Widely Tunable C $+$ L Bands Multiwavelength BEFL With Double-Brillouin Frequency Shifts

A wideband multiwavelength Brillouin–erbium fiber laser (BEFL) with double Brillouin frequency spacing is demonstrated. The fiber laser structure utilizes a tunable band-pass filter and a pre-amplified Brillouin pump technique within a ring cavity. An average of six Brillouin–Stokes signals in C $+$ L bands with a constant wavelength spacing of 0.174 nm can be turned over a span of 80 nm from 1530 nm to 1610 nm. Total average output power of 8.5 mW from this laser structure was achieved. All the generated Brillouin–Stokes signals exhibit good stability, and high peak power of above $-$ 10 dBm per signal was demonstrated.