Spacing-adjustable and wavelength-tunable multiwavelength fibre laser with nonlinear Brillouin gain and birefringence fibre loop mirror

This paper demonstrates a room-temperature multiwavelengthfibre laser with spacing-adjustability and wavelength-tunability.The nonlinear gain of self-excited stimulated Brillouin scatteringcan suppress mode competition induced by homogeneous broadening ofErbium-doped fibre. With the use of a birefringence fibre loopfilter, the wavelength spacing can be adjusted by changing thelength of the used birefringence fibre, and the lasing wavelengthscan be finely tuned through modifying the filtering profile of thebirefringence filter. Multiwavelength output with spectral spacingas small as 0.076~nm and a wavelength number of more than 80 has beensuccessfully produced.