An optical phased array with high output optical power

Abstract

The present invention discloses an optical phased array with high output optical power, which uses a two-stage structure to complete power splitting. The two-stage structure includes: a primary power splitting module for performing preliminary power splitting on the input coherent light; a secondary power splitting module for further splitting the split coherent light, and the secondary power splitting module and the phase modulation module are located on the same chip or prepared using the same process / material. The power splitting is realized by using a two-stage structure, firstly the primary power splitting module performs preliminary power splitting, and then the secondary power splitting module which is well compatible with the phase modulation module in production and manufacturing completes further power splitting. Compared with the existing solution, the phased array can support greater optical power, thereby improving the maximum working distance of the laser radar and the scanning ranging accuracy at a long distance.

Description

Technical Field

[0001] The invention relates to the field of optoelectronic technology, and in particular to an optical phased array with high output light power. Background Art

[0002] Optical phased array is a type of optoelectronic device that achieves directional emission, scanning or reception of light beams by regulating the phase between channels. It is usually composed of coherent light source, power splitter, phase modulation, light output and other units as well as optical connections between the units. Among them, the maximum output light power is one of the core indicators for measuring the performance of optical phased arrays. Furthermore, the main factors affecting the maximum output light power include: the maximum output power of the coherent light source unit, the maximum input power supported by the power splitter unit, the loss introduced by the phase modulation unit and the output efficiency of the light output unit.

[0003] At present, the technical problem of optical phased array is that the maximum output light power supported is low. One of the main reasons is that when the coherent light source unit works in a high-power output state, the structure of the power splitter unit close to the input end and the optical connection between the power splitter unit and the coherent light source unit are easily damaged reversibly or irreversibly due to photothermal effect and other reasons, causing performance degradation or even burning. Summary of the invention

[0004] In view of this, the present invention provides an optical phased array with high output light power to solve the technical problem that the maximum working distance and scanning accuracy of the current optical phased array are limited due to the low maximum output light power supported. In order to have a basic understanding of some aspects of the disclosed embodiments, a simple summary is given below. This summary is not a general review, nor is it intended to identify key / important components or describe the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a preface to the detailed description that follows.

[0005] The present invention adopts the following technical solution:

[0006] The present invention provides an optical phased array with high output optical power, which uses a two-stage architecture to complete power splitting. The two-stage architecture includes:

[0007] A primary power splitting module, used for performing preliminary power splitting on the input coherent light;

[0008] The secondary power splitting module is used to further split the coherent light after being split by the primary power splitting module, and the secondary power splitting module and the rear-end phase modulation module are located on the same chip or are manufactured using the same process / material.

[0009] Among them, when the phase modulation module is a chip-based on-chip modulator, the first-level power branching module is constructed by an optical fiber splitter, and the second-level power branching module is constructed by preparing an on-chip splitting structure by etching or doping on the chip.

[0010] Among them, when the phase modulation module is a silicon / lithium niobate / III-V modulator based on a silicon / lithium niobate / III-V chip, the PLC splitter is prepared by doping on the substrate, laser-induced change of the local refractive index or etching and growing an optical structure to construct the first-level power splitting module located on the PLC chip, and the second-level power splitting module is constructed on the silicon / lithium niobate / III-V chip through a silicon / lithium niobate / III-V splitting structure.

[0011] Among them, when the phase modulation module is a silicon modulator based on a silicon-silicon nitride chip, the first-level power branching module is constructed by using a silicon nitride splitter structure on the silicon-silicon nitride chip, and the second-level power branching module is constructed by using a silicon splitter structure on the silicon-silicon nitride chip.

[0012] Wherein, the optical phased array with high output optical power further includes: a connection module for connecting the primary power branching module with the secondary power branching module, and the connection module includes: a polarization management unit and / or a power management unit;

[0013] The polarization management unit is a polarization beam splitter or a polarization beam splitter rotator, and the polarization management unit inputs transverse magnetic or transverse electric polarized light into the secondary power splitting module, and guides other types of polarized light into a lossy waveguide or a photodetector;

[0014] or,

[0015] The polarization management unit is a polarization filter, and the polarization management unit only allows one type of polarized light to pass through the polarization filter and enter the secondary power splitting module;

[0016] The power management unit is a fixed optical attenuator, an adjustable optical attenuator or a directional coupler.

[0017] The number of the secondary power shunt module and the number of the phase modulation module are both at least one, and the secondary power shunt module and the phase modulation module are arranged alternately.

[0018] Among them, the input spacing of each port of the secondary power splitter module is 0.250mm or 0.127mm.

[0019] Wherein, a loop structure or a light detector is used to assist alignment between the primary power splitting module and the secondary power splitting module.

[0020] Among them, the optical phased array with high output light power also includes: a coherent light source module for generating the coherent light; the coherent light source module is composed of a single laser, or a component combination of a laser and an optical modulator or an optical amplifier, or an optical module further assembled from multiple single light sources or component combinations.

[0021] Among them, the optical phased array with high output light power also includes: a light output module; the phase modulation module modulates the phase of each light output by the secondary power branching module, and outputs the formed target space light beam through the light output module.

[0022] The beneficial effects brought by the present invention are as follows: power splitting is realized by a two-stage architecture, wherein the primary power splitting module performs preliminary power splitting, and then the secondary power splitting module which is well compatible with the phase modulation module in production and manufacturing completes further power splitting. Compared with the existing solutions, the present invention enables the phased array to support greater optical power, thereby improving the maximum working distance of the laser radar and the scanning ranging accuracy at long distances. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a structural schematic diagram of an optical phased array with high output light power of the present invention;

[0025] Figure 2 This is a schematic diagram of a first implementation structure of a primary power splitting module, a secondary power splitting module and a phase modulation module of the present invention;

[0026] Figure 3 It is a schematic diagram of a second implementation structure of the primary power splitting module, the secondary power splitting module and the phase modulation module of the present invention;

[0027] Figure 4 It is a schematic diagram of a third implementation structure of the primary power splitting module, the secondary power splitting module and the phase modulation module of the present invention;

[0028] Figure 5 It is a structural schematic diagram of the present invention when the secondary power splitting modules and the phase modulation modules are alternately arranged;

[0029] Figure 6 is a schematic structural diagram of a second connection module in one embodiment of the present invention;

[0030] Figure 7 is a schematic structural diagram of the second connection module of the present invention in another embodiment;

[0031] Figure 8 is a schematic structural diagram of the second connection module of the present invention in another embodiment;

[0032] Fig. 9 It is a schematic structural diagram of the second connection module of the present invention in another embodiment. DETAILED DESCRIPTION

[0033] The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be clear that the described embodiments are only part of the embodiments of the present invention, rather than 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 are within the scope of protection of the present invention.

[0034] like Figure 1 As shown, in some illustrative embodiments, the present invention provides an optical phased array with high output light power, which uses a two-level architecture to complete power splitting, and the two-layer power beam splitting architecture uses different materials and manufacturing systems to support high-power incident light.

[0035] The optical phased array includes: a coherent light source module 100, a primary power branching module 200, a secondary power branching module 300, a phase modulation module 400, and a light output module 500. The coherent light source module 100 generates coherent light, which is branched and phase-modulated by the primary power branching module 200, the secondary power branching module 300, and the phase modulation module 400, and then outputs a target light beam (light field) by the light output module 500.

[0036] The coherent light source module 100 is used to generate coherent light.

[0037] Specifically, the coherent light source module 100 can be composed of a single laser, including but not limited to semiconductor lasers, fiber lasers, and solid lasers, and the working wavelength of the laser is not limited; the coherent light source module 100 can also be a combination of components composed of a laser and an optical modulator or an optical amplifier, etc., and can output coherent light with specific performance indicators; the coherent light source module 100 can also be an optical module that is further composed of multiple of the above-mentioned single light sources or component combinations and can output one or more monochromatic or multi-color coherent lights.

[0038] The two-stage architecture includes: a primary power shunt module 200 and a secondary power shunt module 300 .

[0039] The primary power splitting module 200 is used to perform preliminary power splitting on the input coherent light to obtain several coherent lights with smaller optical powers. The secondary power splitting module 300 is used to further split the coherent light with smaller optical powers after being split by the primary power splitting module 200 to obtain multiple coherent lights with even smaller optical powers.

[0040] The primary power splitter module 200 can work stably under a relatively large input optical power. The relatively large input optical power mentioned here means that if a coherent light beam of the same optical power is directly injected into any input port of the secondary power splitter module 300, it may cause the reversible or irreversible performance degradation or even functional failure of the components in the secondary power splitter module 300. The secondary power splitter module 300 has good manufacturing compatibility with the subsequent phase modulation module 400, that is, the secondary power splitter module 300 and the subsequent phase modulation module 400 are located on the same chip or are prepared using the same process / material.

[0041] Since a coherent light source module 100 usually transmits coherent light only through a pair of output / input ports, when the coherent light source module 100 works in a high-power output state, the structure of the power splitting part close to the input end and the optical connection with the coherent light source module are easily damaged reversibly or irreversibly due to photothermal effect and other reasons, causing performance degradation or even burning. Therefore, the present invention adopts a power splitting module in the form of a two-stage structure to connect with the coherent light source module 100, thereby increasing the maximum input power supported by the power splitting module, thereby increasing the maximum output power of the optical phased array system.

[0042] At the same time, since the power splitting module is connected to the phase modulation module 400, it is also very important to ensure that the power splitting module and the phase modulation module 400 have good manufacturing compatibility for the practical application and productization of the optical phased array. In this embodiment, the secondary power splitting module 300 and the back-end phase modulation module 400 are located on the same chip or are prepared using the same process / material, so that there is no need to introduce additional connections, such as chip-to-chip connection or chip-to-optical fiber connection, thereby avoiding the situation where a large-scale optical phased array with hundreds to thousands of split paths needs to use hundreds or thousands of pairs of ports for connection, thereby reducing the chip area, ensuring the stability of the optical connection, and reducing the loss.

[0043] Furthermore, the secondary power splitter module 300 and the phase modulation module 400 have good manufacturing compatibility, that is, they are located on the same chip or manufactured using the same process / material. The implementation of this architecture can be based on but not limited to the following methods:

[0044] The first implementation method:

[0045] like Figure 2As shown, when the phase modulation module 400 is implemented by an on-chip modulator 401 based on a chip, the primary power splitting module 200 can be constructed by an optical fiber splitter 201 prepared by a method such as optical fiber fusion taper, and the secondary power splitting module 300 can be constructed by an on-chip light splitting structure 301 with light splitting function prepared on the chip by etching or doping. At this time, the secondary power splitting module 300 and the phase modulation module 400 are located on the same chip, and the primary power splitting module 200 is located on another chip.

[0046] The fiber beam splitter 201 is used to complete the first-level power splitting, which is a power splitting solution of "fiber + chip". Compared with the chip, the fiber device generally supports a larger input power. Figure 2 The implementation shown is compared to Figure 3 , Figure 4 The implementation shown in the figure, the input power that the first-level power splitter module can support is larger, and thus Figure 2 The implementation shown is the one that has the potential to support the most power among the three methods mentioned in this article.

[0047] The second implementation method:

[0048] like Figure 3 As shown, when the phase modulation module 400 is implemented based on the silicon / lithium niobate / III-V modulator 402 on the silicon / lithium niobate / III-V chip, a planar light waveguide circuit (PLC) splitter with a light splitting function can be prepared by doping, laser-induced change of the local refractive index or etching and growing an optical structure on a substrate (materials such as quartz, polymer, etc.), that is, a primary power splitting module 200 located on the PLC chip is constructed by a PLC splitter 202, and a secondary power splitting module 300 is constructed on the silicon / lithium niobate / III-V chip based on a silicon / lithium niobate / III-V splitting structure 302 such as a Y branch tree, a 1×2 or 2×2 multimode interferometer tree or a star coupler. At this time, the secondary power splitting module 300 and the phase modulation module 400 are located on the same chip, and the primary power splitting module 200 is located on another chip.

[0049] Figure 3 The implementation shown is a compromise solution of "chip + chip" for power splitting. The first-level power splitting module uses PLC chip, which has the advantages of small size and low cost compared with optical fiber devices, and the process is simpler and more mature than silicon-silicon nitride chip.

[0050] The third implementation method:

[0051] like Figure 4As shown, when the phase modulation module 400 is implemented based on a silicon modulator 403 on a silicon-silicon nitride chip, a first-level power branching module 200 can be constructed on the silicon-silicon nitride chip using silicon nitride as the material based on a Y-branch tree, a 1×2 or 2×2 multimode interferometer tree, or a star coupler and other silicon nitride splitting structures 203, and a second-level power branching module 300 can be constructed on the silicon-silicon nitride chip using silicon as the material based on a Y-branch tree, a 1×2 or 2×2 multimode interferometer tree, a star coupler and other silicon splitting structures 303.

[0052] Figure 4 In the implementation shown, the primary power splitter module and the secondary power splitter module are on the same chip. This is a power splitter-as-chip solution, which makes the phased array more potentially lightweight and low-cost, but has certain requirements for the process development of silicon-silicon nitride chips.

[0053] The phase modulation module 400 is used to perform phase modulation on each branched light. The module is composed of several modulators, including but not limited to various optical modulators based on the principles of thermo-optic modulation, electro-optic modulation, electro-absorption modulation, etc.

[0054] Since the phase modulation module 400 has good manufacturing compatibility with the secondary power splitter module 300, it can be used to replace Figure 1 Another possible implementation of the architecture shown is as follows Figure 5 As shown, the number of the secondary power shunt module 300 and the phase modulation module 400 is at least one, and the secondary power shunt module 300 and the phase modulation module 400 are arranged alternately. The secondary power shunt module 300 and the phase modulation module 400 are arranged alternately to form a secondary power shunt and phase modulation module 310 having both secondary power shunt and phase modulation functions, so as to replace Figure 1 The two-stage power module 300 and the phase modulation module 400 are independent of each other.

[0055] The relationship between the number N1 of optical input ports of the primary power splitting module 200, the number N2 of optical output ports of the primary power splitting module 200, and the number M of optical input ports of the secondary power splitting module 300 satisfies the following formula:

[0056] 2N1≥N2≥128N1;

[0057] 2N1≥M≥128N1.

[0058] Wherein, N1 is a positive integer; N2 is generally equal to M. Since when M is larger, under current technical conditions, too many optical interfaces will occupy a huge chip area and affect the stability of the optical connection, the values ​​of N2 and M are limited as above in this embodiment to ensure the working stability of the system. Under the premise of improving technical conditions, the values ​​of N2 and M can be larger in other optional embodiments based on the present invention.

[0059] The optical output module 500 is used to output light from the phased array to space. The optical output module 500 may be composed of antenna structures such as a plurality of one-dimensional grating couplers, fan-shaped grating couplers, Bragg gratings, chain-shaped etched waveguides, fishbone-shaped waveguides, and waveguide external scatterers that scatter light from a plane to space, or may be composed of optical structures such as a plurality of waveguide end faces, tapered waveguides, and inverted tapered waveguides that output light from the edge of a plane. In addition, the present embodiment does not limit the introduction of auxiliary structures or components such as detectors, absorption regions, and lenses at the rear end or upper end of the optical output module 500 for monitoring, anti-reflection, and adjusting light output performance.

[0060] Preferably, the input spacing of each port of the secondary power splitter module 300 is 0.250 mm or 0.127 mm to adapt to common optical connection design specifications and non-customized general-purpose optical devices; other port spacings can also be selected according to actual application requirements to adapt to specially customized optical devices.

[0061] The coherent light source module 100 generates coherent light, which is output to the primary power splitting module 200. After the primary power splitting module 200 performs preliminary power splitting, the coherent light is output to the secondary power splitting module 300 to complete further power splitting. After the splitting, each coherent light is output to the phase modulation module 400, the phase of each light is modulated, and the formed target space light beam is output by the light output module 500. The necessary optical connections between the modules are the first connection module 610, the second connection module 620, the third connection module 630 and the fourth connection module 640. Among them, the connection module used to connect the primary power splitting module 200 and the secondary power splitting module 300 is defined as the second connection module 620.

[0062] The first connection module 610 is an optical connection between the coherent light source module 100 and the primary power splitter module 200, and can be a single-mode fiber, a few-mode fiber, a multi-mode fiber, a polarization-maintaining fiber, a special fiber, or a fiber array; it can also be a package based on fiber-to-chip docking or a package based on chip-to-chip docking. In addition, it is allowed to introduce various optical components based on fiber structure, on-chip structure or spatial optical elements into the first connection module 610, such as a wavelength splitter, a polarization controller or a microlens.

[0063] The second connection module 620 is an optical connection between the primary power splitting module 200 and the secondary power splitting module 300 .

[0064] When the primary power splitter module 200 is composed of Figure 2 When the fiber optic beam splitter 201 is constructed, the second connection module 620 may be a fiber array structure and an edge coupler or a grating coupler aligned and packaged, or other fiber and chip connection structures.

[0065] When the primary power splitter module 200 is composed of Figure 3 When the PLC splitter 202 shown is constructed, the second connection module 620 can be directly packaged by the port docking end face coupler of the PLC splitter 202, or it can be packaged by a microlens array or an on-chip pitch / spot size converter, or other chip-to-chip connection structures.

[0066] When the primary power splitter module 200 is composed of Figure 4 When the silicon nitride light splitting structure 203 is constructed, the second connection module 620 may be a silicon nitride waveguide-silicon waveguide converter on a silicon-silicon nitride chip.

[0067] The packaging design of the second connection module 620 can be assisted in alignment by introducing a loop structure at the input end of the secondary power split module 300, or by setting a photodiode or avalanche diode or other optical detector at any input end, any sub-branch or any output end of the secondary power split module 300. After alignment, materials such as ultraviolet glue, quartz or resin cover plates can be used for ultraviolet curing and auxiliary fixation. After fixation is completed, thermal annealing and other methods can be used to eliminate the residual stress of the package.

[0068] The third connection module 630 and the fourth connection module 640 are optical connections between the secondary power splitting module 300 and the phase modulation module 400 and between the phase modulation module 400 and the light output module 500, respectively. The present invention does not impose any limitation on the connection forms.

[0069] This embodiment provides an optical phased array implementation scheme, which supports high optical power input through the primary power splitter module 200, and the secondary power splitter module 300 and the phase modulation module 400 have good manufacturing compatibility, support high power and high performance. In addition to the necessary optical connection between the two-stage splitter modules, optional components can be introduced to achieve power and polarization management.

[0070] In some optional embodiments, the second connection module 620 includes: a polarization management unit and / or a power management unit, that is, the polarization management unit can be introduced into the second connection module 620 alone, the power management unit can be introduced alone, or the polarization management unit and the power management unit can be introduced at the same time, in which case the two are in a parallel relationship and can complete their own functions independently, so as to realize the power and polarization control of the input light, and further improve the working efficiency of the phased array and the quality of the output light beam.

[0071] like Figure 6 As shown, the polarization management unit can be a polarization beam splitter or a polarization beam splitter rotator. At this time, the polarization management unit inputs transverse magnetic or transverse electric polarized light into the secondary power splitting module 300, and guides other types of polarized light into the lossy waveguide or optical detector.

[0072] like Figure 7 As shown, the polarization management unit may also be a polarization filter. In this case, the polarization management unit only allows one type of polarized light to pass through the polarization filter and enter the secondary power splitting module 300 .

[0073] like Figure 8 As shown, the power management unit may be a fixed optical attenuator or an adjustable optical attenuator.

[0074] like Fig. 9 As shown, the power management unit may also be a directional coupler and output a certain proportion of light into the light detector 702 .

[0075] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An optical phased array with high output optical power, characterized in that: A two-level architecture is used to complete power splitting, and the two-layer power beam splitting architecture uses different materials and manufacturing systems to support high-power incident. The two-level architecture includes: The primary power splitting module is used to perform preliminary power splitting on the input coherent light to obtain several beams of coherent light with smaller optical power; A secondary power splitting module, used for further splitting the coherent light split by the primary power splitting module to obtain multiple coherent lights with lower optical power, and the secondary power splitting module and the phase modulation module at the rear end are located on the same chip or are prepared by the same process / material; the phase modulation module is an on-chip modulator based on a chip, and the secondary power splitting module is constructed by etching or doping on the chip to prepare an on-chip light splitting structure; A power splitter module in a two-stage structure is connected to a coherent light source module to increase the maximum input power supported by the power splitter module, thereby increasing the maximum output power of the optical phased array system. When the phase modulation module is a silicon / lithium niobate / III-V modulator based on a silicon / lithium niobate / III-V chip, the PLC splitter is prepared by doping on the substrate, laser-induced change of the local refractive index or etching and growing an optical structure to construct the first-level power splitting module located on the PLC chip, and the second-level power splitting module is constructed on the silicon / lithium niobate / III-V chip through a silicon / lithium niobate / III-V splitting structure.

2. The optical phased array with high output light power according to claim 1, characterized in that: Also includes: A connection module for connecting the primary power splitting module with the secondary power splitting module, wherein the connection module comprises: a polarization management unit and / or a power management unit; The polarization management unit is a polarization beam splitter or a polarization beam splitter rotator, and the polarization management unit inputs transverse magnetic or transverse electric polarized light into the secondary power splitting module, and guides other types of polarized light into a lossy waveguide or a photodetector; or, The polarization management unit is a polarization filter, and the polarization management unit only allows one type of polarized light to pass through the polarization filter and enter the secondary power splitting module; The power management unit is a fixed optical attenuator, an adjustable optical attenuator or a directional coupler.

3. The optical phased array with high output light power according to claim 2, characterized in that: The number of the secondary power shunt module and the number of the phase modulation module are both at least one, and the secondary power shunt modules and the phase modulation modules are arranged alternately.

4. The optical phased array with high output light power according to claim 3, characterized in that: The input spacing of each port of the secondary power splitter module is 0.250 mm or 0.127 mm.

5. The optical phased array with high output light power according to claim 4, characterized in that: A loop structure or a light detector is used to assist alignment between the primary power splitting module and the secondary power splitting module.

6. The optical phased array with high output light power according to claim 5, characterized in that: Also includes: A coherent light source module is used to generate the coherent light; the coherent light source module is composed of a single laser, or a component combination of a laser and an optical modulator or an optical amplifier, or an optical module further assembled from multiple single light sources or component combinations.

7. The optical phased array with high output light power according to claim 6, characterized in that: Also includes: Optical output module; The phase modulation module modulates the phase of each light output by the secondary power splitter module, and outputs the formed target spatial light beam via the light output module.

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