Switchable and tunable erbium-doped fiber laser with the embedded Lyot filter

In this paper, a switchable and tunable erbium-doped fiber laser (EDFL) using an embedded Lyot filter is tested. The embedded Lyot filter based on a polarization-maintaining fiber (PMF) is theoretically analyzed and experimentally verified. By adjusting three polarization controllers (PCs), the output wavelengths in different wavelength states are emitted. By adjusting PC1, the output wavelengths can be switched among the single-wavelength output state and four different multi-wavelength output states, which are dual-, triple-, quad- and quintuple-wavelength outputs. In addition, the side-mode suppression ratio (SMSR) in this study can be up to ~ 53 dB. By adjusting PC2 and PC3 simultaneously, the output wavelengths show good tunability, and when in triple or quad-wavelength state, the wavelength interval is tunable.