Fabrication and spectral properties of two-dimensional fiber gratings based on LMA fiber

In this paper, the preparation and spectral properties of large mode field double-clad (LMA) fiber two-dimensional fiber gratings are studied. Firstly, a new compact grating analysis model for writing fiber gratings with different periods in different regions of the fiber core is theoretically proposed, and the spectral characteristics of the gratings written in different regions of the fiber core are studied based on the transfer matrix method. A three-wavelength two-dimensional fiber grating with a designed wavelength interval of 1.57 nm was successfully fabricated using a 248 nm excimer laser in a large mode field double-clad fiber laser. The research results show that the spectral characteristics of the two-dimensional fiber grating can be changed flexibly by changing the masking parameters, and the structure is compact. The experimentally obtained two-dimensional fiber grating spectrum is consistent with the theoretical analysis. The research results provide a theoretical reference for the design, fabrication and application of two-dimensional fiber gratings.