High SMSR and widely tunable multi-wavelength erbium doped fiber laser based on cascaded filters

In this paper, a widely tunable multi-wavelength erbium doped fiber laser (EDFL) with high side mode suppression ratio (SMSR) is proposed and experimentally demonstrated. With the cascaded structure of Sagnac loop filter (SLF) and a homemade twin core photonic crystal fiber (TCPCF), the proposed EDFL could achieve a wide tunable range without sacrificing the SMSR. By properly adjusting the polarization controller (PC) and the bending stage, switchable single-, dual-, and triple-wavelength lasing outputs can be obtained. The tuning range can reach up to 23 nm and the highest SMSR is 57 dB for single-wavelength lasing. Moreover, dual-wavelength lasing outputs with the tuning range of 19 nm and SMSR higher than 40 dB can also be obtained. The proposed widely tunable EDFL with high SMSR has great significance for many applications such as optical fiber communication, distributed fiber optic sensing and microwave generation.