Multi-light source OPA common phase system based on on-chip phase measurement

Abstract

The present invention discloses a multi-light source OPA co-phase system based on on-chip phase measurement, which belongs to the field of optical chips. It includes a laser generator, a fiber-waveguide coupler, an on-chip phase modulator, a directional coupler, a silicon-based optical mixer, an OPA module and a phase compensation module; the output ends of N parallel laser generators are connected to the fiber-waveguide coupler through optical fibers to enter the chip; a small part of the energy of two adjacent light beams is split by a directional coupler to enter the silicon-based optical mixer; the mixer outputs a signal to the phase compensation module outside the chip, performs subsequent DSP processing to obtain the phase difference between the two adjacent light beams, and outputs a control signal to the on-chip phase modulator, so that the two adjacent light beams are phase-locked; the above operations are performed on N light beams in sequence to achieve the co-phase of multiple light sources on the chip. By introducing a multi-light source co-phase system, the present invention optimizes the OPA power limitation problem caused by the limited transmission power of a single waveguide, and can greatly improve the OPA output power.

Description

Technical Field

[0001] The present invention relates to the field of optical chips, and in particular to a multi-light source OPA common phase system based on on-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, sensing and other fields. Its core architecture includes components such as optical waveguides, phase shifters, and grating couplers, and uses thermo-optical or electro-optical phase shifters based on carrier dispersion effects to control the phase of optical signals. The MOABB project builds optical lidars through planar photonic components, and uses electrically addressed phase modulators to achieve efficient pointing control of the light beam, promoting the miniaturization and modularization of all-solid-state lidars.

[0003] However, the main technical bottlenecks of the current integrated photonics laser phased array are concentrated on the limitations of output power and array size. The optical power that a single waveguide can withstand in an on-chip photonic chip is limited, making it difficult to support high-power optical phased array systems. The output power of the optical phased array is crucial to its applications such as long-distance detection, laser communications, and high-precision sensing. Limited by chip processing and material properties, the existing silicon-based waveguides have large losses and limited input optical power, which directly affects the overall output performance and range of the OPA. In addition, due to the limitations of waveguide spacing and array arrangement, the effective optical emission aperture of the current on-chip OPA is small and cannot meet the needs of long-distance applications. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, an embodiment of the present invention provides a multi-light source OPA common phase system based on on-chip phase measurement, which utilizes optoelectronic monolithic integration technology to complete the phase locking between the optical paths of multiple light sources on the chip, thereby solving the problem that the output power of the existing integrated optical chip OPA is limited by the waveguide power limitation.

[0005] According to one aspect of the present invention, a multi-light source OPA common phase system based on on-chip phase measurement is provided, comprising a plurality of laser generating devices, a fiber-waveguide coupler and an OPA module, and an on-chip amplifier, an on-chip phase modulator and a directional coupler on each laser optical path, and a silicon-based optical mixer and a phase compensation module are shared between two adjacent laser optical paths;

[0006] The laser light paths of two adjacent laser generating devices pass through the fiber-waveguide coupler, on-chip amplifier, on-chip phase modulator and two directional couplers in sequence. Most of the laser light enters the OPA module and is emitted into the free space. The remaining small part of the light of the two adjacent light paths is coupled to the silicon-based optical mixer, which transmits the optical signal to the off-chip phase compensation module through the fiber-waveguide coupler. After calculation by the phase-locking algorithm, the control signals are output to the on-chip phase modulators of the two adjacent light paths respectively, so as to realize the locking of the dynamic phase error of the two adjacent light paths.

[0007] Furthermore, an on-chip amplifier, an on-chip phase modulator, a directional coupler, a silicon-based optical mixer and an OPA module form an integrated optical chip; a total of N identical laser generating device optical paths are connected in parallel to the integrated optical chip through an optical fiber waveguide coupler, and the laser output by each laser generating device has the same power and frequency;

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

[0009] Furthermore, the input end of the fiber-waveguide coupler includes N laser generating devices outside the chip and 4 (N-1) silicon-based optical mixer output waveguides inside the chip; the output end includes N laser optical paths inside the chip and 4 (N-1) optical fiber ports corresponding to the silicon-based optical mixers outside the chip;

[0010] Wherein N is an integer greater than or equal to 2.

[0011] Furthermore, the number of the directional couplers is 2N, and two are sequentially distributed in each light beam; wherein the first directional coupler couples a portion of the energy in the light path to a silicon-based optical mixer shared by adjacent light paths on one side, and the second directional coupler couples a portion of the energy in the light path to an optical mixer shared by adjacent light paths on the other side;

[0012] Wherein N is an integer greater than or equal to 2.

[0013] Furthermore, the power proportion of the output port of the directional coupler coupled to the silicon-based optical mixer is smaller than the power proportion coupled to the OPA module.

[0014] Furthermore, the power distribution ratio of the output port of the directional coupler coupled to the silicon-based optical mixer and the OPA module is 1:99, or can be any ratio; the power proportion coupled to the optical mixer is smaller than the power proportion coupled to the OPA module.

[0015] Furthermore, the silicon-based optical mixer has two input ends, which are respectively connected to the weak light beams coupled by the directional coupler of two adjacent optical routes; the silicon-based optical mixer has four output ends, which are 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.

[0016] Furthermore, the silicon-based optical mixer is an optical mixer based on a 3dB coupler and a phase shifter, or an optical mixer based on a multi-mode interference coupler.

[0017] Furthermore, the on-chip phase modulator may be a thin-film lithium niobate phase modulator or a silicon waveguide phase modulator.

[0018] Furthermore, the OPA module has N optical input channels corresponding to the light beams output by N laser generating devices; the OPA module evenly distributes the energy of the N optical input channels to all transmitting antenna gratings through a tree-shaped MMI structure;

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

[0020] Furthermore, the phase compensation module receives the output signal from the on-chip optical mixer, and obtains the phase difference between adjacent optical paths after DSP processing; the phase compensation module adopts a phase-locking algorithm such as a PID control algorithm, a dithering method, a particle swarm algorithm or an SPGD algorithm, and generates a corresponding control signal which is loaded into the on-chip phase modulator to compensate for the dynamic phase error caused by the laser generating device between adjacent optical paths, thereby achieving phase locking between two adjacent optical paths, and each light beam is phase-locked with its adjacent light beam respectively, thereby achieving phase locking of all optical paths.

[0021] The phase compensation module includes an algorithm control unit, a photodetector, a digital-to-analog converter, and an analog-to-digital converter; the photodetector converts the received output optical signal of the on-chip silicon-based optical mixer into an electrical signal; the electrical signal output by the photodetector is converted into a digital signal by the analog-to-digital converter and transmitted to the algorithm control unit; the algorithm control unit uses a phase-locking algorithm such as a PID control algorithm, a dithering method, a particle swarm algorithm, or an SPGD algorithm to output a feedback control signal to the digital-to-analog converter; the digital-to-analog converter outputs a control signal in the form of an analog voltage to the on-chip phase modulator to achieve on-chip phase locking.

[0022] Beneficial effects of the present invention: The present invention significantly improves the output power of the integrated optical laser phased array (OPA) optical chip by adding multiple light sources. Specifically, by performing inter-chip phase measurement between on-chip OPAs and co-phase control of different OPAs integrated on the same wafer, the inconsistency between different OPAs caused by dynamic phase errors can be eliminated. This co-phase control achieves phase synchronization between light sources, allowing multiple OPAs to be coherently synthesized in the far-field region, thereby improving the overall output power of the system. In addition, coherent synthesis also reduces the main lobe width and improves the resolution of the system, thereby enhancing the system's long-distance detection and high-precision sensing capabilities. This technology effectively solves the problems of insufficient power and insufficient resolution caused by waveguide power limitations and limited array size in the prior art, thereby improving the performance of integrated photonics laser phased arrays and expanding its application potential in the fields of lidar, laser communications, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the principle of a multi-light source OPA common phase system based on on-chip phase measurement provided in an embodiment of the present invention.

[0024] Figure 2 A schematic diagram of the principle of a silicon-based optical mixer provided in an embodiment of the present invention.

[0025] Figure 3 A schematic diagram of the principle of an OPA module provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] Figure 1 A schematic diagram of a multi-light source OPA common phase system based on on-chip phase measurement provided by an embodiment of the present invention, referring to Figure 1 The OPA common phase system includes a plurality of laser generating devices (a first laser generating device 100, a second laser generating device 101 and a third laser generating device 102), a fiber-waveguide coupler 200, a plurality of on-chip amplifiers (a first on-chip amplifier 300, a second on-chip amplifier 301, a third on-chip amplifier 302), a plurality of on-chip phase modulators (a first on-chip phase modulator 400, a second on-chip phase modulator 401, a third on-chip phase modulator 402), a plurality of directional couplers (a first directional coupler 500, a second directional coupler 501, a third directional coupler 502, a fourth directional coupler 503, a fifth directional coupler 504, a sixth directional coupler 505), a plurality of silicon-based optical mixers (a first silicon-based optical mixer 600, a second silicon-based optical mixer 601), an OPA module 700 and a plurality of phase compensation modules (a first phase compensation module 800, a second phase compensation module 801); Figure 1 Three laser generating devices are schematically taken as an example, which is not a limitation to the embodiments of the present invention;

[0029] The input end of the fiber-waveguide coupler 200 is used to receive single-wavelength lasers output by multiple laser generating devices, and the single-wavelength lasers enter the integrated optical chip through the fiber-waveguide coupler 200; taking the optical path where the first laser generating device 100 is located as an example, after entering the integrated optical chip, the laser passes through the first on-chip optical amplifier 300, the first on-chip phase modulator 400, the first directional coupler 500, and the fourth directional coupler 503 in sequence, wherein most of the light enters the OPA module 700 and is emitted into the free space, and the remaining small part of the light is coupled to one of the input ports of the first silicon-based optical mixer 600; similarly, the laser in the optical path where the second adjacent laser generating device 101 is located, after entering the integrated optical chip, passes through the second On-chip optical amplifier 301, second on-chip phase modulator 401, second directional coupler 501, fifth directional coupler 504, wherein most of the light enters OPA module 700 and is emitted into free space, and the remaining small part of the light is coupled to another input port of the first silicon-based optical mixer 600; the output port of the first silicon-based optical mixer 600 transmits the optical signal to the first phase compensation module 800 outside the chip through the optical fiber-waveguide coupler 200; the first phase compensation module 800 outputs control signals to the first on-chip phase modulator 400 and the second on-chip phase modulator 401 respectively after calculation by the phase-locking algorithm, so as to achieve locking of the dynamic phase errors of two adjacent paths; and so on to achieve the common phase of all on-chip optical paths;

[0030] 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.

[0031] Optionally, the phase compensation module includes an algorithm control unit, a photodetector, a digital-to-analog converter and an analog-to-digital converter; the photodetector converts the received output optical signal of the on-chip silicon-based optical mixer into an electrical signal; the electrical signal output by the photodetector is converted into a digital signal by the analog-to-digital converter and transmitted to the algorithm control unit; the algorithm control unit uses a phase-locking algorithm such as a PID control algorithm, a dithering method, a particle swarm algorithm or an SPGD algorithm to output a feedback control signal to the digital-to-analog converter; the digital-to-analog converter outputs a control signal in the form of an analog voltage to the on-chip phase modulator to achieve on-chip phase locking;

[0032] Wherein, the on-chip phase modulator may be a thin-film lithium niobate phase modulator or a silicon waveguide phase modulator;

[0033] For example, Figure 2A schematic diagram of the principle of a silicon-based optical mixer provided in an embodiment of the present invention; a 2×2 multimode interference coupler 20 is provided at two adjacent ports at the output end of a 2×4 multimode interference coupler 10; in an embodiment of the present invention, homodyne interference measurement can be performed on two adjacent lasers;

[0034] 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;

[0035] Figure 3 A schematic diagram of the principle of an OPA module provided in an embodiment of the present invention; comprising N tree-shaped multimode interference couplers 701, the output end of each tree-shaped multimode interference coupler is connected to a phase modulator 702 for controlling the phase difference between the OPA antennas to achieve scanning, and the phase modulator is connected to a grating antenna 703 for emitting a scanning beam; wherein N is an integer greater than or equal to 2, and the specific number is kept consistent with the number of laser generating devices, Figure 3 In the example, N=2 is used as an example, which is not a limitation of the embodiment of the present invention;

[0036] Optionally, in one embodiment of the present invention, the number of grating antennas 703 corresponding to a single tree-shaped multimode interference coupler 701 is at least 256; further, the number of grating antennas 703 corresponding to a single tree-shaped multimode interference coupler 701 is at least 1000;

[0037] 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. A multi-light source OPA common phase system based on on-chip phase measurement, characterized in that: It includes multiple laser generating devices, a fiber-waveguide coupler and OPA module, as well as an on-chip amplifier, an on-chip phase modulator and a directional coupler on each laser optical path. Two adjacent laser optical paths share a silicon-based optical mixer and phase compensation module. The laser light paths of two adjacent laser generating devices pass through the fiber-waveguide coupler, on-chip amplifier, on-chip phase modulator and two directional couplers in sequence. Most of the laser light enters the OPA module and is emitted into the free space. The remaining small part of the light of the two adjacent light paths is coupled to the silicon-based optical mixer, which transmits the optical signal to the off-chip phase compensation module through the fiber-waveguide coupler. After calculation by the phase-locking algorithm, the control signals are output to the on-chip phase modulators of the two adjacent light paths respectively, so as to realize the locking of the dynamic phase error of the two adjacent light paths.

2. The multi-light source OPA common phase system based on on-chip phase measurement according to claim 1, characterized in that: An on-chip amplifier, an on-chip phase modulator, a directional coupler, a silicon-based optical mixer and an OPA module form an integrated optical chip; a total of N identical laser generating device optical paths are connected in parallel to the integrated optical chip through an optical fiber waveguide coupler, and the laser output by each laser generating device has the same power and frequency; Wherein N is an integer greater than or equal to 2.

3. The multi-light source OPA common phase system based on on-chip phase measurement according to claim 1, characterized in that: The input end of the fiber-waveguide coupler includes N laser generating devices outside the chip and 4 (N-1) silicon-based optical mixer output waveguides inside the chip; the output end includes N laser optical paths inside the chip and 4 (N-1) optical fiber ports corresponding to the silicon-based optical mixers outside the chip; Wherein N is an integer greater than or equal to 2.

4. The multi-light source OPA common phase system based on on-chip phase measurement according to claim 1, characterized in that: The number of the directional couplers is 2N, and two are distributed in sequence for each light beam; the first directional coupler couples a portion of the energy in the light path to a silicon-based optical mixer shared by adjacent light paths on one side, and the second directional coupler couples a portion of the energy in the light path to an optical mixer shared by adjacent light paths on the other side; Wherein N is an integer greater than or equal to 2.

5. The multi-light source OPA common phase system based on on-chip phase measurement according to claim 1, characterized in that: The power proportion of the output port of the directional coupler coupled to the silicon-based optical mixer is smaller than the power proportion coupled to the OPA module.

6. The multi-light source OPA common phase system based on on-chip phase measurement according to claim 1, characterized in that: The power distribution ratio of the output port of the directional coupler coupled to the silicon-based optical mixer and the OPA module is 1:

99.

7. The multi-light source OPA common phase system based on on-chip phase measurement according to claim 1, 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 from two adjacent optical routes; the silicon-based optical mixer has four output ends, which are 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.

8. The multi-light source OPA common phase system based on on-chip phase measurement according to claim 1, characterized in that: The silicon-based optical mixer is an optical mixer based on a 3dB coupler and a phase shifter, or an optical mixer based on a multi-mode interference coupler.

9. The multi-light source OPA common phase system based on on-chip phase measurement according to claim 1, characterized in that: The OPA module has N optical input channels corresponding to the light beams output by N laser generating devices; The OPA module distributes the energy of N optical input channels evenly to all transmitting antenna gratings through a tree-shaped MMI structure; Wherein N is an integer greater than or equal to 2.

10. The multi-light source OPA common phase system based on on-chip phase measurement according to claim 1, characterized in that: The phase compensation module receives the output signal from the on-chip optical mixer, and obtains the phase difference between adjacent optical paths after DSP processing; the phase compensation module adopts a phase-locking algorithm such as a PID control algorithm, a dithering method, a particle swarm algorithm or an SPGD algorithm, and generates a corresponding control signal which is loaded into the on-chip phase modulator to compensate for the dynamic phase error caused by the laser generating device between adjacent optical paths, thereby achieving phase locking between two adjacent optical paths, and each light beam is phase-locked with its adjacent light beam respectively, thereby achieving phase locking of all optical paths.

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