Optimization of long-period grating inscribed in large mode area photonic crystal fiber for design of bandstop filter

Abstract

By inscribing long period grating (LPG) in a photonic crystal fiber (PCF), optical filters for communication wavelengths can be fabricated. In this paper, by utilizing coupled-mode theory and enhanced improved vectorial effective index method, a design of bandstop filter based on optimal LPG parameters is presented where the optimized full-width half-maximum (FWHM), the number ( N) and total length of gratings of LPGs ( L) are determined. As a result, by the determination of optimized LPG parameters with an optimum length of L opt=6.5 mm and optimum number of grating N opt=27 inscribed in the PCF, a bandstop optical filter with FWHM=1 nm is designed.