Phase shifter with planar waveguide structure

Abstract

The invention discloses a planar waveguide structure phase shifter which comprises a substrate layer, a ground electrode layer, a lower isolation layer, a waveguide layer, an upper isolation layer and a signal electrode layer which are sequentially connected from bottom to top to form a multi-layer structure in the longitudinal direction. Wherein the waveguide layer is a wide waveguide made of an electro-optical material, and the signal electrode layer comprises a plurality of discrete metal electrodes. According to the working process of the phase shifter, when different voltages are applied to the signal electrode array, corresponding continuous refractive index gradient distribution is formed in the whole continuous waveguide according to the linear electro-optical effect of a waveguide material and an electric field generated by gradient potential distribution, and therefore specific phase distribution is generated. According to the phase shifter disclosed by the invention, gradient potential and refractive index distribution are generated on a single wide waveguide through the electrodes, continuous and linear modulation of the wavefront of a light beam is directly realized, and the inherent inter-channel crosstalk problem of a traditional discrete waveguide array is avoided.

Description

Technical Field

[0001] This invention belongs to the field of optical phase modulation technology and relates to a planar waveguide structure phase shifter. Background Technology

[0002] In the field of optoelectronics, the core device for wavefront shaping is the phase shifter. Traditional mainstream solutions are based on discrete waveguide channel arrays, with each channel integrating an independent phase shifter to control its phase. This architecture has inherent and fundamental drawbacks: firstly, it is complex to control, requiring independent and precise phase calibration and synchronous driving of multiple channels; secondly, due to the use of multiple physically separate yet closely arranged waveguide arrays, the inherent waveguide arrangement leads to severe optical crosstalk, causing mutual interference in the phase modulation of each channel.

[0003] It is precisely these defects at the device level that directly lead to their performance bottleneck in system applications. For example, in an optical phased array (OPA), in order to obtain a large beam scanning angle, the waveguide spacing must be reduced, but at the same time, crosstalk between channels will be drastically aggravated, which in turn will worsen the sidelobe level of the output beam, forming an irreconcilable contradiction between the scanning angle and the sidelobe suppression ratio.

[0004] To address the aforementioned issues, researchers have proposed several innovative solutions to overcome the limitations imposed by the beam scanning angle and sidelobe suppression ratio: The first approach involves inserting nanopairs of nanostructures, placing nanorods or nanoparticles in the gaps between adjacent waveguides. Specifically, this method works by leveraging the principle that nanorods or nanoparticle pairs can alter the local refractive index of the surrounding medium. When light propagates through the waveguide, the presence of the nanorods affects the propagation path and mode, thereby changing the coupling efficiency between waveguides, suppressing crosstalk, and improving the sidelobe suppression ratio.

[0005] The second method involves waveguide superlattices, which utilize five waveguides of different widths to form a superlattice period, with the superlattice itself arranged periodically along the array direction. Specifically, this method works by introducing a precisely defined periodic structural perturbation to disrupt the phase-matching condition required for energy exchange between adjacent waveguides. This achieves strong optical isolation between physically closely packed waveguides, thereby suppressing crosstalk and improving the sidelobe suppression ratio.

[0006] Existing solutions not only provide new ideas for the design and optimization of OPAs, but also open up new directions for the development of lidar technology. While these methods alleviate the conflict between field of view and sidelobe suppression ratio, they each introduce new problems: Inserting nanopair-like nanostructures presents significant fabrication challenges due to the small size of the inserted dielectric blocks (only tens of nanometers). Waveguide superlattices cannot be used for wavelength tuning, preventing two-dimensional scanning of the far-field beam from the OPA. This is because the different widths of the waveguides result in varying phase constants for the transmission modes. More importantly, the dispersion effects also differ with wavelength. Therefore, if the OPA is wavelength-tuned, waveguide antennas of different widths cannot achieve in-phase superposition in the far field.

[0007] In summary, existing technologies, whether traditional phase shifters based on discrete waveguide arrays or various improvements made to OPA systems, have failed to overcome the fundamental limitations of the discrete channel architecture itself, including control complexity, calibration difficulty, and optical crosstalk. Therefore, there is an urgent need for a phase shifter that innovates from the principle of phase modulation to achieve truly continuous phase control, thereby providing a core device foundation for high-performance beam deflection and scanning applications. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing discrete channel-based phase shifters, such as complex control, severe channel crosstalk, and difficulty in achieving continuous wavefront modulation. It provides a novel phase shifter with a simple structure, no need for inter-channel phase calibration, and the ability to achieve true continuous phase modulation, specifically a planar waveguide structure phase shifter.

[0009] To achieve the above objectives, the present invention employs the following technical solution: A planar waveguide phase shifter includes a substrate layer, a ground electrode layer, a lower isolation layer, a waveguide layer, an upper isolation layer, and a signal electrode layer connected sequentially from bottom to top; The upper surface of the upper isolation layer is a continuous, uninterrupted plane; The signal electrode layer includes a plurality of discrete metal electrodes, all of which are grid electrodes, and the plurality of grid electrodes form a 1 × 10⁻⁶ grid electrode along the width direction of the signal electrode layer. N Array structure.

[0010] A further improvement of the present invention is that: An xoy coordinate system is defined on the plane of the signal electrode layer, where the x-direction represents the length direction of the signal electrode layer and the y-direction represents the width direction of the signal electrode layer. The plurality of grid electrodes are of equal length along the x-direction of the signal electrode layer.

[0011] The 1 × N In the array structure, each grid electrode is distributed at equal intervals.

[0012] The 1 × N In the array structure, the width of each grid electrode is the same.

[0013] The thickness of the signal electrode layer is 0.1 to 0.4 μm.

[0014] The thickness of both the lower and upper isolation layers is greater than or equal to 1.5 μm.

[0015] The waveguide layer has a thickness of 300 nm to 900 nm.

[0016] A phase modulation method based on the planar waveguide structure phase shifter of the present invention includes the following steps: A voltage signal is input to several grid electrodes, the ground electrode layer is grounded, a continuous gradient potential is formed between the signal electrode layer and the ground electrode layer, a gradient electric field distribution along its width direction is generated in the waveguide layer, and a continuous refractive index gradient distribution is formed in the waveguide layer, which continuously modulates the phase of the passing light beam. The input of voltage signals to the plurality of grid electrodes includes: With 1 × N In the array structure, the first grid electrode is the starting electrode and the second grid electrode is the ending electrode. According to the arrangement order from the starting electrode to the ending electrode, starting from the starting electrode, a gradually increasing or gradually decreasing voltage signal is applied to each grid electrode in sequence. The first end and the second end are distributed relative to each other.

[0017] A phase modulation method based on the planar waveguide structure phase shifter of the present invention includes the following steps: A voltage signal is input to several grid electrodes, the ground electrode layer is grounded, a continuous gradient potential is formed between the signal electrode layer and the ground electrode layer, a gradient electric field distribution along its width direction is generated in the waveguide layer, and a continuous refractive index gradient distribution is formed in the waveguide layer, which continuously modulates the phase of the passing light beam. The input of voltage signals to the plurality of grid electrodes includes: With 1 × N In the array structure, the first grid electrode is the starting electrode and the second grid electrode is the ending electrode. According to the arrangement order from the starting electrode to the ending electrode, starting from the starting electrode, a voltage signal that first increases and then decreases is applied to each grid electrode in sequence. The first end and the second end are distributed relative to each other.

[0018] A phase modulation method for a planar waveguide phase shifter according to the present invention includes the following steps: A voltage signal is input to several grid electrodes, the ground electrode layer is grounded, a continuous gradient potential is formed between the signal electrode layer and the ground electrode layer, a gradient electric field distribution along its width direction is generated in the waveguide layer, and a continuous refractive index gradient distribution is formed in the waveguide layer, which continuously modulates the phase of the passing light beam. The input of voltage signals to the plurality of grid electrodes includes: With 1 × N In the array structure, the first grid electrode is the starting electrode and the second grid electrode is the ending electrode. According to the arrangement order from the starting electrode to the ending electrode, starting from the starting electrode, an equal voltage signal is applied to each grid electrode in sequence. The 1 × N In the array structure, starting from the starting electrode, the length of each grid electrode gradually increases; The first end and the second end are distributed relative to each other.

[0019] The phase shifter with continuous phase modulation function disclosed in this invention has the following advantages: (1) Channel crosstalk elimination: This invention abandons the traditional discrete waveguide array and uses a single, physically continuous wide waveguide as the light transmission medium. The light field propagates in the same medium, avoiding the inherent optical crosstalk caused by multiple independent waveguides being close to each other in the traditional architecture.

[0020] (2) Simplified control system: Phase modulation can be achieved by providing a voltage signal with a specific gradient (such as linear) distribution to a group of electrodes, eliminating the need for independent drive circuits and complex global phase calibration algorithms required for each channel in traditional arrays, which greatly reduces system complexity and power consumption.

[0021] (3) Excellent application performance: Due to its crosstalk-free continuous modulation capability, this phase shifter can simultaneously achieve large-angle scanning and high sidelobe suppression ratio when used to build systems such as optical phased arrays, breaking through the performance bottleneck of traditional OPA. In addition, this structure also has the advantages of being compact and easy to integrate.

[0022] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a planar waveguide phase shifter, comprising a substrate layer, a ground electrode layer, a lower isolation layer, a waveguide layer, an upper isolation layer, and a signal electrode layer connected sequentially from bottom to top, forming a multi-layer structure in the longitudinal direction. The waveguide layer is a wide waveguide made of electro-optic material, and the signal electrode layer includes several discrete metal electrodes. The phase shifter operates as follows: when different voltages are applied to the signal electrode array, based on the linear electro-optic effect of the waveguide material, the electric field generated by the gradient potential distribution will form a corresponding continuous refractive index gradient distribution throughout the continuous waveguide, thereby producing a specific phase distribution. The phase shifter disclosed in this invention directly achieves continuous and linear modulation of the beam wavefront by generating gradient potential and refractive index distribution on a single wide waveguide through electrodes. This phase shifter has a simple and compact structure and convenient control logic. Because it uses a single continuous waveguide structure, it physically avoids the inter-channel crosstalk problem inherent in traditional discrete waveguide arrays. When applied to systems such as optical phased arrays, it can effectively solve the trade-off between beam scanning range and sidelobe suppression ratio. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the phase shifter with continuous phase modulation capability disclosed in Embodiment 1 of the present invention, which generates a continuous potential distribution by a discrete electrode array. Figure 2 This is a schematic diagram of the phase shifter with continuous phase modulation capability disclosed in Embodiment 1 of the present invention, showing how end-face coupling and end-face coupling achieve beam deflection.

[0025] Figure 3 This is a cross-sectional schematic diagram of the thin-film lithium niobate continuous phase modulation phase shifter disclosed in Embodiment 1 of the present invention; Figure 4 This is the potential distribution diagram at the yoz section after a monotonically decreasing voltage signal is input into a discrete electrode array, as disclosed in Embodiment 1 of the present invention. Figure 5 This is a diagram showing the potential and refractive index distribution generated in the waveguide layer after a monotonically decreasing voltage signal is input into a discrete electrode array, as disclosed in Embodiment 1 of the present invention. Figure 6 This is a beam deflection diagram in the waveguide layer when a linear gradient voltage is input, as disclosed in Embodiment 1 of the present invention. Figure 7This is a schematic diagram of the phase shifter with continuous phase modulation capability disclosed in Embodiment 2 of the present invention, which generates a continuous potential distribution by a discrete electrode array. Figure 8 This is a schematic diagram of the beam expansion mechanism with continuous phase modulation capability disclosed in Embodiment 2 of the present invention, showing the operation of the beam expander achieved by end-face coupling-in and end-face coupling-out. Figure 9 This is a voltage distribution diagram generated in the waveguide layer after a voltage signal that first increases and then decreases is input into a discrete electrode array, as disclosed in Embodiment 2 of the present invention. Figure 10 This is a diagram illustrating the refractive index distribution in the waveguide layer after a voltage signal that first increases and then decreases is input into a discrete electrode array, as disclosed in Embodiment 2 of the present invention. Figure 11 This is a schematic diagram of the phase shifter with continuous phase modulation capability disclosed in Embodiment 3 of the present invention, which generates a continuous potential distribution by a discrete electrode array.

[0026] Figure 12 This is a beam deflection diagram in the waveguide layer when a linear gradient voltage is input, as disclosed in Embodiment 3 of the present invention. Figure 13 This is a structural diagram of a phase shifter with continuous phase modulation capability disclosed in Embodiment 3 of the present invention; Figure 14 This is a schematic diagram of the phase shifter with continuous phase modulation capability disclosed in Embodiment 4 of the present invention; Figure 15 This is a top view of the phase shifter with continuous phase modulation capability disclosed in Embodiment 4 of the present invention.

[0027] Wherein: 1-substrate layer; 2-ground electrode layer; 3-isolation layer; 301-upper isolation layer; 302-lower isolation layer; 4-waveguide layer; 5-signal electrode layer. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0032] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0033] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0034] The present invention will now be described in further detail with reference to the accompanying drawings: See Figures 1 to 15 This invention discloses a planar waveguide phase shifter, the core of which is to generate an electric field on a single continuous waveguide through a discrete electrode array, thereby achieving continuous and linear modulation of the beam phase.

[0035] First, the technical terms used in this embodiment will be explained: Optical phased array: a type of optoelectronic chip that can achieve beam scanning by voltage control. It is generally composed of waveguide arrays whose phase can be adjusted independently. After beam combining at the output end, the waveguide array achieves different deflection angles through different phase distributions. The phase adjustment is achieved by the independent control of electrodes near the waveguide.

[0036] Sidelobe noise: The output beam of an optical phased array is usually not a single perfect spot, but rather has many weaker secondary spots on both sides of the main spot, which is called sidelobe noise. Sidelobe noise is a secondary spot in the beam radiation mode and is generally undesirable because it may cause signal leakage, interfere with other communication channels, or be interfered with by nearby signals.

[0037] Linear electro-optic effect: The refractive index of lithium niobate material changes linearly with the change of the applied electric field.

[0038] Thin-film lithium niobate: a thin-film material with significant electro-optic effect, whose refractive index can be changed by applying an external electric field.

[0039] Z-cut lithium niobate films: Lithium niobate films are available in three tangential directions: x, y, and z. To achieve maximum modulation efficiency, the applied electric field direction generally needs to be parallel to the tangential direction of the lithium niobate film. Therefore, z-cut lithium niobate films are typically chosen for the vertical electric field.

[0040] Crosstalk: When adjacent waveguide channels are physically close together, the optical field transmitted in one waveguide will leak into the adjacent waveguide, introducing uncontrollable additional phase errors. This phenomenon is most common at the output beam-combining point.

[0041] See Figure 1 This invention discloses a planar waveguide phase shifter, utilizing an electro-optic material as the optical waveguide layer to construct a multi-layer structure in the vertical direction. The structure includes, from bottom to top, a substrate layer 1, a ground electrode layer 2, a lower isolation layer 302, a waveguide layer 4, an upper isolation layer 301, and a signal electrode layer 5. The signal electrode layer 5 comprises several discrete metal electrodes, all of which are grid electrodes. These grid electrodes form a 1 × 10⁻⁶ pattern along the width direction of the signal electrode layer 5. N The array structure has an upper isolation layer 301 that is a continuous, uninterrupted plane.

[0042] Furthermore, in this embodiment of the invention, an xoy coordinate system is defined on the plane containing the signal electrode layer 5, where the x-direction is the length direction of the signal electrode layer 5 and the y-direction is the width direction of the signal electrode layer 5. The length direction of each gate electrode is parallel to the length direction of the signal electrode layer 5, and the gate electrodes are uniformly or non-uniformly distributed along the y-direction to form a 1 × 10⁻⁶ grid. N An array, with electrodes distributed at equal or non-equal lengths along the x-direction; each electrode is named along the +y-direction. ( ).

[0043] During operation, ground electrode layer 2 is grounded, and then a voltage signal is applied to each discrete metal electrode, named respectively. voltage signal The change occurs in a monotonically increasing or decreasing manner along the +y direction, either linearly or non-linearly, specifically by 1 × N In the array structure, the first grid electrode is the starting electrode and the second grid electrode is the ending electrode. According to the arrangement order from the starting electrode to the ending electrode, a specific voltage signal is applied to each grid electrode in sequence, starting from the starting electrode. The first and second ends are relatively distributed.

[0044] Furthermore, in this embodiment of the invention, the voltage signal input to the signal electrode layer 5 includes one or more of DC, low-frequency, and high-frequency voltage signals.

[0045] Furthermore, in this embodiment of the invention, the thickness of the signal electrode layer 5 and the ground electrode layer 2 is 0.1 to 0.4 μm.

[0046] Furthermore, in this embodiment of the invention, the refractive indices of the lower isolation layer 302 and the upper isolation layer 301 are less than the refractive index of the waveguide layer 4, which serves to confine the light beam and prevent the light beam from radiating to the outer layer.

[0047] Furthermore, in this embodiment of the invention, the structure of the waveguide layer 4 can be a ridge waveguide, a planar waveguide, or a rectangular waveguide; the material of the waveguide layer 4 is an electro-optic material, which can be lithium niobate, lithium tantalate, or gallium arsenide, but is not limited to the above materials.

[0048] Furthermore, in this embodiment of the invention, the thickness of the waveguide layer 4 is 300 nanometers to 900 nanometers.

[0049] It should be noted that in this embodiment, the optical coupling input and output methods of the device can be grating coupling or end face coupling, and are not limited to any combination of the two.

[0050] Furthermore, in this embodiment of the invention, the substrate layer 1 is made of one or more of silicon, glass, lithium niobate, sapphire, and quartz, serving a supporting function.

[0051] Furthermore, in this embodiment of the invention, the thickness of the lower isolation layer 302 and the upper isolation layer 301 is not less than 1.5 micrometers, so as to reduce the plasma absorption of the metal electrode.

[0052] Furthermore, in this embodiment of the invention, each electrode unit in the signal electrode layer 5 is a completely identical grid electrode unit, and the distribution pattern is an equal-spaced and equal-width distribution.

[0053] The core of the working principle of this invention lies in: An electric field is generated by a discrete electrode array positioned above a single continuous wide waveguide, thereby inducing the desired refractive index gradient in this continuous medium. Since light always propagates within the same waveguide, there are no boundaries between multiple waveguides, thus physically avoiding the inter-channel crosstalk problem that is insurmountable in traditional waveguide arrays. Based on this crosstalk-free single optical channel, continuous and precise modulation of the beam wavefront can be achieved by adjusting the voltage distribution.

[0054] The phase modulation method for the planar waveguide phase shifter disclosed in this embodiment includes the following steps: A voltage signal is input into the grid-shaped electrode array of the signal electrode layer 5, and the ground electrode layer 2 is grounded. A potential with a stepped or gradient distribution is generated in the region between the signal electrode layer 5 and the ground electrode layer 2, and phase modulation is achieved through the electro-optic effect of the waveguide layer.

[0055] Furthermore, inputting voltage signals to several grid electrodes includes: With 1 × N In the array structure, the first grid electrode is the starting electrode and the second grid electrode is the ending electrode. According to the arrangement order from the starting electrode to the ending electrode, starting from the starting electrode, a gradually increasing or gradually decreasing voltage signal is applied to each grid electrode in sequence. The first and second ends are relatively distributed.

[0056] By adjusting the amplitude of the input voltage, a linear or nonlinear electric field distribution is generated in the waveguide layer 4. Based on the electro-optic properties of the electro-optic material, a continuous refractive index gradient distribution is formed in the waveguide layer 4, thereby generating a customized phase distribution for the incident light. Figure 1 The schematic diagram illustrates how the voltage, following a linear, monotonically decreasing distribution, generates a corresponding refractive index gradient in the waveguide layer, thereby producing a corresponding phase wavefront for the incident light. Ultimately, the beam exits from the end of the device and performs different functions according to the set voltage.

[0057] This invention utilizes electro-optic materials as optical waveguide layers to construct a multi-layer structure in the vertical direction, comprising, from bottom to top, a substrate layer 1, a ground electrode layer 2, a lower isolation layer 302, a waveguide layer 4, an upper isolation layer 301, and a signal electrode layer 5. The signal electrode layer 5 is... N An array of discrete grid-shaped electrode units, when different voltages are applied to the electrode array, will generate a corresponding continuous refractive index gradient distribution throughout the continuous waveguide due to the linear electro-optic effect of the waveguide material. This results in a specific phase distribution. When linear voltages are applied sequentially to the array electrodes, a linear gradient voltage distribution and a local linear refractive index gradient change will be generated in the waveguide layer, thus providing a specific phase wavefront to the passing light beam.

[0058] The structure of the present invention will be described in detail below with reference to the following embodiments: Example 1 See Figures 1 to 6 This embodiment discloses a specific phase shifter based on continuous phase modulation of thin-film lithium niobate, specifically including: like Figure 2 As shown, the phase shifter in this embodiment includes, from bottom to top, a substrate layer 1, a ground electrode layer 2, a lower isolation layer 302, a waveguide layer 4, an upper isolation layer 301, and a signal electrode layer 5.

[0059] In this embodiment, the isolation layer 3 includes an upper isolation layer 301 and a lower isolation layer 302, and the waveguide layer 4 is located between the lower isolation layer 302 and the upper isolation layer 301. The upper surface of the upper isolation layer 301 is a continuous and uninterrupted plane.

[0060] In this embodiment, the substrate layer 1 is made of lithium niobate, which provides good support.

[0061] In this embodiment, both the upper isolation layer 301 and the lower isolation layer 302 are made of silicon dioxide, which can provide a large refractive index difference, which is beneficial to increasing the confinement effect on the light beam. The thickness of the upper isolation layer 301 is 1.7 micrometers, and the thickness of the lower isolation layer 302 is 2 micrometers.

[0062] In this embodiment, the waveguide layer 4 is made of Z-cut thin-film lithium niobate, and has a ridge waveguide structure with a ridge thickness of 120 nanometers and a flat plate thickness of 180 nanometers.

[0063] In this embodiment, the thickness of the ground electrode layer 2 is 200 nanometers, the thickness of the signal electrode layer 5 is 300 nanometers, and the material of both the ground electrode layer 2 and the signal electrode layer 5 is gold.

[0064] like Figure 3 As shown, in this embodiment, the number of traveling wave electrodes is four. The first traveling wave electrode, the second traveling wave electrode, the third traveling wave electrode, and the fourth traveling wave electrode are named sequentially from y to +y. Each electrode unit is an identical grid electrode unit, distributed with equal spacing and width. Each electrode is 2 micrometers wide and the gap is 2 micrometers. The equally spaced and equally wide electrode layout is conducive to generating a more uniform and linear gradient electric field distribution in the waveguide.

[0065] In this embodiment, the substrate layer 1, ground electrode layer 2, upper isolation layer 301, lower isolation layer 302, waveguide layer 4, and signal electrode layer 5 are all left-right symmetrical structures, which makes the device structure design simpler and more practical.

[0066] In this embodiment, when the input voltages are respectively hour, Figure 4The potential distribution of the beam deflector in the yoz section is shown.

[0067] like Figure 5 As shown, when no voltage is applied to the four traveling wave electrodes, The potential and refractive index of waveguide layer 4 both change to zero, and their distributions are both linear. When a gradient voltage is applied to the four traveling wave electrodes, a quasi-linear and monotonically decreasing potential curve is generated in waveguide layer 4. Based on the electro-optic effect of lithium niobate crystal, a corresponding quasi-linear refractive index gradient distribution is generated in waveguide layer 4.

[0068] In this embodiment, the polarization direction of the incident linearly polarized light is along the z-axis, and the light propagates along the x-axis. The beam can achieve maximum modulation coefficient in the lithium niobate waveguide. Phase modulation. The beam deflector, under a linear gradient input voltage, in the waveguide layer... The refractive index gradient distribution formed from y to +y. Since the light beam always propagates in the direction of higher refractive index, the light beam can propagate in the lithium niobate waveguide towards... Deflection along the y-axis, such as Figure 6 As shown, to better illustrate beam deflection within the waveguide, [the following is an example of the method used]. Figure 6 The x-axis has been compressed.

[0069] Example 2 See Figures 7 to 10 This invention discloses a specific phase shifter based on continuous phase modulation of thin-film lithium niobate, specifically comprising: like Figure 7 As shown, the phase shifter in this embodiment includes, from bottom to top, a substrate layer 1, a ground electrode layer 2, a lower isolation layer 302, a waveguide layer 4, an upper isolation layer 301, and a signal electrode layer 5.

[0070] In this embodiment, the isolation layer 3 includes an upper isolation layer 301 and a lower isolation layer 302, and the waveguide layer 4 is located between the lower isolation layer 302 and the upper isolation layer 301.

[0071] In this embodiment, the substrate layer 1 is made of silicon and has a thickness of 525 micrometers, providing good support.

[0072] In this embodiment, both the upper isolation layer 301 and the lower isolation layer 302 are made of silicon dioxide, which can provide a large refractive index difference, which is beneficial to increase the confinement effect on the light beam. The thickness of the upper isolation layer 301 is 1.7 micrometers, the thickness of the lower isolation layer 302 is 2 micrometers, and the upper end surface of the upper isolation layer 301 is a continuous and uninterrupted plane.

[0073] In this embodiment, the waveguide layer 4 is a heterogeneous integrated waveguide of Z-cut thin-film lithium niobate and silicon nitride, with a ridge waveguide structure. The lithium niobate waveguide has a thickness of 300 nanometers, and the silicon nitride waveguide layer has a thickness of 300 nanometers.

[0074] In this embodiment, the thickness of the ground electrode layer 2 is 200 nanometers, the thickness of the signal electrode layer 5 is 300 nanometers, and the material of both the ground electrode layer 2 and the signal electrode layer 5 is gold.

[0075] like Figure 8 As shown, in this embodiment, the number of traveling wave electrodes is 8. The electrodes from y to +y are named sequentially as the first traveling wave electrode, the second traveling wave electrode, the third traveling wave electrode, the fourth traveling wave electrode, the fifth traveling wave electrode, the sixth traveling wave electrode, the seventh traveling wave electrode, and the eighth traveling wave electrode. Each electrode unit is an identical grid electrode unit, distributed with equal spacing and width. Each electrode is 2 micrometers wide, and the gap is 1.5 micrometers. The equally spaced and equally wide electrode layout is beneficial for generating a more uniform and linear gradient electric field distribution in the waveguide.

[0076] In this embodiment, the substrate layer 1, ground electrode layer 2, upper isolation layer 301, lower isolation layer 302, and waveguide layer signal electrode layer 5 are all left-right symmetrical structures, which makes the device structure design simpler and more practical.

[0077] In this embodiment, when the input voltages are respectively hour, Figure 9 The voltage distribution diagram of the beam diffuser is shown. Figure 10 The refractive index distribution curve of the beam diffuser in the yoz section is shown.

[0078] When no voltage is applied to the four traveling wave electrodes The potential and refractive index of waveguide layer 4 both change to zero, exhibiting no phase adjustment capability. When a gradient voltage that first increases and then decreases is applied to the eight traveling wave electrodes, a potential curve that first increases and then decreases is generated in waveguide layer 4. Based on the electro-optic effect of lithium niobate crystal, a corresponding refractive index distribution that first increases and then decreases is generated in waveguide layer 4.

[0079] It should be noted that in this embodiment, when a gradient voltage that first increases and then decreases is applied to the traveling wave electrode, the voltage values ​​on the left and right are symmetrical with the largest peak voltage as the reference point.

[0080] In this embodiment, the polarization direction of the incident linearly polarized light is along the z-axis, and the light propagates along the x-axis. The beam can achieve maximum modulation coefficient in the lithium niobate waveguide. Phase modulation. The beam diffuser, under a specific gradient input voltage, modulates the phase in the waveguide layer. A specific refractive index distribution is formed from the y to the +y direction. Since the light beam always propagates in the direction of higher refractive index, the beam's emission aperture in the waveguide decreases, and the beam spread angle increases.

[0081] Example 3 See Figures 11 to 13 This embodiment discloses a specific phase shifter based on continuous phase modulation of thin-film lithium niobate, specifically including: like Figure 11 As shown, the phase shifter in this embodiment includes, from bottom to top, a substrate layer 1, a ground electrode layer 2, a lower isolation layer 302, a waveguide layer 4, an upper isolation layer 301, and a signal electrode layer 5.

[0082] In this embodiment, the isolation layer 3 includes an upper isolation layer 301 and a lower isolation layer 302, and the waveguide layer 4 is located between the lower isolation layer 302 and the upper isolation layer 301. The upper surface of the upper isolation layer 301 is a continuous and uninterrupted plane.

[0083] In this embodiment, the substrate layer 1 is made of lithium niobate with a thickness of 525 micrometers, providing good support.

[0084] In this embodiment, both the upper isolation layer 301 and the lower isolation layer 302 are made of silicon dioxide, which can provide a large refractive index difference, which is beneficial to increasing the confinement effect on the light beam. The thickness of the upper isolation layer 301 is 1.7 micrometers, and the thickness of the lower isolation layer 302 is 2 micrometers.

[0085] In this embodiment, the waveguide layer 4 is made of Z-cut thin-film lithium niobate and has a planar waveguide structure with a thickness of 300 nanometers.

[0086] In this embodiment, the thickness of the ground electrode layer 2 is 200 nanometers, the thickness of the signal electrode layer 5 is 300 nanometers, and the material of both the ground electrode layer 2 and the signal electrode layer 5 is gold.

[0087] This embodiment uses eight traveling wave electrodes, along... The electrodes are arranged sequentially from y to +y, representing the first to eighth traveling wave electrodes, respectively. (See also...) Figure 13 Each electrode is composed of grid-like units, with their width increasing linearly in the range of 1–4 micrometers, and the gap increasing synchronously in the range of 1–3 micrometers. This electrode layout, with both width and gap increasing gradually, helps to form a more significant refractive index gradient distribution in the waveguide.

[0088] In this embodiment, the substrate layer 1, the ground electrode layer 2, the upper isolation layer 301, the lower isolation layer 302, and the waveguide layer 4 are all left-right symmetrical structures, which makes the device structure design simpler and more practical.

[0089] When no voltage is applied to the eight traveling wave electrodes In waveguide layer 4, both the potential and refractive index changes are zero, resulting in no phase modulation and linear propagation of the light field along the waveguide. When an increasing gradient voltage is applied to the eight traveling wave electrodes, a quasi-linear and monotonically increasing potential curve is generated in waveguide layer 4. Based on the electro-optic effect of lithium niobate crystals, a corresponding quasi-linear refractive index gradient distribution is generated in waveguide layer 4.

[0090] In this embodiment, the polarization direction of the incident linearly polarized light is along the z-axis, and the light propagates along the x-axis. The beam can achieve maximum modulation coefficient in the lithium niobate waveguide. Phase modulation. The beam deflector, under a linear gradient input voltage, in the waveguide layer... The refractive index gradient distribution formed from the y-axis to the +y-axis. Since the light beam always propagates in the direction of higher refractive index, it can be deflected towards the +y-axis in the lithium niobate waveguide, such as... Figure 12 As shown, to better illustrate beam deflection within the waveguide, [the following is an example of the method used]. Figure 12 The x-axis has been compressed.

[0091] Example 4 See Figures 14 to 15 This embodiment discloses a specific phase shifter based on continuous phase modulation of thin-film lithium niobate, specifically including: like Figure 14 As shown, the phase shifter in this embodiment includes, from bottom to top, a substrate layer 1, a ground electrode layer 2, a lower isolation layer 302, a waveguide layer 4, an upper isolation layer 301, and a signal electrode layer 5.

[0092] In this embodiment, the isolation layer 3 includes an upper isolation layer 301 and a lower isolation layer 302, and the waveguide layer 4 is located between the lower isolation layer 302 and the upper isolation layer 301. The upper surface of the upper isolation layer 301 is a continuous and uninterrupted plane.

[0093] In this embodiment, the substrate layer 1 is made of silicon and has a thickness of 525 micrometers, providing good support.

[0094] In this embodiment, both the upper isolation layer 301 and the lower isolation layer 302 are made of silicon dioxide, which can provide a large refractive index difference, which is beneficial to increasing the confinement effect on the light beam. The thickness of the upper isolation layer 301 is 1.7 micrometers, and the thickness of the lower isolation layer 302 is 2 micrometers.

[0095] In this embodiment, the waveguide layer 4 is made of Z-cut thin-film lithium niobate and has a planar waveguide structure with a thickness of 300 nanometers.

[0096] In this embodiment, the thickness of the ground electrode layer 2 is 200 nanometers, the thickness of the signal electrode layer 5 is 300 nanometers, and the material of both the ground electrode layer 2 and the signal electrode layer 5 is gold.

[0097] like Figure 15 As shown, in this embodiment, the number of traveling wave electrodes is four, along... The first to fourth traveling wave electrodes are located sequentially from y to +y. Each electrode employs a grid structure, with its length along... The length increases progressively from y to +y, but the width and spacing remain constant at 2 micrometers. This design, with equal width and spacing combined with increasing length, can create a specific electric field distribution in the waveguide.

[0098] In this embodiment, the substrate layer 1, the ground electrode layer 2, the upper isolation layer 301, the lower isolation layer 302, and the waveguide layer 4 are all left-right symmetrical structures, which makes the device structure design simpler and more practical.

[0099] When no voltage is applied to the four traveling wave electrodes The changes in potential and refractive index of waveguide layer 4 are both 0, there is no phase modulation, and the light field propagates in a straight line along the waveguide.

[0100] When equal voltages are applied to the four traveling wave electrodes, a non-uniform electric field distribution is formed along the z-direction in waveguide layer 4. Based on the electro-optic effect of lithium niobate, the refractive index of the waveguide changes accordingly.

[0101] In this embodiment, the incident light is linearly polarized light polarized along the z-direction and propagates in the x-direction, thus achieving the maximum electro-optic modulation coefficient. This enables efficient phase modulation. Under a non-uniform refractive index distribution, the optical field phase is modulated, generating a tilted phase wavefront. Therefore, under the excitation of the electrode structure, the beam deflects along the +y direction in the waveguide, thereby achieving continuous phase modulation and beam control.

[0102] This invention uses continuous-channel optical waveguides to replace the discrete waveguide arrays in traditional optical phased arrays for beam deflection. The continuous phase model proposed in this invention fundamentally solves the trade-off between field of view and beam quality, while achieving large angles and high sidelobe suppression ratios. Traditional optical phased arrays based on discrete waveguide arrays easily introduce additional phase errors in the waveguide channels, making beam control require complex phase calibration algorithms and control circuits, and the voltage of each waveguide needs to be independently adjusted. This invention avoids phase errors through continuous-channel optical waveguides, eliminating the need for phase calibration and requiring only a set of control voltages with linear gradients.

[0103] In summary, the phase shifter provided by this invention achieves continuous and linear modulation of the beam wavefront through the aforementioned structure and operating method. Benefiting from its crosstalk-free continuous modulation characteristics, this phase shifter can effectively resolve the contradiction between scanning range and sidelobe suppression ratio when constructing systems such as optical phased arrays.

[0104] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A planar waveguide phase shifter, characterized in that, It includes a substrate layer (1), a ground electrode layer (2), a lower isolation layer (302), a waveguide layer (4), an upper isolation layer (301), and a signal electrode layer (5) connected sequentially from bottom to top; The upper surface of the upper isolation layer (301) is a continuous and uninterrupted plane; The signal electrode layer (5) includes a plurality of discrete metal electrodes, all of which are grid electrodes, and the plurality of grid electrodes form a 1 × 10⁻⁶ grid electrode along the width direction of the signal electrode layer (5). N Array structure.

2. A planar waveguide phase shifter according to claim 1, characterized in that, The thickness of the signal electrode layer (5) is 0.1 to 0.4 μm.

3. A planar waveguide phase shifter according to claim 1, characterized in that, The thickness of both the lower isolation layer (302) and the upper isolation layer (301) is greater than or equal to 1.5 μm.

4. A planar waveguide phase shifter according to claim 1, characterized in that, The waveguide layer (4) has a thickness of 300 nm to 900 nm.

5. A phase modulation method based on the planar waveguide structure phase shifter of claim 1, characterized in that, Includes the following steps: A voltage signal is input to several grid electrodes, the ground electrode layer (2) is grounded, a continuous gradient distribution potential is formed between the signal electrode layer (5) and the ground electrode layer (2), a gradient electric field distribution along its width direction is generated in the waveguide layer (4), and a continuous refractive index gradient distribution is formed in the waveguide layer (4), and the passing beam is continuously phase modulated. The input of voltage signals to the plurality of grid electrodes includes: With 1 × N In the array structure, the first grid electrode is the starting electrode and the second grid electrode is the ending electrode. According to the arrangement order from the starting electrode to the ending electrode, starting from the starting electrode, a gradually increasing or gradually decreasing voltage signal is applied to each grid electrode in sequence. The first end and the second end are distributed relative to each other.

6. A phase modulation method based on the planar waveguide structure phase shifter of claim 1, characterized in that, Includes the following steps: A voltage signal is input to several grid electrodes, the ground electrode layer (2) is grounded, a continuous gradient distribution potential is formed between the signal electrode layer (5) and the ground electrode layer (2), a gradient electric field distribution along its width direction is generated in the waveguide layer (4), and a continuous refractive index gradient distribution is formed in the waveguide layer (4), and the passing beam is continuously phase modulated. The input of voltage signals to the plurality of grid electrodes includes: With 1 × N In the array structure, the first grid electrode is the starting electrode and the second grid electrode is the ending electrode. According to the arrangement order from the starting electrode to the ending electrode, starting from the starting electrode, a voltage signal that first increases and then decreases is applied to each grid electrode in sequence. The first end and the second end are distributed relative to each other.

7. A phase modulation method based on the planar waveguide structure phase shifter of claim 1, characterized in that, Includes the following steps: A voltage signal is input to several grid electrodes, the ground electrode layer (2) is grounded, a continuous gradient distribution potential is formed between the signal electrode layer (5) and the ground electrode layer (2), a gradient electric field distribution along its width direction is generated in the waveguide layer (4), and a continuous refractive index gradient distribution is formed in the waveguide layer (4), and the passing beam is continuously phase modulated. The input of voltage signals to the plurality of grid electrodes includes: With 1 × N In the array structure, the first grid electrode is the starting electrode and the second grid electrode is the ending electrode. According to the arrangement order from the starting electrode to the ending electrode, starting from the starting electrode, an equal voltage signal is applied to each grid electrode in sequence. The 1 × N In the array structure, starting from the starting electrode, the length of each grid electrode gradually increases; The first end and the second end are distributed relative to each other.

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