Optical mode dynamic generation and switching device based on phase change material

Abstract

The invention provides an optical mode dynamic generation and switching device based on a phase-change material, the structure is composed of a double-groove type silicon waveguide, a phase-change material waveguide and a silicon dioxide cladding, the phase-change material waveguide is embedded in the groove type waveguide, and the silicon dioxide cladding covers the outside of the whole structure. By accurately adjusting the crystallinity of the phase change material Sb2S3, the device can dynamically regulate and control the light mode, and conversion from a linear polarization mode to a vortex light mode (an orbital angular momentum mode with topological charges being + 1 or-1) and flexible switching between modes (TE01-TE10) are achieved. The device has the advantages of simple structure, flexible regulation and control, high response speed and the like, and can be widely applied to the fields of optical communication, optical calculation, optical information processing and the like.

Description

(1) Technical Field

[0001] The present invention relates to an optical mode dynamic generation and switching device based on phase change materials, belonging to the fields of photonics and optical communication. (2) Background Art

[0002] In optical communication and photonic integration systems, the orbital angular momentum (OAM) mode can be used to increase the channel capacity due to its orthogonality. In the prior art, the generation of the OAM mode usually relies on a spiral phase plate or a complex fiber structure, which has problems of large volume and poor switching flexibility. In addition, traditional waveguide mode conversion mostly relies on a fixed structure or external mechanical regulation, and it is difficult to achieve dynamic switching. Therefore, there is an urgent need for a miniaturized and dynamically adjustable mode conversion device.

[0003] In recent years, phase change materials have become one of the research hotspots in the field of integrated photonics due to their non-volatile optical properties and nanosecond-level reversible phase change ability. However, the existing optical mode regulation devices based on phase change materials generally have the following technical bottlenecks: high structural complexity, usually relying on multi-level grating or micro-ring resonator structures to achieve mode coupling, resulting in difficulty in compressing the device size; limited regulation freedom, existing schemes mostly focus on single-mode attenuation regulation and cannot achieve dynamic conversion between the fundamental mode and high-order modes; insufficient dynamic conversion performance, especially when realizing real-time switching between the linearly polarized mode and the vortex light mode carrying orbital angular momentum, there are generally problems such as low conversion efficiency and poor mode purity. This severely restricts the practical application of phase change materials in reconfigurable photonic devices.

[0004] In order to further improve the capacity of optical communication systems, researchers have proposed a new communication scheme based on mode division multiplexing (MDM). In mode multiplexing technology, different optical modes can be used as independent communication channels, thereby significantly improving the communication capacity. However, efficient conversion between modes in the prior art is still a technical problem.

[0005] The present invention aims to provide an optical mode dynamic generation and switching device based on phase change materials, and complete the mode conversion of TE 01 →TE 10 and the dynamic switching of the OAM mode with topological charges of ±1. (3) Summary of the Invention

[0006] In the fields of optical computing and optical information processing, the dynamic regulation ability of optical modes is the key to realizing efficient optical logic operations and information processing; the implementation of the present invention includes designing the sizes of the trench waveguide and the phase change material waveguide, and calculating the refractive index changes caused by different crystallinities of Sb2S3. By adjusting the crystallinity of Sb2S3, the optical characteristics of the waveguide can be dynamically changed, thereby realizing the conversion of optical modes. For example, when the input light is TE 01In the [mode name], by adjusting the crystallinity, it can be converted into TE 10 mode or other orbital angular momentum modes.

[0007] The object of the present invention is achieved as follows:

[0008] Shown is a device for dynamic generation and switching of optical modes based on phase change materials, characterized in that: the structure consists of a trench waveguide (1), a phase change material waveguide (2) and a cladding (3); in the device for dynamic generation and switching of optical modes based on phase change materials, the trench size is the same as the phase change material waveguide size, with a length of l = 20.5 μm, a width of w = 0.49 μm, a thickness of h = 0.21 μm, and the material is Sb2S3; the trench waveguide has a length of l = 20.5 μm, a width of W = 1.1 μm, a thickness of H = 1 μm, and the material is silicon; the cladding material is silica.

[0009] Furthermore, when the input is TE 01 mode and the crystallinity is 0.45, when the phase difference of the LP-like mode accumulates to π / 2, the OAM mode with a topological charge of +1 is output; when the crystallinity is 1, the phase difference reaches π, and TE 01 →TE 10 mode conversion is achieved; when the crystallinity is 0.85, the phase difference accumulates to 3π / 2, generating the OAM mode with a topological charge of -1; and when the crystallinity is 0.65, the phase difference is 2π, and the TE 01 mode is still output.

[0010] The trench waveguide adopts a high-contrast Silicon-on-Insulator (SOI) platform, and the waveguide size is designed by strict mode field matching to guide the light beam and provide a specific mode conversion environment.

[0011] The phase change material waveguide is composed of an Sb2S3 thin film prepared by atomic layer deposition, embedded in the trench, and used to dynamically regulate the mode through phase change. At an incident wavelength of 1.55 μm, the refractive index difference Δn between its crystalline state and amorphous state is 0.6.

[0012] The silica cladding covers outside the trench waveguide and the phase change material waveguide, and is used for protection and isolation.

[0013] The beneficial effects of the present invention are as follows:

[0014] The structure of the present invention has the characteristics of being compact and simple, easy to integrate, reducing the manufacturing cost while improving the stability and reliability of the system.

[0015] The present invention only needs to adjust the state of the phase change material to generate different orbital angular momentum modes, with simple operation and fast response speed, and realizes the dynamic regulation of optical modes by dynamically regulating the crystallinity.

[0016] The present invention adopts an all-optical phase change mechanism with a response time < 20 ns, featuring non-volatile dynamic regulation.

[0017] The present invention can generate or switch different optical modes within a fixed length, shortening the device length and enabling integration into existing optical systems. This integratability makes the device highly practical in the fields of on-chip optical interconnection and high-dimensional optical communication. (IV) BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a three-dimensional schematic diagram of the optical mode dynamic generation and switching device based on phase change materials provided by an embodiment of the present invention.

[0019] Figure 2 is the optical field diagram output at l = 20.5 μm when the crystallinity of Sb2S3 is 0.45.

[0020] Figure 3 is the phase diagram output at l = 20.5 μm when the crystallinity of Sb2S3 is 0.45.

[0021] Figure 4 is the optical field diagram output at l = 20.5 μm when the crystallinity of Sb2S3 is 0.65.

[0022] Figure 5 is the phase diagram output at l = 20.5 μm when the crystallinity of Sb2S3 is 0.65.

[0023] Figure 6 is the optical field diagram output at l = 20.5 μm when the crystallinity of Sb2S3 is 0.85.

[0024] Figure 7 is the phase diagram output at l = 20.5 μm when the crystallinity of Sb2S3 is 0.85.

[0025] Figure 8 is the optical field diagram output at l = 20.5 μm when the crystallinity of Sb2S3 is 1, i.e., in the crystalline state.

[0026] Figure 9 is the phase diagram output at l = 20.5 μm when the crystallinity of Sb2S3 is 1, i.e., in the crystalline state. (V) SPECIFIC EMBODIMENTS

[0027] The present invention will be further described in detail below with reference to the drawings and specific examples.

[0028] The specific implementation steps of the present invention include:

[0029] Design the basic structure of the waveguide. Figure 1Shows a three-dimensional structural schematic diagram of a double-groove waveguide: A silicon-based rectangular waveguide is used, with a silica cladding on the surface, and two grooves are etched diagonally on the incident surface of the waveguide along the waveguide propagation direction. An Sb2S3 layer is deposited on the upper surface of the waveguide, and its crystallization state is regulated by thermal or optical pulses. When inputting the TE 01 mode, the grooves designed on the waveguide can break the original rotational symmetry and split the second-order mode in the rectangular waveguide, thereby exciting two orthogonal LP-like eigenmodes with different propagation constants (β1 and β2); when the two LP-like modes have a phase difference of π / 2 or 3π / 2 after passing through different propagation distances, an orbital angular momentum mode with a topological charge of +1 or -1 is further synthesized; when the phase difference between the two LP-like eigenmodes is π, the TE 01 mode is transformed into the TE 10 mode; when the phase difference between the two LP-like eigenmodes is 2π, it is still output in the TE 01 mode; By introducing the phase change material Sb2S3, different phase differences are generated respectively under the same propagation distance through the change of the effective refractive index in the crystalline or amorphous state of Sb2S3, so as to realize the dynamic generation of the orbital angular momentum mode and the conversion between modes at the same propagation distance; The proposed optical mode dynamic generation and switching device is based on a silicon chip with a silica cladding.

[0030] In order to obtain a clear double-lobe pattern in the input waveguide of the orbital angular momentum mode generator, it is necessary to break the symmetry of the square cross-section of the waveguide, and at the same time, the size of the waveguide should be able to support the relevant high-order modes. After calculation, the size of the groove waveguide is selected as W = 1.1 μm and H = 1 μm.

[0031] The equal excitation of the two orthogonal eigenmodes requires special optimization of the groove parameters, two parameters related to the groove, the width w and the height h. The groove width is selected as w = 0.49 μm and the thickness is h = 0.21 μm.

[0032] The groove length is calculated by the formula l = nπ / 2(β1 - β2) (n = 1, 2, 3, 4). Considering that only the state of the phase change material is changed, and an orbital angular momentum mode with a topological charge of +1 or -1 is synthesized at the same propagation distance, the groove length should satisfy that the phase change material generates a phase difference of nπ / 2 (n = 1, 2, 3, 4) in different crystalline states. After calculation, l = 20.5 μm is selected.

[0033] When the crystallinity of Sb2S3 is 0.45, the electric field diagram and phase diagram as shown in Figure 2 and 3 are obtained through simulation.

[0034] When the crystallinity of Sb2S3 is 0.65, the electric field diagram and phase diagram as shown in Figure 4 and 5 are obtained through simulation.

[0035] When the crystallinity of Sb2S3 is 0.85, the electric field map and phase map as shown in Figure 6 and 7 are obtained through simulation.

[0036] When the crystallinity of Sb2S3 is 1, the electric field map and phase map as shown in Figure 8 and 9 are obtained through simulation.

[0037] The present invention is an optical mode dynamic generation and switching device based on phase change materials. The present invention utilizes the refractive index difference of the phase change material Sb2S3 in different crystalline states to dynamically generate orbital angular momentum modes of +1 or -1 and the conversion from the TE 01 mode to the TE 10 mode. It has the advantages of high integration and fast response. Through the combination of trench design and phase change materials, miniaturized and non-mechanical dynamic mode switching is achieved, and it can be applied to high-density optical communication, quantum optics and on-chip photonic processors.

Claims

1. An optical mode dynamic generation and switching device based on phase change materials, characterized in that: This structure consists of a trench waveguide (1), two phase change material waveguides (2), and a cladding layer (3); the phase change material waveguides (2) are arranged inside the trench waveguide (1); the cladding layer (3) covers outside the trench waveguide (1) and the phase change material waveguides (2); in the optical mode dynamic generation and switching device based on phase change materials, the trench size is the same as that of the two phase change material waveguides, with a length of l, a width of w, a thickness of h, and the material is Sb2S3; the trench waveguide has a length of l, a width of W, a thickness of H, and the material is silicon; the cladding material is silica; the operating wavelength of the device is 1.55 μm.

2. The optical mode dynamic generation and switching device based on phase change materials according to claim 1, characterized in that: The length of the phase change material waveguide is l = 20.5 μm, the width is w = 0.49 μm, and the thickness is h = 0.21 μm; the width of the trench waveguide is W = 1.1 μm, and the thickness is H = 1 μm.

3. The optical mode dynamic generation and switching device based on phase change materials according to claim 1, characterized in that: When the working wavelength is 1.55 μm and the crystallinity of the phase change material Sb2S3 is 0.45, the phase difference of the LP-like mode accumulates to π / 2, and the OAM mode with a topological charge of +1 is output; when the crystallinity is 1, the phase difference reaches π, and TE 01 → TE 10 mode conversion is achieved; when the crystallinity is 0.85, the phase difference accumulates to 3π / 2, generating an OAM mode with a topological charge of -1; while when the crystallinity is 0.65, the TE 01 mode is still output.

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