Single-core multi-channel moiré fiber grating and multi-wavelength LMA fiber grating fabricated based on two-dimensional spatially encoded phase mask

A two-dimensional optical fiber grating with multi sub-gratings based on a 2D spatially encoded phase mask is designed in this study. The Bragg (FBG) composed of two non-overlapping sub-FBGs, which are laterally separated along the radial direction core. Unlike traditional FBGs, refractive index FBG modulated both axial and directions core, realized by diffraction mask. Compared overlapping grating, can be fabricated at one time to achieve multi-wavelength output, its compact structure provides new idea for multiplexing. As examples, single-core multi-channel moiré three subgratings single-mode LMA fiber, respectively. Using improve modulation from one- two- or even three-dimensions, helpful precise manipulation complex field fiber.