S-band single longitudinal mode erbium-doped fiber laser with narrow linewidth based on passive multiple-subring resonator

Abstract

A stable S-band single longitudinal mode (SLM) erbium-doped fiber laser (EDFL) with narrow linewidth based on passive multiple-subring resonator (PMSR) has been proposed and experimentally verified. The designed structure of PMSR can effectively expand the equivalent free spectral range and eliminate dense longitudinal modes. In addition, the dual-coupled fiber ring contained therein can form a narrow-band comb filter with good mode selection performance. Incorporating a section of saturable absorber can effectively suppress mode hopping and maintain stable SLM laser oscillation. The proposed S-band EDFL demonstrates that the linewidth is as narrow as 763.427 Hz. An optical signal-to-noise ratio of about 70 dB centered at 1499.770 nm and a wavelength stability of 0.04 nm have been obtained, respectively. This S-band EDFL is promising for the future S-band applications.