Tunable C + L bands triple frequency spacing multi-wavelength Brillouin-erbium fiber laser

•A widely tunable C + L bands triple frequency spacing multiwavelength Brillouin-erbium fiber laser is presented.•A tuning range of 60 nm from 1535 nm to 1595 nm is achieved.•The laser structure does not require filtering techniques to tune the output channels and eliminate laser cavity modes.•Output channels exhibit good flatness and stability with minimal power fluctuation. We propose and experimentally demonstrate a wide tuning range triple frequency spacing multi-wavelength Brillouin erbium fibre laser (MBEFL). The laser can be tuned in the C- and L-bands of the optical communication windows. At a Brillouin pump power of 3 dBm and 1480-nm pump power of 195 mW, the proposed MBEFL generates up to five triple spacing Brillouin Stokes lines that can be tuned over 60 nm (from 1535 to 1595 nm). A wide tuning range is achieved through the combined techniques of pre-amplification and a virtual mirror of stimulated Brillouin scattering in the laser cavity. The generated Brillouin Stokes lines exhibit good flatness and stability with minimal power fluctuation.