Abstract

By using cascaded single-helix helical long-period fibre gratings (SHLPGs) combined with a cladding-mode stripper, a simple and efficient method of production of a polarization-insensitive flat-top band-rejection filter has been proposed and experimentally demonstrated. Unlike the previous SHLPG-based methods in which the obtained spectra are strongly dependent on the polarization status of the incident light, the proposed method enables to produce a flattop filter with neither polarization-dependence nor reduction of the rejection depth.

© 2018 The Author(s)