Reverse design method of photon orbital angular momentum mode multiplexer/demultiplexer

Abstract

The invention discloses a reverse design method of a photon orbital angular momentum mode multiplexer / demultiplexer. The method comprises the following steps: setting a plurality of phase plates separated by free space, marking one phase plate as Le, and fixing the phase plate as an equivalent form of an elliptical lens; calculating an inclined plane wave mode formed by reversely propagating an output Gaussian mode to Le and carrying out Le phase modulation, and optimizing the first phase plate to Le by using a wavefront matching method from an OAM mode to the inclined plane wave mode until convergence; releasing restrictions on the phase plates fixed as the elliptical lens, and optimizing all the phase plates by using a wavefront matching method from an OAM mode to a Gaussian mode until convergence; taking the phase shift value phi i of each pixel of all the phase plates as a parameter, taking the weighted average of crosstalk of adjacent orders as an objective function, minimizing the objective function through a steepest descent method, and stopping iteration of the steepest descent method until the maximum crosstalk of the adjacent orders is smaller than or equal to the maximumcrosstalk of non-adjacent orders.

Description

technical field [0001] The invention relates to the technical field of optical communication, and more specifically, to a reverse design method of a photon orbital angular momentum mode multiplexer / demultiplexer. Background technique [0002] With the increasing demand for communication capacity in modern society, and the use of traditional multiplexing dimensions such as amplitude, wavelength, and polarization are gradually approaching the limit, how to use space, a multiplexing dimension that has not been fully utilized, that is, space division multiplexing technology , has attracted the attention of more and more researchers in recent years. Among them, the multiplexing of vortex modes carrying photon orbital angular momentum (OAM, orbital angular momentum) is one of the important research directions. [0003] The mode multiplexing / demultiplexing device is the core device in the mode division multiplexing communication system. It has been demonstrated that a series of p...

AI Technical Summary

Problems solved by technology

[0021] In order to solve the problem that the general reverse design algorithm is easy to fall into local optimum when the degree of freedom is extremely high, the present invention provides a reverse design method of photon orbital angular momentum mode multiplexer / demultiplexer, which Effectively overcome the local optimum in the iterative process, and obtain a high-performance, large-bandwidth OAM mode multiplexer / demultiplexer

Images