Orbital angular momentum mode multiplexing and demultiplexing coupler based on microstructure optical fiber

Abstract

The invention discloses an orbital angular momentum mode multiplexing and demultiplexing coupler based on a microstructure optical fiber. The orbital angular momentum mode multiplexing and demultiplexing coupler comprises a middle annular fiber core which supports N orbital angular momentum mode transmission in a waveband with a given central wavelength lambda, a background material, and n single-mode fiber cores which only support fundamental mode transmission and are distributed around the annular fiber core, n=2N, and the single-mode fiber cores are divided into N pairs. The refractive indexes of the single-mode fiber cores and the annular fiber core are higher than that of the background material. The radiuses of the two single-mode fiber cores in each pair of single-mode fiber cores,refractive index differences between the two single-mode fiber cores and the background material and distances between the two single-mode fiber cores and the annular fiber core are equal, included angles between the two single-mode fiber cores and a center of the coupler is (2m + 1) pi / 2l, m = 0, 1, 2...(l1), and l is orders of orbital angular momentum modes of the single-mode fiber cores coupledto middle annular fiber core. According to the orbital angular momentum mode multiplexing and demultiplexing coupler, N pairs of single-mode signals in the single-mode fiber cores are multiplexed toN orbital angular momentum modes in the middle annular fiber core, the mode division multiplexing is realized, and so the transmission capacity of an optical fiber communication system is increased.

Description

technical field [0001] The invention relates to an orbital angular momentum mode multiplexing and demultiplexing coupler based on a microstructure optical fiber, which is used for realizing multiplexing of multiple orbital angular momentum modes and has important application value in a space division multiplexing transmission system. Background technique [0002] In recent years, bandwidth-consuming services such as mobile Internet, Internet of Things, and cloud computing data centers have been increasing, posing huge challenges to existing communication systems. Therefore, how to continuously improve the capacity of the communication system to meet the ever-increasing demand for communication capacity has become an urgent problem to be solved in optical communication. In recent years, the methods to solve this problem mainly include multiplexing technologies such as wavelength division multiplexing, time division multiplexing, offset division multiplexing, and orthogonal fr...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention: the orbital angular momentum mode multiplexer based on the long-period fiber grating and the mode selection coupler needs a high-level In view of the current situation that multiple devices are connected, and the difficulty of making photonic lanterns increases with the number of multiplexing modes, a microstructured optical fiber-based orbital angular momentum mode multiplexing and demultiplexing coupler is proposed.

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