Passive large-view-field silicon-based optical phased array

Abstract

The utility model discloses a passive large-view-field silicon-based optical phased array which comprises a silicon substrate, a silicon dioxide buried oxide layer and a silicon nitride layer. The silicon nitride layer comprises an inverted-cone-shaped coupling waveguide, an optical beam splitting module, a phase delay module and a waveguide grating antenna module, the inverted-cone-shaped coupling waveguide is used for coupling input light into the optical beam splitting module, and the optical beam splitting module is used for equally dividing an optical signal generated by the input light into N paths of sub optical signals with equal power, the phase delay module comprises an n-shaped waveguide array and a sine-type waveguide array, the n-shaped waveguide array is used for carrying out phase regulation and control on each path of sub-optical signals, the sine-type waveguide array is used for reducing waveguide spacing, and the waveguide grating antenna module is used for radiating light energy output by the sine-type waveguide array. According to the optical phased array, the phase does not need to be changed through electric tuning or thermal tuning, and meanwhile large-view-field scanning of the optical phased array can be achieved after the optical phased array passes through the sinusoidal waveguide array arranged compactly.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of optoelectronic devices, especially relates to a passive large field of view silicon-based optical phased array. BACKGROUND

[0002] Optical phased array (OPA) technology is a technique that uses an array of multiple optical units to adjust the direction of a light beam by controlling the phase difference between the optical units. Traditional phased array technology is applied in the field of electromagnetic waves, such as radar and communication systems. However, introducing this technology into the field of optics can achieve high-speed, precise, and mobile component-free beam control. The working principle of optical phased array is based on the interference effect of light waves: by adjusting the optical path difference or phase difference between the array units, different interference patterns are generated, thereby guiding the light beam to focus or scan in different directions. Compared with traditional mechanical scanning systems, the advantages of optical phased array are: it can complete the scanning of the light beam within nanoseconds or even shorter time; due to the short wavelength of light waves, optical phased array can control the light beam at very high spatial resolution; optical phased array has no movement of mechanical components, avoiding mechanical wear and tear, and improving the stability and life of the system.

[0003] Passive optical phased array technology controls the phase of light waves by introducing waveguide phase delay lines in each waveguide array in the array, rather than relying on external power or signal driving. At the micro-nano scale, light beam control is achieved by changing the optical path.

[0004] Optical phased array technology controls the propagation direction of light waves by adjusting the phase of array units, which makes it have very high precision and flexibility in beam scanning, beam pointing, etc. Achieving large-angle scanning (i.e. large field of view) is a key technical challenge for optical phased array, and the background of this technology involves multiple aspects, including phase control, array design, material selection, and the physical principles of beam propagation. SUMMARY

[0005] Therefore, it is necessary to provide a passive large field of view silicon-based optical phased array to solve the above technical problems, so as to obtain an optical phased array with small power consumption and capable of achieving large-angle scanning.

[0006] A passive large field of view silicon-based optical phased array comprises:

[0007] A silicon substrate;

[0008] A silicon dioxide buried oxygen layer is arranged on the upper surface of the silicon substrate;

[0009] A silicon nitride layer is arranged on an upper surface of the silicon dioxide buried oxide layer; the silicon nitride layer comprises an inverted taper coupling waveguide, an optical beam splitting module, a phase delay module and a waveguide grating antenna module, the inverted taper coupling waveguide is used to couple input light into the optical beam splitting module, the optical beam splitting module is used to equally divide optical signals generated by input light into N paths of sub-optical signals with equal power, the phase delay module comprises a herringbone waveguide array and a sinusoidal waveguide array, the herringbone waveguide array is used to phase control each path of sub-optical signals so that any two adjacent paths of sub-optical signals have the same phase difference, and the sinusoidal waveguide array is used to reduce waveguide spacing, and the waveguide grating antenna module is used to radiate optical energy output by the sinusoidal waveguide array, and N is greater than or equal to 2.

[0010] Optionally, the optical beam splitting module comprises a plurality of cascaded multimode interference couplers.

[0011] Optionally, the cascaded multimode coupler divides the power of the optical signal into two, the input is a rectangular silicon nitride waveguide, the middle multimode interference coupling region is a rectangular silicon nitride waveguide with a larger size, and the output is two rectangular silicon nitride waveguiders with the same size as the input, wherein the length of the rectangular silicon nitride waveguide is 20-28 μm.

[0012] Optionally, the herringbone waveguide array comprises N waveguides, wherein the lengths of the N waveguides are different.

[0013] Optionally, the sinusoidal waveguide array comprises N sinusoidal waveguides, wherein the spacing between any two adjacent sinusoidal waveguides is less than the wavelength length of the input light.

[0014] Optionally, the waveguide grating antenna module comprises N waveguide gratings.

[0015] Optionally, the optical beam splitting module, the phase delay module and the waveguide grating antenna module are connected to each other through silicon nitride waveguides to realize low-loss optical interconnection between different modules.

[0016] Optionally, the width of the silicon nitride waveguide ranges from 800 nm to 1000 nm.

[0017] Optionally, the height of the silicon substrate is greater than the height of the silicon dioxide buried oxide layer, and the height of the silicon dioxide buried oxide layer is greater than the height of the silicon nitride layer.

[0018] Optionally, the inverted taper coupling waveguide comprises a gradual change region and a stable region, the gradual change region is an input end away from one end of the stable region, and the size of the gradual change region gradually increases from the input end to the end of the gradual change region close to the stable region until the size of the gradual change region is the same as the size of the stable region.

[0019] Compared with the prior art, the application has the advantages that:

[0020] 1. The application utilizes a "few" type waveguide structure, which can make the phase difference between each adjacent branch the same through calculation, so that the two-dimensional scanning of the OPA can be realized without adding electricity to the optical phased array, thereby greatly reducing power consumption. In addition, the phase noise of the passive chip is very low, and the beam quality does not decrease. Moreover, the shape and length of the extension line can be flexibly designed to better meet the detection of the chip. Compared with the traditional electrically and thermally adjusted optical phased array, the structure greatly reduces the energy consumption, and the beam quality does not decrease.

[0021] 2. The application uses a sinusoidal waveguide structure, which greatly reduces the spacing between the waveguides and also suppresses the generation of crosstalk between the waveguides, greatly improves the scanning angle, and also reduces the sidelobe. The beam scanning field of view of the one-dimensional optical phased array is related to the spacing of the antenna elements, and the smaller the spacing between the elements, the larger the field of view. Based on the principle of refractive index mismatch, a sinusoidal bending structure is introduced to break the parity symmetry of the mode, so that the spacing between the silicon nitride waveguides can be reduced to below the wavelength, and the crosstalk between the waveguides is also below 20 dB. This greatly improves the scanning angle of the optical phased array on the silicon nitride platform, thereby obtaining a large field of view and high resolution.

[0022] 3. The application adopts cascading multiple MMIs for beam splitting, which can realize uniform light power for each path and has very low branch insertion loss. Therefore, the integration of multiple OPAs can be met, and the efficiency and consistency are improved.

[0023] 4. The application realizes passive large-angle scanning OPA, which still has high scalability on this basis, such as increasing the number of OPA channels, increasing the length of the extension line, further reducing the waveguide spacing, etc., thereby improving the resolution, scanning angle, and suppressing sidelobe generation of the OPA. And this scheme can also be applied to other platforms, such as SOI, gallium arsenide, etc.

[0024] 5. The application realizes passivation, and the passive optical phased array does not generate additional heat due to the operation of electronic elements when working, thereby avoiding the influence of heat accumulation on system performance. In high-precision optical applications, thermal effects often cause beam deviation or signal attenuation. Passive design does not require high-cost driving electronics and power management systems, which can significantly reduce system cost, especially for large-scale integrated applications. Combined with silicon nitride material and passive phased array technology, the overall system has more obvious advantages in optical performance, reliability, power consumption, and cost. For applications that require precise control, low power consumption, and long-term stability (such as satellite communication, laser radar, medical imaging, etc.), passive large-field-of-view silicon nitride optical phased array is a very promising choice.

[0025] 6.The application opens up new ways for the passive application of silicon-based optoelectronic devices.Silicon-based optoelectronics can achieve functions such as optical waveguide,interferometric device and phase modulation with integrated optical elements,thus expanding its boundaries in optical applications.This integration not only enables silicon-based optoelectronics to gain an advantage in traditional optical fields(such as laser,optical fiber communication,etc.),but also enables the silicon-based platform to challenge more optical applications and improve the performance and functionality of the overall system.

[0026] 7.The high refractive index and good optical properties of silicon nitride material,combined with the mature process of silicon-based optoelectronics,can promote more optical elements to be integrated into a single silicon-based platform.This integration not only reduces system complexity and improves stability,but also significantly reduces volume and weight.Silicon-based optoelectronic devices may further develop towards miniaturization,low power consumption and high integration,and be applied to more extensive fields such as mobile communication,unmanned driving,intelligent sensors,etc.

[0027] In summary,the application realizes passive phase change by using waveguide extension lines,and achieves the same phase difference between each adjacent waveguide by calculating the length of the extension line of each waveguide.The application introduces sinusoidal waveguides,which can maintain low crosstalk between waveguides even below the wavelength spacing,thus realizing OPA large-angle scanning and reducing the generation of sidelobes.Passive large-field-of-view optical phased array promotes the development of integrated,low-power and high-performance silicon-based optoelectronic devices,and provides a new technical path for multiple frontier technical fields such as optical communication,optical sensing,laser radar and quantum optics.This will accelerate the development of silicon-based optoelectronics towards higher performance and more extensive applications,and open up more possibilities. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiment or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to the structures shown in these drawings without creative labor.

[0029] Figure 1 is a top view of a passive large-field-of-view silicon-based optical phased array in an embodiment;

[0030] Figure 2 is a layered structure diagram of a passive large-field-of-view silicon-based optical phased array in an embodiment;

[0031] Figure 3 is a waveguide grating structure diagram of a passive large-field-of-view silicon-based optical phased array in an embodiment;

[0032] Figure 4Figure 1 is a schematic diagram of a reverse taper coupling waveguide structure of a passive large field-of-view silicon-based optical phased array in an embodiment.

[0033] 1, optical beam splitting module; 2, phase delay module; 21, several-shaped waveguide array; 22, sinusoidal waveguide array; 3, waveguide grating antenna module; 4, silicon nitride layer; 5, buried oxygen layer of silicon dioxide; 6, silicon substrate; 7, waveguide grating; 8, reverse taper coupling waveguide; 81, gradual change area; 82, stable area.

[0034] The realization, functional features and advantages of the utility model will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the utility model will be clearly and completely described with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.

[0036] It should be noted that all the directionality indications (such as up, down, left, right, front, back, etc.) in the embodiments of the utility model are only used to explain the relative position relationship, movement condition, etc. between the components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directionality indications also change accordingly.

[0037] In addition, the description of "first", "second" and the like in the utility model is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, "and / or" in the full text includes three schemes, taking A and / or B as an example, including A technical scheme, B technical scheme, and A and B simultaneously satisfying the technical scheme; in addition, the technical schemes of each embodiment can be combined with each other, but it must be based on the realization of the technical personnel in the art, when the combination of technical schemes appears contradictory or unachievable, it should be considered that the combination of technical schemes does not exist, and is not within the protection scope required by the utility model.

[0038] Reference Figure 1 and Figure 2The application provides a passive large-view-field silicon-based optical phased array, which comprises a silicon substrate 6, a silicon dioxide buried oxygen layer 5 and a silicon nitride layer 4, the silicon dioxide buried oxygen layer 5 is arranged on the upper surface of the silicon substrate 6, and the silicon nitride layer 4 is arranged on the upper surface of the silicon dioxide buried oxygen layer 5; the height of the silicon substrate 6 is greater than the height of the silicon dioxide buried oxygen layer 5, and the height of the silicon dioxide buried oxygen layer 5 is greater than the height of the silicon nitride layer 4.

[0039] In the embodiment, the height of the silicon substrate 6 is 500 μm, the height of the silicon dioxide buried oxygen layer 5 is 2 μm, the material of all components in the silicon nitride layer 4 is silicon nitride, the height of the waveguide structure in the silicon nitride is uniform, and the height of each component in the silicon nitride layer 4 is 0.5 μm.

[0040] Reference Figure 1 and Figure 4 The silicon nitride layer 4 comprises an inverted taper coupling waveguide 8, an optical beam splitting module 1, a phase delay module 2 and a waveguide grating antenna module 3, the inverted taper coupling waveguide 8 is used for coupling input light into the optical beam splitting module 1, the optical beam splitting module 1 is used for equally dividing optical signals generated by the input light into N sub-optical signals with equal power, the phase delay module 2 comprises a herringbone waveguide array 21 and a sinusoidal waveguide array 22, the herringbone waveguide array 21 is used for phase regulating each sub-optical signal, so that any two adjacent sub-optical signals have the same phase difference, the sinusoidal waveguide array 22 is used for reducing the waveguide spacing, the waveguide grating antenna module 3 is used for radiating optical energy output by the sinusoidal waveguide array 22, and N is greater than or equal to 2.

[0041] In the embodiment, N is 128.

[0042] The optical signal generated by the external laser source is coupled into the optical beam splitting module 1 through the inverted taper coupling waveguide 8, the power is equally divided into 128 paths after the optical beam splitting module 1, 128 sub-optical signals with equal power are obtained, and the 128 sub-optical signals are transmitted into the phase delay module 2, the herringbone waveguide array 21 respectively performs phase regulation on each sub-optical signal, so that any two adjacent sub-optical signals have the same phase difference, then the sub-optical signals are transmitted to the sinusoidal waveguide array 22 through the herringbone waveguide array 21, so that the waveguide spacing of each path is reduced to realize large-angle scanning, and finally the optical energy is radiated into space through the waveguide grating antenna module 3 to realize two-dimensional scanning.

[0043] The application divides input light into 128 beams of coherent light through the light splitting module 1, introduces a phase difference through each branch of the several-shaped waveguide array 21, realizes narrow spacing and low crosstalk between waveguides through the sinusoidal waveguide array 22, and finally radiates the light of the optical phased array into space through the waveguide grating antenna module 3. The optical phased array of the application does not need to use electrical or thermal adjustment to change the phase, and can realize large field-of-view scanning of the optical phased array after passing through the compactly arranged sinusoidal waveguide array 22.

[0044] Reference Figure 4 The inverted taper type coupling waveguide 8 includes a tapered region 81 and a stable region 82, and the end of the tapered region 81 away from the stable region 82 is an input end. The size of the tapered region 81 gradually increases from the input end to the end of the tapered region 81 close to the stable region 82 until the size is the same as that of the stable region 82.

[0045] In this embodiment, the inverted taper type coupler is designed based on input light of 1550nm. The waveguide size of the input end is 500nm wide, passes through a 4000nm tapered region 81, and then expands to the same size of 1000nm wide as the bus waveguide.

[0046] Specifically, the input light used in the application is a tunable narrow linewidth laser, and the tuning range is 1500-1600nm, and the linewidth is 80kHz.

[0047] Reference Figure 1 The structure of the silicon nitride layer 4 is shown in the figure. The silicon nitride layer 4 also includes a plurality of silicon nitride waveguides. The light splitting module 1, the phase delay module 2 and the waveguide grating antenna module 3 are connected to each other through the silicon nitride waveguides to realize low-loss optical interconnection between different modules.

[0048] The light splitting module 1 is composed of a plurality of cascaded multimode interference couplers. The input light is divided into 128 paths through the plurality of cascaded interference couplers.

[0049] Specifically, the cascaded multimode coupler divides the power of the optical signal into two parts. The input is a rectangular silicon nitride waveguide, the middle multimode interference coupling region is a rectangular silicon nitride waveguide with a larger size, and the output is two rectangular silicon nitride waveguides with the same size as the input. The length of the rectangular silicon nitride waveguide is 20-28μm.

[0050] In this embodiment, the light splitting module 1 includes one input waveguide, 28 two-way MMIs, seven groups of output waveguides, the first group has two output waveguides, the second group has four output waveguides, the third group has eight output waveguides, the fourth group has sixteen output waveguides, the fifth group has thirty-two output waveguides, the sixth group has sixty-four output waveguides, and the seventh group has one hundred and twenty-eight output waveguides.

[0051] Specifically, the light splitting module 1 is a cascade of several multimode interference couplers (MMI) that successfully average the input optical power in 128 branches. The MMIs use the principle of multimode interference to achieve efficient coupling and distribution of optical signals through precise geometric design and mode control. When the optical signal enters the interference coupler through the multimode waveguide, different modes in the waveguide will be coupled and interfered with each other. By designing a specific geometric shape and waveguide size, the light of a specific mode will interfere constructively or destructively at different times and spatial positions, thereby achieving the purpose of signal distribution or synthesis.

[0052] The zigzag waveguide array 21 includes 128 waveguides, of which N waveguides have different lengths. Specifically, 127 waveguides are zigzag waveguides, and the lowest one in the zigzag waveguide array 21 is a straight waveguide.

[0053] The sinusoidal waveguide array 22 includes 128 sinusoidal waveguides, of which any two adjacent sinusoidal waveguides have a spacing less than the wavelength length of the input light. Specifically, the sinusoidal waveguide refers to the design of the waveguide, in which the shape or path of the waveguide presents a sinusoidal curve.

[0054] Specifically, the input light passes through the zigzag waveguide array 21, and after calculation, the same phase difference is introduced to each branch, and then passes through the sinusoidal waveguide array 22. The sinusoidal waveguide array 22 arranges the waveguides compactly, and the waveguide spacing directly affects the scanning angle. Specifically, a waveguide array with a larger spacing will result in a smaller scanning angle, while a smaller waveguide spacing can achieve a larger scanning angle. Through the sinusoidal waveguide array 22, based on the waveguide refractive index distribution principle, the sinusoidal waveguide array 22 can reduce the waveguide spacing while achieving low crosstalk of the waveguide element and reducing the generation of sidelobes.

[0055] According to the calculated phase difference required for each branch, the length of the zigzag waveguide is designed to achieve the same phase difference between each adjacent waveguide. Specifically, after determining the phase difference of each adjacent branch, the length of each branch is designed according to the following formula.

[0056] The transverse scanning angle of the OPA satisfies the following formula:

[0057] sinθ=λΔφ / 2πd

[0058] Δφ=2πn eff ΔL / λ-2mπ

[0059] θ is the transverse scanning angle of the OPA, λ is the wavelength of the incident light in vacuum, Δφ is the phase difference between adjacent channels, d is the spacing of the zigzag waveguide, and n is the refractive index of the waveguide. effΔL is the effective refractive index of the zigzag waveguide at λ, ΔL is the path difference, and m is an integer. As ΔL increases sequentially, Δφ also changes, thereby altering the lateral scanning angle of the OPA. Thus, lateral scanning of the OPA is achieved under passive conditions.

[0060] According to the above formula, with λ constant, the ratio of Δφ / d determines the magnitude of θ. Therefore, after determining Δφ using a U-shaped waveguide, the magnitude of d becomes particularly important. However, reducing the waveguide spacing will cause inter-waveguide crosstalk. When light is injected into one of the waveguides, it excites the symmetric and antisymmetric supermodes supported by that structure. When the two waveguides are too close, the supermode constant will be non-zero, leading to periodic transmission of optical power between the waveguides, causing mode leakage and resulting in decreased light transmittance. Therefore, we use Δβ... bent The difference (propagation constant of the sinusoidal waveguide supermode) is set to zero to effectively suppress power exchange between waveguides. Δβ bent According to the following formula, we can obtain...

[0061] Δβ bent =ΔβJ04π 2 (W+G)n eff A / Pλ0

[0062] Where J0 is the zeroth-order Bessel function, Δβ is the difference in supermode constants, W is the width of the sinusoidal waveguide, G is the width of the gap between the two sinusoidal waveguides, A is the amplitude of the sinusoidal waveguide, and P is the period length of the sinusoidal waveguide. For the first zero of the Bessel function, we can obtain the optimal amplitude A that can bend Δβ to zero. opt .

[0063] A opt =2.405λP / 4π 2 (W+G)n eff

[0064] After determining parameters such as waveguide width, waveguide height, and waveguide spacing, the amplitude A of the sinusoidal waveguide can be obtained, resulting in very low inter-waveguide crosstalk. In this application, a silicon nitride sinusoidal waveguide with a width of 1000 nm, a waveguide spacing of 275 nm, a period of 10 μm, and a waveguide thickness of 500 nm is used, thus yielding an amplitude A of 1.056 μm.

[0065] refer to Figure 3 The waveguide grating antenna module 3 includes N waveguide gratings 7. Specifically, the waveguide gratings 7 are arranged according to the sinusoidal waveguide array 22, thus achieving a higher emissivity. The grating periods of the gratings are different, therefore, the scanning range and divergence angle are different. Among them, the grating duty cycle of the waveguide grating 7 is 0.5, and the grating period is 1μm.

[0066] The working principle of the present application is as follows: the external light source is directly coupled into the light splitting module 1 through the input end face of the inverted taper coupling waveguide 8, is split into 128 paths through cascading multiple MMIs, the 128 paths of light have the same power and the same phase, is made to have the same phase difference by the "J" shaped waveguide array, is then input into the sinusoidal waveguide array, so that the waveguide spacing of each path is reduced to realize large angle scanning, and finally the light energy is radiated into the space through the waveguide grating 7 to realize two-dimensional scanning.

[0067] Compared with the prior art, the passive large field of view silicon-based optical phased array of the present application has the following advantages:

[0068] (1) The optical phased array of the present application will not generate additional heat due to the operation of electronic elements during operation, thereby avoiding the influence of heat accumulation on system performance. The passive design does not require high driving electronics and power management system, which can significantly reduce the system cost, and is especially suitable for large-scale integrated applications. Combined with the silicon nitride material and the passive phased array technology, the overall system has more obvious advantages in optical performance, reliability, power consumption and cost.

[0069] (2) The present system is integrated on a silicon nitride chip, which is easy to mass-produce in actual production, has the advantages of small size, high flexibility, simple structure and easy compatibility with other systems.

[0070] (3) The sinusoidal waveguide structure shortens the waveguide spacing to below the wavelength length, which not only greatly improves the scanning angle, but also has a certain suppression on the sidelobe.

[0071] The above is only the preferred embodiment of the present application, and does not limit the patent range of the present application, and any equivalent structural transformation or direct / indirect application in other related technical fields under the utility model concept of the present application is included in the patent protection range of the present application.

Claims

1. A passive large field-of-view silicon-based optical phased array, comprising: The application relates to a silicon-based substrate, which comprises: a silicon dioxide buried oxide layer arranged on the upper surface of the silicon substrate; a silicon nitride layer arranged on the upper surface of the silicon dioxide buried oxide layer; the silicon nitride layer comprises an inverted taper type coupling waveguide, an optical beam splitting module, a phase delay module and a waveguide grating antenna module; the inverted taper type coupling waveguide is used for coupling input light into the optical beam splitting module; the optical beam splitting module is used for equally dividing optical signals generated by the input light into N sub-optical signals with equal power; the phase delay module comprises a herringbone type waveguide array and a sinusoidal type waveguide array; the herringbone type waveguide array is used for phase regulation of each sub-optical signal, so that any two adjacent sub-optical signals have the same phase difference; the sinusoidal type waveguide array is used for reducing the waveguide spacing; and the waveguide grating antenna module is used for radiating optical energy output by the sinusoidal type waveguide array, wherein N is greater than or equal to 2. The optical beam splitting module comprises a plurality of cascaded multimode interference couplers.

2. The passive large field-of-view liquid lens of claim 1, wherein, The cascaded multimode coupler divides the power of the optical signal into two parts, the input is a rectangular silicon nitride waveguide, the middle multimode interference coupling area is a rectangular silicon nitride waveguide with a larger size, and the output is two rectangular silicon nitride waveguides with the same size as the input, wherein the length of the rectangular silicon nitride waveguide is 20-28 mu m.

3. The passive large field-of-view liquid lens of claim 2, wherein, The herringbone type waveguide array comprises N waveguides, wherein the lengths of the N waveguides are different.

4. The passive large field-of-view liquid lens of claim 1, wherein, The sinusoidal type waveguide array comprises N sinusoidal type waveguides, wherein the spacing between any two adjacent sinusoidal type waveguides is less than the wavelength length of the input light.

5. The passive large field-of-view liquid lens of claim 1, wherein, The waveguide grating antenna module comprises N waveguide gratings.

6. The passive large field-of-view liquid lens of claim 1, wherein, The optical beam splitting module, the phase delay module and the waveguide grating antenna module are connected to each other through silicon nitride waveguides to realize low-loss optical interconnection between different modules.

7. The passive large field-of-view liquid lens of claim 1, wherein, The width of the silicon nitride waveguide ranges from 800 nm to 1000 nm.

8. The passive large field-of-view liquid crystal lens of claim 7, wherein, The height of the silicon substrate is greater than the height of the silicon dioxide buried oxide layer, and the height of the silicon dioxide buried oxide layer is greater than the height of the silicon nitride layer.

9. The passive large field-of-view liquid crystal optical phased array of claim 1, wherein, The inverted taper type coupling waveguide comprises a gradual change area and a stable area; the gradual change area is an input end away from one end of the stable area; and the size of the gradual change area gradually increases from the input end to the end of the gradual change area close to the stable area until the size of the gradual change area is the same as that of the stable area.

10. The passive large field-of-view liquid crystal optical phased array of claim 1, wherein, ​

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