Etching-free optical waveguide based on novel continuous bound state and dispersion regulation and control method

Abstract

The invention discloses an etching-free optical waveguide based on a novel continuous bound state and a dispersion regulation and control method, and belongs to the field of integrated optoelectronics. The etching-free optical waveguide sequentially comprises a waveguide cladding, a low-emissivity flat plate layer, an optical waveguide layer, an oxidation buried layer and a substrate from top to bottom; the widths and the lengths of the optical waveguide layer, the oxide buried layer and the substrate are the same; and the waveguide cladding is formed by combining a plurality of strip-shaped structures. The etching-free optical waveguide does not need a complex etching process, reduces the manufacturing cost, reduces the process errors and defects, simplifies the manufacturing process, has the characteristic of low loss, and facilitates the development of ultra-low-loss waveguide devices. According to the dispersion control method, the dispersion control of the mode can be realized under the condition that the morphology of the optical waveguide is not changed by using ion beam etching and photoetching processes, and the development of a high-performance on-chip nonlinear device is facilitated.

Description

Technical Field

[0001] The invention belongs to the field of integrated optoelectronics, and in particular relates to an etching-free optical waveguide and a dispersion control method. Background Art

[0002] The silicon platform has the characteristics of high refractive index and high nonlinear refractive index, and is an ideal material platform for the development of high-density integrated nonlinear devices. Dispersion, as one of the core factors affecting the performance of nonlinear devices, directly affects the bandwidth and energy conversion efficiency of the device. For example, in the research and development of the cutting-edge technology of Kerr optical frequency comb, the range of the anomalous dispersion region is particularly critical. It directly limits the bandwidth that the Kerr optical frequency comb can achieve, thereby affecting its application capabilities in optical communications, spectral analysis, and quantum information processing. By regulating the geometric morphology of the waveguide, such as adjusting the width, height, and sidewall inclination of the waveguide, the dispersion characteristics of the waveguide can be effectively controlled. However, previous dispersion control is based on changing the morphology of the waveguide. The waveguide is developed by etching or photolithography. The process is complex and will introduce scattering losses caused by the roughness of the waveguide sidewalls, which in turn affects the performance of the nonlinear device.

[0003] Researchers have conducted extensive research on dispersion control by changing the waveguide morphology through etching. In terms of papers, in 2010, Zhang Lin et al. from the University of Southern California proposed a silicon slit waveguide that produces a flat dispersion of 0±16ps / nm / km in the 553nm wavelength range (Optics Express, 18, 19, 20529). In 2016, Hanxiao Liang et al. from the University of Rochester proposed double-cladding and multi-cladding waveguide structures that can flexibly control group velocity dispersion over a spectral range spanning multiple octaves (Optics Express, 24, 26, 29444). In 2019, Yuhao Guo et al. from Tianjin University proposed a new type of dispersion flattening technology that can produce ultra-flat group velocity dispersion curves with 5 and 6 zero-dispersion wavelengths (Photonics Research, 7, 11, 1279). However, all of the above studies changed the morphology of the waveguide through ion beam etching or photolithography to control dispersion, which is a complex process and will introduce scattering losses.

[0004] In terms of patents, in 2017, Chen Minghua and others from Tsinghua University used the mode coupling principle to adjust the width interval between waveguide cores to control dispersion and applied for a Chinese invention patent (201710525571.0). In 2020, Cheng Zhenzhou and others from Tianjin University invented a convex multimode waveguide, which controls the geometric appearance of the waveguide to make the TE0 mode and TE1 mode have similar dispersion curves, and applied for a Chinese invention patent (202010623165.X). However, in the above patents for waveguide dispersion control, photolithography or ion beam etching is also used to change the waveguide morphology.

[0005] In summary, although dispersion control in waveguides has been widely studied, previous studies have all achieved dispersion control by changing the waveguide morphology through ion beam etching or photolithography. The manufacturing process is complex and expensive, and the roughness of the waveguide sidewalls will affect the waveguide transmission loss, which to a certain extent limits the development of high-performance nonlinear waveguide devices. Summary of the invention

[0006] In order to solve the limitation of the development and application of optical parametric devices caused by the existing dispersion control technology that requires the use of ion beam etching or photolithography to change the morphology of the waveguide, the present invention proposes an etching-free optical waveguide and dispersion control method based on a new continuous bound state.

[0007] The present invention is achieved through the following technical solutions:

[0008] A novel continuous bound state-based etching-free waveguide comprises, from top to bottom, a waveguide cladding 1, a low-emissivity slab layer 2, an optical waveguide layer 3, an oxide buried layer 4 and a substrate 5; the width and length of the optical waveguide layer 3, the oxide buried layer 4 and the substrate 5 are the same; the waveguide cladding 1 is composed of a plurality of strip structures.

[0009] Furthermore, the material of the waveguide cladding 1 is a layered combination of one or more materials selected from silicon dioxide, silicon nitride and polymer.

[0010] Furthermore, the material of the low-emissivity flat layer 2 is a layered combination of one or more materials selected from silicon dioxide, silicon nitride, and polymer.

[0011] Furthermore, the material of the optical waveguide layer 3 is composed of one material or a plurality of materials selected from the group consisting of silicon, germanium, a silicon-germanium mixture, silicon nitride, indium phosphide, gallium arsenide, lithium niobate, indium gallium arsenide, and aluminum gallium arsenide in layers.

[0012] Furthermore, the waveguide cladding 1 is made by magnetron sputtering, ion beam sputtering, chemical vapor deposition, thermal oxidation or gel-sol method.

[0013] Furthermore, the low-emissivity flat layer 2 is made by magnetron sputtering, ion beam sputtering, chemical vapor deposition, thermal oxidation or gel-sol method.

[0014] On the other hand, the present invention provides a novel dispersion control method for a continuous bound state etch-free optical waveguide, which realizes dispersion control for the spatial mode inside the continuous bound state etch-free optical waveguide by controlling the geometric morphology of the waveguide cladding and the low refractive index planar layer structure.

[0015] Compared with the prior art, the advantages of the present invention are as follows:

[0016] (1) The dispersion control method of the present invention can achieve dispersion control of the mode without using ion beam etching and photolithography processes to change the morphology of the optical waveguide, which is helpful for the development of high-performance on-chip nonlinear devices.

[0017] (2) The manufacturing process of the device of the present invention is fully compatible with the existing CMOS process, which is conducive to the large-scale mass production of the device.

[0018] (3) The optical waveguide manufacturing of the present invention does not require a complex etching process, which reduces manufacturing costs, reduces process errors and defects, and simplifies the manufacturing process.

[0019] (4) The waveguide structure developed by the present invention has the characteristic of low loss, which is conducive to the development of ultra-low loss waveguide devices.

[0020] (5) The waveguide structure of the present invention can be applied to a variety of optical functional materials, providing greater flexibility and selection space for the design of integrated optical chips, and can meet the needs of optical devices of different sizes and shapes. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0022] Figure 1 This is a schematic diagram of the continuous bound state etching-free optical waveguide structure of the present invention;

[0023] Figure 2 Material dispersion curves for silicon, silicon dioxide, and silicon nitride;

[0024] Figure 3 The dispersion curve of TM0 mode when the waveguide cladding width is 0.8μm, the waveguide cladding thickness is 0.1μm, the low refractive index slab width is 2.8μm, and the low refractive index slab thickness is 0.2μm;

[0025] Figure 4 This is the dispersion curve of the TM0 mode when the waveguide cladding width is 1.2μm, the waveguide cladding thickness is 0.1μm, the low-refractive-index slab width is 4.2μm, and the low-refractive-index slab thickness is 0.3μm. DETAILED DESCRIPTION

[0026] In order to clearly and completely describe the technical solution and its specific working process of the present invention, the specific implementation methods of the present invention are as follows in conjunction with the accompanying drawings of the specification:

[0027] Example 1

[0028] like Figure 1 As shown, this embodiment provides an etching-free optical waveguide based on a continuous bound state, which includes a waveguide cladding 1, a low-emissivity slab layer 2, an optical waveguide layer 3, an oxide buried layer 4 and a substrate 5 from top to bottom, and the waveguide cladding 1 is composed of a plurality of strip structures.

[0029] The above-mentioned continuous bound state etch-free optical waveguide can control the dispersion of the spatial mode by changing the shape of the waveguide cladding and the low refractive index slab layer. First, a set of structural size parameters of the waveguide cladding and the low refractive index slab layer are designed, including the waveguide cladding width W1, the waveguide cladding thickness H1, the low refractive index slab layer width W2, and the low refractive index slab layer thickness H2, and the dispersion curve of the spatial mode is calculated according to the second-order derivative of the effective refractive index of the waveguide mode in the continuous bound state etch-free optical waveguide; then, by adjusting one or more parameters among the waveguide cladding width W1, the waveguide cladding thickness H1, the low refractive index slab layer width W2, and the low refractive index slab layer thickness H2, the dispersion control of the spatial mode is achieved.

[0030] To further illustrate the proposed technology, the present invention utilizes the commercial software tool COMSOL Multiphysics, a finite element method mode solver based on the beam propagation method, to simulate the effective refractive index of the optical waveguide, and then calculates the group velocity dispersion curve based on the simulation results.

[0031] like Figure 1As shown, the selected waveguide cladding is a strip structure, the waveguide cladding material is silicon nitride material, the low refractive index slab layer is a rectangular structure, the low refractive index slab layer material is silicon nitride, the optical waveguide material is silicon material, the oxide buried layer material is silicon dioxide material, the waveguide layer thickness is 220nm, and the oxide buried layer thickness is 3μm. The commercial software COMSOL Multiphysics is used to calculate the effective refractive index of TM0, and the dispersion of TM0 is calculated using Matlab software using formula (1). In this embodiment, the waveguide cladding width is 0.8μm, the waveguide cladding thickness is 0.1μm, the low refractive index slab layer width is 2.8μm, and the low refractive index slab layer thickness is 0.2μm. The effective refractive index of the TM0 mode from 1.2μm to 1.7μm is calculated, and then the dispersion curve of the TM0 spatial mode is calculated using formula (1). The results are shown in Figure 3 The group velocity dispersion of the TM0 mode has multiple peaks and troughs in the range of 1.32μm to 1.7μm, providing a variety of wavelength options for the development of nonlinear devices.

[0032] Example 2

[0033] like Figure 1 As shown, the selected waveguide cladding is a strip structure, the waveguide cladding material is silicon nitride material, the low refractive index slab layer is a rectangular structure, the low refractive index slab layer material is silicon nitride material, the optical waveguide material is silicon material, the oxide buried layer material is silicon dioxide material, the waveguide layer thickness is 220nm, and the oxide buried layer thickness is 3μm. The commercial software COMSOL Multiphysics is used to calculate the effective refractive index of TM0, and the dispersion of TM0 is calculated by Matlab software using formula (1). In this embodiment, the waveguide cladding width is 1.2μm, the waveguide cladding thickness is 0.1μm, the low refractive index slab layer width is 4.2μm, and the low refractive index slab layer thickness is 0.3μm. The effective refractive index of the TM0 mode at 1.2μm to 1.7μm is calculated respectively, and then the dispersion curve of the TM0 spatial mode is calculated using formula (1). The results are shown as follows: Figure 4 As shown in Figure 2, the group velocity dispersion curve of TM0 changes around -5000ps / nm / km, achieving the regulation of the spatial mode.

[0034] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0035] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0036] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. An etching-free waveguide based on a novel continuous bound state, characterized in that: The optical waveguide layer (3), the buried oxide layer (4) and the substrate (5) are sequentially comprised from top to bottom; the width and length of the optical waveguide layer (3), the buried oxide layer (4) and the substrate (5) are the same; and the waveguide layer (1) is composed of a plurality of strip structures.

2. The etching-free waveguide based on a novel continuous bound state as claimed in claim 1, characterized in that: The material of the waveguide cladding (1) is one or a layered combination of multiple materials selected from silicon dioxide, silicon nitride and polymer.

3. The etching-free waveguide based on a novel continuous bound state as claimed in claim 1, characterized in that: The material of the low-emissivity flat plate layer (2) is one or a layered combination of multiple materials selected from silicon dioxide, silicon nitride and polymer.

4. The etching-free waveguide based on a novel continuous bound state as claimed in claim 1, characterized in that: The material of the optical waveguide layer (3) is one material selected from the group consisting of silicon, germanium, a silicon-germanium mixture, silicon nitride, indium phosphide, gallium arsenide, lithium niobate, indium gallium arsenide, and aluminum gallium arsenide, or a plurality of materials are layered.

5. The etching-free waveguide based on a novel continuous bound state as claimed in claim 1, characterized in that: The waveguide cladding (1) is manufactured by magnetron sputtering, ion beam sputtering, chemical vapor deposition, thermal oxidation or gel-sol method.

6. The etching-free waveguide based on a novel continuous bound state as claimed in claim 1, characterized in that: The low-emissivity flat layer (2) is manufactured by magnetron sputtering, ion beam sputtering, chemical vapor deposition, thermal oxidation or gel-sol method.

7. The novel dispersion control method of continuous bound state etching-free optical waveguide according to claim 1, characterized in that: The dispersion control is achieved by controlling the geometric morphology of the waveguide cladding and the low-refractive index slab layer structure to achieve dispersion control for the spatial mode inside the continuous bound state etch-free optical waveguide.

Images