An integrated optical switch type optical scanning device

Abstract

The application provides an integrated optical switch type optical scanning device, and belongs to the technical field of optical scanning. The integrated optical switch type optical scanning device comprises an input waveguide, a multimode waveguide and a plurality of arbitrarily bendable output waveguides which are connected in sequence, and further comprises a plurality of strip electrodes located above the multimode waveguide, the plurality of strip electrodes can modulate the propagation path of the light field in the multimode waveguide, can selectively guide the light into the output waveguides with different bending angles, and realize optical scanning; the light field at the output end of the output waveguide at the chip waveguide end surface satisfies the Snell law. Since the output waveguide end surface of the device does not need to be specially treated to emit light, and can realize large-angle scanning through end surface refraction, the optical switch type optical scanning device can effectively reduce the design difficulty and process cost, and realize large-angle and high-precision optical scanning on a chip.

Description

Technical Field

[0001] This invention relates to the field of optical scanning, and in particular to an integrated optical switch type optical scanning device. Background Technology

[0002] LiDAR (Light Detection and Ranging) has functions such as ranging, positioning, and mapping of terrain features. As an important sensor, it is widely used in fields such as autonomous driving, drones, and intelligent robots. Its performance parameters directly determine the detection accuracy, distance, and response time.

[0003] The common scanning principles of lidar in related technologies generally include: mechanical rotation type; semi-solid-state type, such as microelectromechanical systems (MEMS) type; and solid-state type, such as FLASH type, optical phased array (OPA) type, and optical switch array type. Among these, mechanical and semi-solid-state lidars, due to the need for high-frequency and complex mechanical rotation, have poor vibration resistance and short lifespan. FLASH type lidar typically uses VCSEL laser arrays as the emission source, and its detection range and field of view are limited by the power and number of VCSEL lasers. Optical phased array and optical switch array types are mainly based on photonic integrated circuits (PIC), which can effectively reduce device size, achieve high integration, and low power consumption. The transmitting end of an optical phased array lidar mainly consists of an optical beam splitter, an optical phase shifter, and an optical output antenna array. By changing the phase on each beam-splitting waveguide individually through thermo-optical or electro-optical methods, the scanning angle of the output light field is adjusted, thereby achieving the optical scanning function. Understandably, its adjustable precision and angle are limited by the number of optical phase shifters and the optical output antenna array. The relationship between the phase change and the refractive index change on the optical phase shifter is as follows: Where Δn represents the refractive index change, L is the length of the beam splitter waveguide, and λ is the operating wavelength. It is understandable that optical phase changes are sensitive to factors such as device fabrication errors and ambient temperature, and the complexity of fabrication and R&D costs increase with the number of output antenna arrays. Unlike optical phased array solutions, optically switched lidar does not require simultaneous phase adjustment of multiple optical phase shifters; it only needs to switch the light to a specific output waveguide antenna to achieve scanning at different angles. To achieve large-area, high-precision scanning, an optical switch array composed of numerous optical switch ports is required. Existing integrated optical switches are mainly based on phase-adjustable Mach-Zehnder Interferometer (MZI) and MicroRing Resonator (MRR) components, with a single component only achieving 1×2 or 2×2 optical switching functionality. Its main control principle is the same as that of optical phased array lidar, achieving optical switching functionality by adjusting the phase. To realize a large-port optical switch array, a complex cascade design is required. This will lead to problems such as high loss, complex processes, difficult packaging, and high R&D costs. Summary of the Invention

[0004] The purpose of this invention is to overcome the aforementioned shortcomings and provide an integrated optical switch-type optical scanning device. Because this device is fabricated from an optical waveguide material with thermo-optical effects and employs multiple arbitrarily bendable output waveguides, light can be emitted directly from the output waveguide end faces without special treatment, and large-angle scanning can be achieved through end-face refraction. The optical switch-type optical scanner of this invention can effectively reduce design complexity and achieve on-chip large-angle, high-precision optical scanning.

[0005] In a first aspect, an integrated optical switch type optical scanning device is provided. This optical scanning device includes:

[0006] One input waveguide, one multimode waveguide, multiple arbitrarily bendable output waveguides, and multiple strip electrodes;

[0007] The input waveguide, the multimode waveguide, and the plurality of arbitrarily bendable output waveguides are arranged along a first direction, and the input waveguide is connected to the input end of the multimode waveguide, and the plurality of arbitrarily bendable output waveguides are connected to the output end of the multimode waveguide.

[0008] Multiple strip electrodes are positioned opposite the multimode waveguide and spaced apart along a second direction perpendicular to the first direction; the multiple strip electrodes are used to modulate the propagation path of the light field in the multimode waveguide, thereby selectively guiding light into output waveguides with different bending angles;

[0009] The input waveguide, multimode waveguide, and multiple arbitrarily bendable output waveguides are made of optical waveguide materials with thermo-optic effects;

[0010] Let θ1 be the angle between the optical field of the output waveguide and the normal to the waveguide end face of the optical scanning device, and θ2 be the angle between the optical field emitted from the end face and the normal to the waveguide end face of the optical scanning device. Then θ1 and θ2 satisfy:

[0011] n1sinθ1=n2sinθ2

[0012] Where n1 is the effective refractive index of the mode at the output end of the output waveguide, and n2 is the refractive index of the output scan free space.

[0013] The integrated optical switch-type optical scanning device provided in this application adopts a planar waveguide structure. These multiple output waveguides can be bent according to design requirements, and the optical field propagation path in the multimode waveguide can be modulated by multiple strip electrodes to guide light into different output waveguides, thereby achieving optical scanning. This optical switch-type optical scanner can effectively reduce design complexity and manufacturing costs, achieving on-chip large-angle, high-precision optical scanning.

[0014] Preferably, the arbitrarily bendable output waveguide includes an output wedge waveguide and several straight waveguides and curved waveguides connected in series. The wider end of the output wedge waveguide is connected to the output end of the multimode waveguide, and the narrower end of the output wedge waveguide is connected to the straight or curved waveguide to reduce coupling loss. The several straight and curved waveguides connected in series are designed as needed to achieve the required scanning angle and position.

[0015] Preferably, the last section of the output waveguide that can be bent arbitrarily is close to the waveguide end face of the optical scanning device is designed as a multimode waveguide or a tapered waveguide structure to control the size of the near-field output spot, thereby reducing the far-field divergence angle and realizing the directional emission of an approximate plane wave within a certain distance range.

[0016] Preferably, the input waveguide includes an input wedge waveguide, the wider end of which is connected to the input end of the multimode waveguide to reduce coupling loss. The other end of the waveguide is narrower to facilitate connection to a single-mode waveguide or optical fiber.

[0017] Optionally, the input waveguide further includes an input straight waveguide, which is a single-mode waveguide, and the input straight waveguide is connected to the end of the input wedge waveguide away from the multimode waveguide.

[0018] Optionally, the integrated optical switch type optical scanning device includes: a first core layer, a first cladding layer, and a second cladding layer. An input waveguide, a multimode waveguide, and multiple arbitrarily bendable output waveguides are all located in the first core layer. The first core layer is situated between the first cladding layer and the second cladding layer, and multiple strip electrodes are located on the side of the first cladding layer away from the first core layer, and are positioned directly opposite the multimode waveguide. The refractive index of the first core layer is greater than that of the first cladding layer and is also greater than that of the second cladding layer. The refractive indices of the first cladding layer and the second cladding layer can be the same or different. The material of the first core layer can be a polymer with a refractive index n = 1.47, and both the first and second cladding layers can be polymers with a refractive index n = 1.45.

[0019] Optionally, the integrated optical switch type optical scanning device further includes a dispersive element disposed in a third direction to realize angular scanning in the third direction; the third direction is simultaneously perpendicular to the first direction and the second direction.

[0020] Optionally, when multiple strip electrodes are used to control the propagation path of light in a multimode waveguide, the number of electrodes used simultaneously is ≥2, and different combinations of electrode power can achieve different light propagation path control. The length and area of ​​the multiple strip electrodes in the first and second directions are not limited, ensuring free control of light.

[0021] Secondly, an optical scanning device cascade component is provided, comprising: multiple planar cascades and three-dimensionally integrated optical switch-type optical scanning devices as provided in the first aspect above. The specifications of the different optical switch-type scanning devices can be the same or different; that is, the multimode waveguide length, width, electrode configuration, number of output waveguides, and angle with the normal to the output plane included in the different optical switch-type scanning devices can be the same or different.

[0022] In summary, this application provides an integrated optical switch type optical scanning device. This optical scanner adopts a planar waveguide structure, and the propagation path of the light field in the multimode waveguide can be modulated through multiple strip electrodes. Light can be selectively guided to the output waveguide with different bending angles to achieve optical scanning. Furthermore, this integrated optical switch type optical scanning device is fabricated from an optical waveguide material with thermo-optical effects. Light can be emitted from the end face of the output waveguide without special treatment, and large-angle scanning is achieved through end-face refraction. This optical switch type optical scanner can effectively reduce design difficulty and manufacturing costs, achieve on-chip large-angle, high-precision optical scanning, and has no limitation on the operating range of the input wavelength. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention.

[0024] Figure 1 This is a schematic diagram of the structure of an optical switch-type scanning device provided in an embodiment of this application;

[0025] Figure 2 yes Figure 1 The cross-sectional view of the optical switch-type scanning device shown is along the first direction x;

[0026] Figure 3 yes Figure 1 The cross-sectional view of the optical switch-type scanning device shown is along the second direction y.

[0027] Figure 4 This is a simulation result diagram of the electrode heating temperature gradient of the optical switch type scanning device provided in the embodiments of this application;

[0028] Figure 5 This is a simulation result diagram of the refractive index gradient of the electrode heating of the optical switch type scanning device provided for the embodiments of this application;

[0029] Figure 6 This is a schematic diagram of light field path modulation under different combinations of heating power provided in the embodiments of this application;

[0030] Figure 7 These are simulation results of light field path modulation under two different combinations of heating power provided for embodiments of this application;

[0031] Figure 8 This is a schematic diagram of light refraction at the light exit end face provided in an embodiment of this application;

[0032] Figure 9 This is a schematic diagram of the tapered and multimode waveguide structure at the optical emission end face provided in the embodiments of this application;

[0033] Figure 10 This is a simulation result diagram of the refraction of light at the light exit end face provided for the embodiments of this application;

[0034] Figure 11 This is a graph showing the calculated light emission angle and light transmittance at different incident angles, provided for the embodiments of this application.

[0035] Figure 12 This is a schematic diagram of an exemplary embodiment provided in this application.

[0036] Figure 13 This is a schematic diagram of another exemplary embodiment provided for the present application.

[0037] Figure 14 This is a schematic diagram of a cascaded component structure for an optical scanning device provided in an embodiment of this application. Detailed Implementation

[0038] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. The purpose and effects of the present invention will become clearer. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0039] The integrated optical switch type optical scanning device provided in the embodiments of this application is described in detail below with reference to the accompanying drawings.

[0040] Figure 1 This is a schematic diagram of the structure of the integrated optical switch type optical scanning device provided in this application example. Figure 2 yes Figure 1 The image shows a cross-sectional view of the optical scanner along the first direction x. Figure 3 yes Figure 1 The image shows a cross-sectional view of the optical scanner along the second direction y.

[0041] refer to Figure 1 The integrated optical switch type optical scanning device includes an input waveguide 10, a multimode waveguide 20, and multiple arbitrarily bendable output waveguides 30. The input waveguide 10, multimode waveguide 20, and multiple arbitrarily bendable output waveguides 30 are arranged along a first direction x. The input waveguide 10 is connected to the input end of the multimode waveguide 20, and the multiple arbitrarily bendable output waveguides 30 are connected to the output end of the multimode waveguide 20. The multiple output waveguides can be bent according to the design to form different emission angles with the output end face 40 of the integrated optical switch type optical scanning device. The output end face 40 can be any one of the four sides of the waveguide chip, thereby achieving scanning over a large angle range of 360°. The input waveguide 10, multimode waveguide 20, and multiple arbitrarily bendable output waveguides 30 are made of optical waveguide materials with thermo-optical effects, such as polymers, silicon dioxide, silicon, indium phosphide, etc.

[0042] In this embodiment, to reduce coupling loss, the input waveguide 10 may include an input straight waveguide 101 and an input wedge waveguide 102. The wider end of the input wedge waveguide 102 is connected to the input end of the multimode waveguide 20, and the narrower end of the input wedge waveguide 102 is connected to one end of the input straight waveguide 101. The other end of the input straight waveguide 101 is connected to an external optical fiber. Alternatively, the input waveguide may also include another wedge waveguide connected to the end of the input straight waveguide 101 furthest from the input wedge waveguide 102; that is, the input waveguide 10 may include multiple wedge waveguides, with adjacent wedge waveguides connected by a straight waveguide. This embodiment does not limit the structure of the input waveguide, as long as mode matching is maximized and loss is minimized.

[0043] refer to Figure 2 and Figure 3The integrated optical switch type optical scanning device includes multiple strip electrodes 50, which are positioned directly above the multimode waveguide 20 along the first direction x. The waveguide chip includes a silicon substrate 90, a second cladding layer 80, a first core layer 70, and a first cladding layer 60 arranged sequentially upwards along the third direction z. The input waveguide 10, the multimode waveguide 20, and multiple arbitrarily bendable output waveguides 30 are all located within the first core layer 70. Figure 3 As shown, multiple strip electrodes 50 are arranged along the second direction y to control the propagation path of the optical field in the multimode waveguide. The second direction y is perpendicular to the first direction x, and the third direction z is perpendicular to both the first direction x and the second direction y.

[0044] The working principle of the integrated optical switch type optical scanning device provided in this application is as follows: the optical switch switching function is achieved by adjusting the thermooptical adjustable waveguide lens (TOWL); the output waveguide can be bent at any different angle through geometric design, and the end face refraction is used to expand the end face refraction angle to achieve a large angle range scanning function. The two working principles mentioned above are explained below.

[0045] These multiple strip electrodes, by applying current or voltage, alter the refractive index distribution of the first core layer 70, the first cladding layer 60, and the second cladding layer 80, thereby directly changing the overall temperature gradient distribution of the multimode waveguide 20. Figure 4 As shown. It can be understood that by adjusting two or more electrodes, the refractive index distribution in the yz plane of the multimode waveguide region can be made to exhibit a quadratic parabolic curve distribution, such as... Figure 5 As shown.

[0046] It is understandable that the above methods of changing the refractive index distribution are based on the thermo-optical effect. Other methods of changing the refractive index are also applicable.

[0047] Similar to lenses and graded-index fibers, multimode waveguides based on quadratic refractive index distributions can also achieve focusing imaging. In this application example, by using different combinations of electrode power, different equivalent lens parameters can be flexibly adjusted and switched to achieve imaging functions at different positions, which is called a thermo-optical tunable waveguide lens (TOWL). Therefore, the input light field can be imaged onto different y directions in the same x-direction, realizing an optical switching function, such as... Figure 6As shown in the diagram, imaging propagation path 100 represents one possible electrode power combination adjustment result, and imaging propagation path 110 represents another possible electrode power combination adjustment result. It can be understood that by using different electrode power combinations, the imaging propagation path of the optical field in the multimode waveguide can be changed, thereby guiding the input light to different output ports and realizing the function of an optical switch. Furthermore, the imaging propagation paths guiding light to the same port can also be different; for example, it can be through imaging propagation path 110 or imaging propagation path 120. Figure 7 The simulation results show the light field path modulation under two different heating power combinations.

[0048] The propagation of the light field emitted from the output port is as follows Figure 8 As shown in the diagram. Here, θ1 is the angle between the optical field passing through the output waveguide and the 40° normal to the waveguide end face of the optical scanning device, also known as the input angle; θ2 is the angle between the emitted optical field and the 40° normal to the waveguide end face, also known as the output angle. θ1 and θ2 satisfy Snell's law: n1sinθ1=n2sinθ2, where n1 is the effective refractive index of the mode at the output end of the output waveguide, and n2 is the refractive index of the output scan free space.

[0049] like Figure 1 As shown, in this embodiment, the arbitrarily bendable output waveguide includes an output wedge waveguide 301 and several straight waveguides and curved waveguides 302 connected in series. The wider end of the output wedge waveguide 301 is connected to the output end of the multimode waveguide 20, and the narrower end of the output wedge waveguide 301 is connected to the straight waveguide or curved waveguide 302 to reduce coupling loss. The several straight waveguides and curved waveguides connected in series are designed as needed to achieve the required scanning angle and position. This embodiment does not impose specific limitations on the structure of the arbitrarily bendable output waveguide, as long as it satisfies Snell's law.

[0050] As one example, when n1 is 1.457 and n2 is 1, the simulation verification results are as follows: Figure 9 As shown, when light travels from an optically denser medium to an optically less dense medium, it is refracted at a larger angle.

[0051] like Figure 10As shown, the last section of the output waveguide 30, which can be bent arbitrarily, near the waveguide end face of the optical scanning device, can adopt a multimode waveguide or tapered waveguide structure to control the size of the near-field output spot, thereby reducing the far-field divergence angle and achieving directional emission of approximately plane waves within a certain distance range. For example, using a tapered waveguide structure, the width of the output waveguide can be designed from 3.5μm to 0.1μm by reverse tapering. At this time, the spot size approaches infinity, and directional emission of approximately plane waves can be achieved. This flexibility allows the system to meet the optical performance requirements of different application scenarios. The transmittance at different exit angles can be calculated using Fresnel's formula, such as... Figure 11 As shown. By selecting the output polarization state of the laser as TE (TE is the output polarization state of most lasers), a transmission efficiency of over 80% and low energy loss can be achieved within a horizontal single-sided output angle range of approximately ±80°. Furthermore, because this scanning device operates independently of wavelength, dispersive elements, such as prisms, can be added in the vertical direction to achieve vertical angle scanning by emitting light of different wavelengths.

[0052] It is understood that the optical scanning device provided in this application example controls the output angle θ2 by geometrically designing the angle θ1, and then switches different output waveguides by optical switches to realize optical scanning functions at different angles.

[0053] For example, such as Figure 12 As shown, an embodiment of an integrated optical switch type optical scanning device is provided, with the scanning range concentrated on one side of the waveguide chip.

[0054] For example, such as Figure 13 As shown, another embodiment of an integrated optical switch type optical scanning device is provided, which extends the scanning range to all four sides of the waveguide chip.

[0055] For example, such as Figure 14 As shown, an embodiment of a cascaded optical scanning device is provided. Certain output waveguides of an integrated optical switch type optical scanning device are connected to the input waveguides of another integrated optical switch type optical scanning device. Because the output waveguides are arbitrarily bendable, the cascaded component can arrange the specific connections and positions of each integrated optical switch type optical scanning device according to the required scanning location and range.

[0056] In summary, this application provides an integrated optical switch-type optical scanning device. This optical scanner employs a planar waveguide structure, and multiple strip electrodes can modulate the propagation path of the light field in the multimode waveguide, selectively guiding light into output waveguides with different bending angles to achieve optical scanning. Since the output waveguide end face does not require special processing to emit light, and large-angle scanning is achieved through end face refraction, this optical switch-type optical scanner can effectively reduce design difficulty and manufacturing costs, achieving on-chip large-angle, high-precision optical scanning.

[0057] In the embodiments of this application, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "at least one" refers to one or more, and "multiple" refers to two or more.

[0058] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects are in an "or" relationship. The above descriptions are merely optional embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An integrated optical switch type optical scanning device, characterized in that, include: One input waveguide, one multimode waveguide, multiple arbitrarily bendable output waveguides, and multiple strip electrodes; The input waveguide, the multimode waveguide, and the plurality of arbitrarily bendable output waveguides are arranged along a first direction, and the input waveguide is connected to the input end of the multimode waveguide, and the plurality of arbitrarily bendable output waveguides are connected to the output end of the multimode waveguide. Multiple strip electrodes are positioned directly opposite the multimode waveguide and are spaced apart along a second direction perpendicular to the first direction; Multiple strip electrodes are used to modulate the propagation path of the optical field in the multimode waveguide, thereby selectively guiding light into the output waveguide with different bending angles; The input waveguide, multimode waveguide, and multiple arbitrarily bendable output waveguides are made of optical waveguide materials with thermo-optic effects; The angle between the optical field of the output waveguide and the normal to the waveguide end face of the optical scanning device is defined as follows: θ 1. The angle between the emitted light field from the end face and the normal to the waveguide end face of the optical scanning device is . θ 2, then θ 1 and θ 2. Satisfies: n 1sin θ 1= n 2sin θ 2 in, n 1 represents the effective refractive index of the mode at the output end of the output waveguide. n 2 represents the refractive index of the output scan free space.

2. The integrated optical switch type optical scanning device according to claim 1, characterized in that, The arbitrarily bendable output waveguide includes an output wedge waveguide and several straight waveguides and curved waveguides connected in series. The wider end of the output wedge waveguide is connected to the output end of the multimode waveguide, and the narrower end of the output wedge waveguide is connected to the straight waveguide or curved waveguide.

3. The integrated optical switch type optical scanning device according to claim 1, characterized in that, The last section of the output waveguide, which can be bent arbitrarily, near the waveguide end face of the optical scanning device is designed as a multimode waveguide or a tapered waveguide structure to control the size of the near-field output spot, thereby reducing the far-field divergence angle.

4. The integrated optical switch type optical scanning device according to claim 1, characterized in that, The input waveguide includes an input wedge waveguide, the wider end of which is connected to the input end of the multimode waveguide.

5. The integrated optical switch type optical scanning device according to claim 4, characterized in that, The input waveguide further includes an input straight waveguide, which is connected to the end of the input wedge waveguide away from the multimode waveguide.

6. The integrated optical switch type optical scanning device according to any one of claims 1 to 5, characterized in that, The input waveguide, multimode waveguide, and multiple arbitrarily bendable output waveguides are all located in the first core layer.

7. The integrated optical switch type optical scanning device according to claim 6, characterized in that, The integrated optical switch type optical scanning device further includes: a first cladding layer and a second cladding layer; the first core layer is located between the first cladding layer and the second cladding layer, and a plurality of strip electrodes are located on the side of the first cladding layer away from the first core layer; wherein, the refractive index of the first core layer is greater than the refractive index of the first cladding layer and the second cladding layer.

8. The integrated optical switch type optical scanning device according to claim 1, characterized in that, It also includes a dispersive element disposed in the third direction to realize angular scanning of the third direction; the third direction is simultaneously perpendicular to the first direction and the second direction.

9. A cascaded component for optical scanning devices, characterized in that, The cascaded optical scanning device components include: multiple planar cascaded and three-dimensionally integrated optical switch type optical scanning devices as described in any one of claims 1 to 7.

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