Wide tuning range and high OSNR self-seeded multi-wavelength Brillouin-erbium fiber laser based on a Lyot filter

A tunable self-seeded multi-wavelength Brillouin-erbium fiber laser (BEFL) based on a Lyot filter is experimentally demonstrated in this paper. The Lyot filter is constructed by a polarization-dependent isolator (PDI), two polarization controllers (PCs), and a 20-cm-length polarization-maintaining fiber. In this proposed structure, the PDI is used as a polarizer. Due to the periodic filtering characteristics of the Lyot filter, the multi-wavelength output of the laser shows different Brillouin bands by adjusting the PCs. In the experiment, a single Brillouin band can be produced with the tuning range of 30 nm, from 1527.8 to 1557.8 nm. The optical signal-to-noise ratio (OSNR) of the output wavelengths is ∼20 dB. Dual Brillouin bands are observed.