Wavelength-switchable erbium-doped fiber ring laser employing chirped Moiré fiber grating and tunable Sagnac loop interferometer filter

Abstract

A simple, cost-effective and switchable five-wavelength fiber ring laser based on a chirped moiré fiber grating (CMFG) and a wavelength-tunable Sagnac loop interferometer (FSI) filter is proposed and experimentally demonstrated. To serve as wavelength selective element, the CMFG possesses excellent comb-like filtering characteristics including stable wavelength interval and ultra-narrow passband, and its fabrication method is easy and flexible. The usage of the FSI filter helps remove the high-cost optical circulator and improve the output performance of optical signal-to-noise ratio from 50dB to 70dB. With this laser configuration, the output power fluctuation of each wavelength is less than 0.5 dB within a one-hour period, and the output power of different channels is almost identical (difference less than 1dB) within the tunable range.