A tunable optical filter based on a photonic integrated chip

Abstract

This invention belongs to the field of integrated optics and optical communication, and specifically relates to a tunable optical filter based on a photonic integrated chip. The filter is implemented using a reservoir chip, which includes an input layer (1), a reservoir layer (2), and a readout layer (3). The input layer consists of a grating (1-1) and a 1×2 multimode interferometer (1-2). The reservoir layer is a quincunx network formed by directional couplers (2-1) and waveguides (2-2). The readout layer includes an optical modulator (3-1) and a 2×1 multimode interferometer (3-2). Miniature thermoelectrodes (2-3, 3-3) are fabricated on the reservoir waveguide and optical modulator. A particle swarm optimization (PSO) algorithm is used to train the photonic reservoir with weights, which are then applied to the optical signal for fitting. The signal is output through an optical amplifier (3-4) and then exported from the chip via a grating (3-5). This tunable optical filter combines a reservoir structure with a PSO algorithm for full-domain training, greatly improving the flexibility of the optical filter.

Description

Technical Field

[0001] This invention belongs to the field of integrated optics and optical communication. In particular, it relates to a tunable optical filter based on a photonic integrated chip. Background Technology

[0002] In modern optical communication systems, tunable optical filters have become indispensable optical devices. Tunable optical filters allow only specific wavelength signals to pass through, while other wavelength signals are not output, and the wavelength of the output optical signal can be adjusted as needed. They can be widely used in wavelength division multiplexing optical communication, optical cross-connect systems, and microwave photonic signal shaping, among other applications. Currently, tunable optical filters are based on structures such as micro-ring resonators, Mach-Zehnder interferometers, and ring-assisted Mach-Zehnder interferometers, which suffer from poor filtering stability and a limited filtering spectrum. Thanks to the rapid development of chip-integrated optoelectronic device fabrication technology, integrated optical filter chips are no less capable than traditional discrete optoelectronic devices in terms of performance. Integrated optical filter structures have advantages such as small size, high stability, low power consumption, and mass production capability. Currently, the design of optical filters using integrated optical reservoirs is still in its infancy. Therefore, to improve the flexibility of filtering systems and achieve algorithmic control of filter parameters, integrated photonic reservoirs have become the core architecture. Summary of the Invention

[0003] To address the problems of existing technologies, the present invention aims to propose a tunable optical filter based on a photonic integrated chip. This filter features improved flexibility through algorithmic control.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] In a first aspect, this invention provides a tunable optical filter based on a photonic integrated chip, comprising a photonic reservoir integrated chip. The photonic reservoir integrated chip consists of an input layer, a reservoir layer, and a readout layer. The input layer is composed of a 2×1 multimode interferometer; the reservoir layer is composed of a directional coupler and a waveguide, connected according to a helical topology to form a quincunx network; the readout layer is composed of an optical modulator and the 2×1 multimode interferometer, with miniature thermoelectrodes fabricated on the upper arms of the waveguide and optical modulator. By adjusting the device parameters, the filter achieves a tunable center wavelength and a controllable free spectral range.

[0006] Secondly, this invention proposes an optical filter training algorithm based on a photon reservoir, namely the particle swarm optimization algorithm, which is applied to the photon reservoir readout layer training module. The particle swarm optimization algorithm is an evolutionary computation technique that obtains the optimal training weights by training the amplitude and phase of the optical signals transmitted in the readout layer. The optical modulator assigns values ​​to each optical signal to achieve a flexible filtering function with selectable spectral shape.

[0007] The beneficial effects of this invention are as follows:

[0008] This invention provides a tunable optical filter based on a photonic integrated chip. By adjusting the device parameters in the photonic reservoir, optical signals undergo interference and recombination within the reservoir, forming various new signal types. The readout layer signal is trained across the entire optical domain using a particle swarm optimization algorithm, and the training weights are assigned to each signal for fitting, achieving multiple filtering functions. By adjusting the waveguide parameters in the reservoir, the filter's center wavelength and free spectral range are controllable, effectively improving the flexibility of the optical filter. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of a photon storage pool.

[0010] Figure 2 This is a schematic diagram of the waveguide in a photon reservoir.

[0011] Figure 3 This is a schematic diagram of a directional coupler for a photon reservoir.

[0012] Figure 4 A schematic diagram of a photon reservoir readout layer optical modulator. Detailed Implementation

[0013] The following is in conjunction with the appendix Figure 1-4 A tunable optical filter based on a photonic integrated chip is further described.

[0014] This invention provides a tunable optical filter based on a photonic integrated chip, such as... Figure 1 As shown, the tunable optical filter is based on a photonic reservoir integrated chip. The photonic reservoir integrated chip consists of an input layer (1), a reservoir layer (2), and a readout layer (3). The input layer consists of a grating (1-1) and a 1×2 multimode interferometer (1-2). The reservoir layer consists of a directional coupler (2-1) and a waveguide (2-2), which are connected according to a spiral topology to form a quincunx network. The readout layer consists of an optical modulator (3-1) and a 2×1 multimode interferometer (3-2), and miniature thermoelectrodes (2-3, 3-3) are fabricated on the waveguide and the optical modulator. By adjusting the device parameters, the filter can achieve flexible filtering functions with adjustable center wavelength, controllable free spectral range, and selectable spectral shape.

[0015] Figure 2 This is a schematic diagram of the photon reservoir waveguide provided by the present invention, as shown below. Figure 2 As shown, the waveguide has two ports with a phase difference between them. The main parameters of the waveguide are its length and refractive index.

[0016] Figure 3 A schematic diagram of the photon reservoir directional coupler provided by the present invention is shown below. Figure 3 As shown, the directional coupler has 4 ports, including a through port and a cross port. The main parameter of the directional coupler is the splitting ratio.

[0017] Figure 4 A schematic diagram of the photon reservoir readout layer optical modulator provided by the present invention is shown below. Figure 4 As shown, the optical modulator has two ports, and the upper and lower arms can be set with different phase values. The main parameter of the optical modulator is the phase difference between the upper and lower arms.

[0018] The filtering principle of the optical filter is described as follows: Incident light is introduced into the photon reservoir chip through the grating coupler (1-1). After passing through the input layer (1), the optical signal is evenly divided into 4 paths and input into the reservoir (2). The signal is transmitted in the reservoir according to the spiral topology of the directional coupler (2-1) and the waveguide (2-2). Optical interference occurs at the directional coupler, and the signals of different loops are recombined. The recombined signal is output from the directional coupler on the periphery of the reservoir. The output optical signal enters the readout layer (3) through the waveguide. The optical signal is weighted using an algorithm. Weight values ​​are assigned on the optical modulator (3-1) in the readout layer. The assigned optical signal is fitted and output by a 2×1 multimode interferometer (3-2) and amplified by an optical amplifier (3-4). The optical signal is then exported from the chip by the grating coupler (3-5). By using micro heating electrodes (2-3, 3-3), the relative refractive index of the waveguide in the reservoir and the phase values ​​of the upper and lower arms of the optical modulator in the readout layer are changed, so as to achieve flexible control of the filter parameters. The photon reservoir readout layer is trained in the full optical domain using a particle swarm optimization algorithm to obtain the optimal training weights. These weights are then assigned to the optical modulator to achieve flexible filtering with selectable spectral shapes.

Claims

1. A photonic integrated chip based tunable optical filter, characterized in that, The integrated chip includes a photonic reservoir, comprising an input layer (1), a reservoir (2), and a readout layer (3). The input layer (1) includes a grating (1-1) and a 1×2 multimode interferometer (1-2). The reservoir (2) is composed of multiple directional couplers (2-1) and multiple waveguides (2-2) connected together. The multiple directional couplers (2-1) and multiple waveguides (2-2) are connected according to a vortex topology to form a quincunx network, so that the input optical signal interferes at the directional couplers in the reservoir (2) and recombines between different loops. The readout layer (3) includes multiple optical modulators (3-1) and a 1×2 multimode interferometer (1-2). 3-2), the output optical signal of the reservoir (2) enters the readout layer (3) through the waveguide, and after being weighted on the optical modulator (3-1), it is fitted and output by the 1×2 multimode interferometer (3-2); the waveguide and the optical modulator are respectively provided with micro thermoelectrodes (2-3, 3-3), the micro thermoelectrodes are used to change the relative refractive index of the waveguide in the reservoir and the phase value of the upper and lower arms of the optical modulator; the readout layer (3) is trained in the full optical domain using the particle swarm optimization algorithm to obtain training weights for amplitude and phase modulation of each output optical signal, thereby realizing adjustable center wavelength of the filter, controllable free spectral range and selectable spectral shape.

2. The photonic integrated chip based tunable optical filter of claim 1, wherein: The reservoir (2) is composed of a directional coupler (2-1) and a waveguide (2-2).

3. The photonic integrated chip based tunable optical filter of claim 1, wherein: The reservoir (2) is connected according to a spiral topology to form a plum blossom-shaped network.

4. The photonic integrated chip based tunable optical filter of claim 1, wherein: The tunable optical filter is trained in the optical domain using a particle swarm optimization algorithm.

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