A few-mode waveguide

Abstract

The invention provides a few-mode waveguide which comprises a waveguide area and a wrapping layer. The wrapping layer comprises a matrix material, first high refractive index of dielectric columns arranged in rectangular grid nodes and a high refractive index of dielectric wrapping layer area positioned at one side of the matrix material; M*M second high refractive index of dielectric columns arranged in rectangular grid nodes and the matrix material surrounding the second high refractive index of dielectric columns form a waveguide area; and the waveguide area supports transmission of at least E21 mode, and the high refractive index of dielectric wrapping layer and the waveguide area are positioned at the two sides of the first high refractive index of dielectric columns respectively. According to the invention, the waveguide of a square structure is used, so that a fundamental mode of the waveguide area is easier to couple with the wrapping mode, the high refractive index of dielectric wrapping layer area destroys the transmission condition of total internal reflection of the wrapping layer mode, high leakage loss is formed, and mode filtering is realized. At the same time, basedon a traditional waveguide transmission principle, a high-order mode of the waveguide area can be limited within the waveguide area effectively, and high-order-mode low-loss transmission can be realized.

Description

technical field The invention relates to the field of communication transmission, in particular to a few-mode waveguide with selective filtering characteristics. Background technique With the continuous development of time division multiplexing, wavelength division multiplexing, polarization multiplexing and other technologies, the communication capacity of single-mode optical fiber is close to its theoretical limit. The method to further improve the communication capacity of a single optical fiber is space division multiplexing technology. Space division multiplexing technology is divided into multi-core fiber multiplexing and mode division multiplexing technology. The mode-division multiplexing (MDM) technology based on few-mode fiber can use each mode in the few-mode fiber as a separate information transmission channel, thereby doubling the communication capacity of the fiber. The key technology of mode division multiplexing is mode converter and mode division multiplex...

AI Technical Summary

Problems solved by technology

A mode converter is a device that converts the fundamental mode in an optical fiber to a higher-order mode or the reverse process. Especially when the fundamental mode is converted to a higher-order mode, it is easy to fail to completely convert the fundamental mode, resulting in the simultaneous transmission of the remaining fundamental mode energy and the higher-order mode. , becomes the crosstalk that affects the optical fiber transmission performance

Engraving long-period fiber gratings on multi-core fibers [Optics Letters, 2015, 40(2): 292-5], the mode conversion efficiency between such fibers is very high, but there are still cases where the mode conversion is not complete

Modulus multiplexers / demultiplexers are also prone to incomplete conversions, causing crosstalk

Some people use asymmetric Y-junction design [OpticsLetters,2014,39(8):2306-9], which effectively improves the conversion efficiency of the multiplexer compared with the traditional structure, but there is still mode crosstalk

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