which restricts the detection distance and accuracy of the system. Due to the limitations of waveguide spacing, coupling effects between adjacent array elements, and on-chip losses, current integrated OPAs are difficult to achieve ideal performance in long-distance detection and high-power applications.

[0004] To overcome these bottlenecks, integrating multiple OPA chips into a wafer-scale on-chip OPA array has become an effective solution. By integrating a multi-aperture OPA array on a chip, the overall emission aperture and output power can be significantly improved, the long-range detection capability can be enhanced, and the detection accuracy can be improved. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the embodiment of the present invention provides an integrated distributed aperture OPA array common phase system based on inter-chip phase measurement, which solves the problems of insufficient optical aperture and insufficient output power of the existing OPA by integrating multiple OPA chips into an on-chip OPA array at the wafer level;

[0006] According to one aspect of the present invention, there is provided an integrated distributed aperture OPA array common phase system based on inter-chip phase measurement, comprising a plurality of integrated optical chips, optical switches, optical interconnect waveguides, on-chip amplifiers, directional couplers, on-chip phase modulators, silicon-based optical mixers, and OPA modules;

[0007] The number of the integrated optical chips is N, each of which includes an optical switch, an optical interconnect waveguide, an on-chip amplifier, a directional coupler, an on-chip phase modulator, a silicon-based optical mixer, and an OPA module; the light source output by the off-chip laser generating device enters the integrated optical chip through the coupler and then enters the input end of the 2×3 optical switch, and is divided into three paths through the optical switch; the first laser path enters the adjacent integrated optical chip on the right through the optical interconnect waveguide at the edge of the integrated optical chip, and serves as one of the input light sources of the optical chip; the third laser path enters the adjacent integrated optical chip below through the optical interconnect waveguide at the edge of the integrated optical chip, and serves as one of the input light sources of the optical chip; the second laser path passes through the on-chip amplifier and then passes through three identical directional couplers in sequence, and the directional coupler will separate part of the laser light and input it into the silicon-based optical mixer together with part of the laser light of the adjacent integrated optical chip. After the mixer output is transmitted to the outside of the chip for processing through the coupler, the control signal is output through the feedback system to control the on-chip phase modulator to achieve the common phase of the optical paths of the adjacent integrated optical chips; the second laser path is input to the OPA module after passing through the on-chip modulator, and is emitted to the free space through structures such as grating antennas;

[0008] Wherein N is an integer greater than or equal to 2;

[0009] Furthermore, the optical switch is based on the principle of multi-mode interference, and includes two input waveguides, three output waveguides and a multi-mode waveguide area; the multi-mode waveguide area has a refractive index change area, which can be operated independently or simultaneously; the refractive index change area can be a carrier injection area controlled by an external forward bias, or a region where the refractive index of the material is changed by external factors such as thermo-optical effect and acousto-optical effect;

[0010] Furthermore, the optical switch can output the optical signal input from any port from the three output ports respectively, or simultaneously from the three output ports; the optical switch can control the power ratio output from the three output ports;

[0011] Further, the optical interconnection waveguide includes a waveguide for interconnecting an integrated optical chip with an off-chip light source and a waveguide for optically interconnecting adjacent integrated optical chips;

[0012] Furthermore, the waveguide for interconnecting the integrated optical chip with the off-chip light source comprises an end coupler and a straight waveguide; the end coupler couples the off-chip light source from the optical fiber into the straight waveguide;

[0013] Furthermore, the waveguide for optically interconnecting adjacent integrated optical chips is composed of a straight waveguide and a gradually widened trapezoidal waveguide;

[0014] Furthermore, the number of the on-chip amplifiers is N, one of which is distributed on each integrated optical chip, and is used to amplify the power of the light beam in the waveguide;

[0015] Wherein N is an integer greater than or equal to 2;

[0016] Furthermore, the number of the directional couplers is 3N, and three directional couplers are sequentially distributed on the same optical path of each integrated optical chip; the first directional coupler separates a portion of the energy in the optical path and inputs it to the adjacent integrated optical chip above through the optical interconnection waveguide above the optical chip; the second directional coupler separates a portion of the energy in the optical path and inputs it to the silicon-based optical mixer on the chip; the third directional coupler separates a portion of the energy in the optical path and inputs it to the adjacent integrated optical chip on the right through the optical interconnection waveguide on the right side of the optical chip;

[0017] Wherein N is an integer greater than or equal to 2;

[0018] Furthermore, the number of the on-chip phase modulators is N, one of which is distributed on each integrated optical chip; the phase modulator receives an off-chip control signal to modulate the phase of the optical path so that two adjacent integrated optical chips are phase-locked;

[0019] Wherein N is an integer greater than or equal to 2;

[0020] Furthermore, the silicon-based optical mixer has two input ends, which are respectively connected to the weak light beams coupled by the directional coupler from two adjacent optical paths; the silicon-based optical mixer is connected to the off-chip phase measurement detection module through the optical fiber-waveguide coupler, and the phase error between the two adjacent paths can be extracted by the homodyne detection method;

[0021] Furthermore, the silicon-based optical mixer may be an optical mixer based on a 3dB coupler and a phase shifter, or an optical mixer based on a multimode interference coupler;

[0022] Furthermore, the number of the OPA modules is N, one of which is distributed on each integrated optical chip, and has the function of emitting laser into free space and scanning within a certain angle range;

[0023] Furthermore, the common phase realization mode of the integrated optical chip array is that, starting from the second column, all optical chips realize common phase with the adjacent integrated optical chip on the left through optical interconnection waveguides and silicon-based optical mixers; in the first column of the optical chip array, all optical chips realize common phase with the adjacent integrated optical chips below and on the right at the same time through optical interconnection waveguides and silicon-based optical mixers; and so on, ultimately achieving common phase of the entire optical chip array.

[0024] Beneficial effects of the present invention: The present invention integrates multiple OPA chips into an on-chip OPA array of wafer level. By integrating a multi-aperture OPA array on-chip, the overall emission aperture and output power can be significantly improved, the long-distance detection capability can be enhanced, and the detection accuracy can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the principle of an integrated optical chip provided by an embodiment of the present invention.

[0026] Figure 2 A schematic diagram of the principle of an integrated distributed aperture OPA array common phase system based on inter-chip phase measurement provided in an embodiment of the present invention.

[0027] Figure 3 A schematic diagram of the principle of an end face coupler provided in an embodiment of the present invention.

[0028] Figure 4 A top view of an optical interconnect waveguide structure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0031] Figure 1 A schematic diagram of an integrated optical chip provided by an embodiment of the present invention, referring to Figure 1 The integrated optical chip includes an optical switch 10, an on-chip amplifier 20, a first directional coupler 30-a third directional coupler 32, an on-chip phase modulator 40, an OPA module 50, a silicon-based optical mixer 60, and a first optical interconnect waveguide 70-a sixth optical interconnect waveguide 75; Figure 1The waveguide arrangement in the figure is schematic and does not limit the embodiments of the present invention. The light source output by the off-chip laser generating device enters the integrated optical chip through the coupler and then enters the input end of the 2×3 optical switch 10, and is divided into three paths through the optical switch 10. The first laser path enters the adjacent integrated optical chip on the right through the fifth optical interconnect waveguide 74 at the edge of the integrated optical chip, and serves as one of the input light sources of the adjacent integrated optical chip on the right. The third laser path enters the adjacent integrated optical chip below through the second optical interconnect waveguide 71 passing through the edge of the integrated optical chip, and serves as one of the input light sources of the adjacent integrated optical chip below. The second laser path passes through the on-chip amplifier 20 and then passes through three identical first directional couplers 30-third directional couplers 32 in sequence. The first directional coupler 30 A portion of the energy in the optical path is separated and input into the adjacent integrated optical chip above through the sixth optical interconnect waveguide 75 above the integrated optical chip; the second directional coupler 31 separates a portion of the energy in the optical path and inputs it into the silicon-based optical mixer 60 on the chip. The output of the silicon-based optical mixer 60 is transmitted to the outside of the chip through the seventh optical interconnect waveguide 76 for processing, and then the control signal is output through the feedback system to control the on-chip phase modulator 40 to achieve the common phase of the optical paths of adjacent integrated optical chips; the third directional coupler 32 separates a portion of the energy in the optical path and inputs it into the adjacent integrated optical chip on the right through the third optical interconnect waveguide 72 on the right side of the integrated optical chip; the second laser is input into the OPA module 50 after passing through the on-chip phase modulator 40, and is emitted into the free space through structures such as grating antennas;

[0032] The laser generating device may be a separate laser device coupled to the chip using a fiber-waveguide coupler or an edge coupler, or may be a single-wavelength distributed Bragg feedback laser. In a specific implementation, it may be a laser chip integrated with other on-chip structures in the embodiment on the same chip.

[0033] Wherein, the on-chip phase modulator may be a thin-film lithium niobate phase modulator or a silicon waveguide phase modulator;

[0034] For example, Figure 2 A schematic diagram of the principle of an integrated distributed aperture OPA array common phase system based on inter-chip phase measurement provided by an embodiment of the present invention; Figure 2 Four integrated optical chips are schematically selected to form an optical chip array; Figure 2After the off-chip laser output device enters the first integrated optical chip 100, it is divided into three optical paths by the optical switch 101; the first optical path is output to the second integrated optical chip 200 through the optical interconnect waveguide 110, and is input into the optical switch 201 as a light source; the second laser passes through the on-chip amplifier and then passes through three identical directional couplers in sequence, and the second directional coupler 104 in the first integrated optical chip 100 separates a part of the energy in the optical path and inputs it into the silicon-based optical mixer 108 in the first integrated optical chip 100 on the chip. At the same time, another input of the silicon-based optical mixer 108 in the first integrated optical chip 100 comes from the first directional coupler 303 in the third integrated optical chip 300 below, and is input into the silicon-based optical mixer 108 in the first integrated optical chip 100 through the optical interconnect waveguide 109; the output of the silicon-based optical mixer 108 in the first integrated optical chip 100 is transmitted to the off-chip for processing through the optical interconnect waveguide, and then the control signal is output through the feedback system to control the on-chip regulation in the first integrated optical chip 100. Phase modulator 106 is used to realize the common phase of the optical path between the first integrated optical chip 100 and the third integrated optical chip 300; the third directional coupler 105 in the first integrated optical chip 100 separates part of the energy in the optical path, and enters the silicon-based optical mixer 208 in the second integrated optical chip 200 through the optical interconnect waveguide 112. The other input of the silicon-based optical mixer comes from the second directional coupler 204 in the second integrated optical chip 200. The output signal of the silicon-based optical mixer 208 in the second integrated optical chip 200 enters the first integrated optical chip 100 through the optical interconnect waveguide 111, and then outputs it to the outside of the chip through the end coupler for processing. The control signal is output through the feedback system to control the on-chip phase modulator 106 in the first integrated optical chip 100, so as to realize the common phase of the optical path between the first integrated optical chip 100 and the second integrated optical chip 200; the third integrated optical chip 300 and the fourth integrated optical chip 400 realize the common phase between the optical paths in the same way, and so on to realize the common phase of the entire optical chip array;

[0035] The silicon-based optical mixer may be an optical mixer based on a 3dB coupler and a phase shifter, or an optical mixer based on a multimode interference coupler;

[0036] Optionally, the optical switch is based on the principle of multi-mode interference, and includes two input waveguides, three output waveguides and a multi-mode waveguide area; the multi-mode waveguide area has a refractive index change area, which can be operated independently or simultaneously; the refractive index change area can be a carrier injection area controlled by an external forward bias, or a area where the refractive index of the material is changed by external factors such as thermo-optical effect and acousto-optical effect;

[0037] Optionally, the optical switch can output the optical signal input from any port from three output ports respectively, or output it from three output ports simultaneously; the optical switch can control the power ratio output from the three output ports.

[0038] Figure 3 A schematic diagram of the principle of an end coupler provided by an embodiment of the present invention; Figure 3 Optionally, the end coupler includes a wedge-shaped waveguide and a straight waveguide, which are used to input off-chip optical signals into the chip as a light source and transmit on-chip optical signals to the outside of the chip for processing.

[0039] Figure 4 A top view of an optical interconnect waveguide structure provided by an embodiment of the present invention; Figure 4 Optionally, the optical interconnect waveguide includes a section of trapezoidal waveguide, which can increase the transmitted optical power.

[0040] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An integrated distributed aperture OPA array common phase system based on inter-chip phase measurement, characterized in that: The system includes a plurality of integrated optical chips arranged adjacent to each other, each integrated optical chip including an optical switch, an optical interconnect waveguide, an on-chip amplifier, a directional coupler, an on-chip phase modulator, a silicon-based optical mixer and an OPA module; an input laser light source entering the integrated optical chip is divided into three paths by the optical switch; Two of the laser beams enter the adjacent integrated optical chips on the right and bottom sides through the optical interconnect waveguides at the edge of the integrated optical chip, and serve as one of the input laser light sources of the corresponding integrated optical chip; After the last laser passes through the on-chip amplifier, part of the laser is separated based on the directional coupler. The silicon-based optical mixer in the first column of integrated optical chips receives part of the laser separated by the directional coupler on the chip and the directional coupler in the adjacent integrated optical chip on the lower side. The silicon-based optical mixer in the integrated optical chip starting from the second column receives part of the laser separated by the directional coupler on the chip and the directional coupler in the adjacent integrated optical chip on the left. After the on-chip silicon-based optical mixer outputs to the outside for processing, the control signal is output through the feedback system to control the on-chip phase modulator to achieve the common phase of the optical paths of adjacent integrated optical chips; the laser after passing through the on-chip phase modulator is input to the OPA module and emitted into free space.

2. The integrated distributed aperture OPA array common phase system based on inter-chip phase measurement according to claim 1 is characterized in that: The optical switch is based on the principle of multi-mode interference, and includes two input waveguides, three output waveguides and a multi-mode waveguide area; the multi-mode waveguide area has a refractive index change area that operates independently or simultaneously; the refractive index change area is a carrier injection area controlled by an external forward bias, or a region where the refractive index of a material is changed by external factors such as thermo-optical effect and acousto-optical effect.

3. The integrated distributed aperture OPA array common phase system based on inter-chip phase measurement according to claim 1 is characterized in that: The optical switch outputs the optical signal input from any port from three output ports respectively, or outputs from three output ports simultaneously; the optical switch controls the power ratio output from the three output ports.

4. The integrated distributed aperture OPA array common phase system based on inter-chip phase measurement according to claim 1 is characterized in that: The optical interconnection waveguide includes a waveguide for interconnecting an integrated optical chip with an off-chip light source and a waveguide for optically interconnecting adjacent integrated optical chips; the waveguide for interconnecting the integrated optical chip with the off-chip light source includes an end coupler and a straight waveguide; the end coupler couples the off-chip light source from the optical fiber to the straight waveguide; the waveguide for optically interconnecting adjacent integrated optical chips is composed of a straight waveguide and a gradually widened trapezoidal waveguide.

5. The integrated distributed aperture OPA array common phase system based on inter-chip phase measurement according to claim 1 is characterized in that: An on-chip amplifier is distributed on each integrated optical chip to amplify the power of the light beam in the waveguide.

6. The integrated distributed aperture OPA array common phase system based on inter-chip phase measurement according to claim 1 is characterized in that: Three directional couplers are sequentially distributed in the first column of integrated optical chips in the common phase system. The first directional coupler separates a portion of the energy in the optical path and inputs it into the silicon-based optical mixer of the adjacent integrated optical chip above through the optical interconnect waveguide above the optical chip. The second directional coupler separates part of the energy in the optical path and inputs it into the silicon-based optical mixer on the chip; the third directional coupler separates part of the energy in the optical path and inputs it into the silicon-based optical mixer of the adjacent integrated optical chip on the right through the optical interconnect waveguide on the right side of the optical chip.

7. The integrated distributed aperture OPA array common phase system based on inter-chip phase measurement according to claim 1 is characterized in that: Each integrated optical chip is distributed with an on-chip phase modulator; the on-chip phase modulator receives an off-chip control signal to modulate the phase of the optical path so that two adjacent integrated optical chips are phase-locked.

8. The integrated distributed aperture OPA array common phase system based on inter-chip phase measurement according to claim 1 is characterized in that: The silicon-based optical mixer has two input ends, which are respectively connected to the weak light beams coupled by the directional coupler of the optical routes of two adjacent integrated optical chips; the silicon-based optical mixer is connected to the off-chip phase measurement detection module through the optical fiber-waveguide coupler, and the phase error between the two adjacent routes is extracted by the homodyne detection method; and the control signal is output through the feedback system to control the on-chip phase modulator.

9. The integrated distributed aperture OPA array common phase system based on inter-chip phase measurement according to claim 1 is characterized in that: An OPA module is distributed on each integrated optical chip, which has the function of emitting laser into free space and scanning within a set angle range.

10. The integrated distributed aperture OPA array common phase system based on inter-chip phase measurement according to claim 1, characterized in that: An array of multiple integrated optical chips is formed, and the common phase realization mode is that starting from the second column, all integrated optical chips realize common phase with the adjacent integrated optical chips on their left through optical interconnection waveguides and silicon-based optical mixers; in the first column of the optical chip array, all optical chips realize common phase with the adjacent integrated optical chips below and on the right at the same time through optical interconnection waveguides and silicon-based optical mixers; and so on, eventually achieving common phase of the entire optical chip array.

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