All polarization maintaining single-longitudinal-mode Brillouin/Erbium fiber laser with ultra-narrow linewidth and high stability

A high-performance all polarization maintaining (PM) single-longitudinal-mode (SLM) ring cavity Brillouin/Erbium fiber laser with an ultra-narrow linewidth, an ultra-high OSNR and high stability is investigated and experimentally demonstrated. The all-PM structure design and a stable distributed feedback fiber laser as the Brillouin pump (BP) can improve the output stability of the Brillouin/Erbium fiber laser. A short commercial PM erbium-doped fiber (EDF) serving as both the Brillouin and the linear gain media, together with the ring cavity structure of the Brillouin/Erbium fiber laser, facilitates exciting stimulated Brillouin scattering in the EDF. At the BP power of 10 mW and at the pump power of 150 mW, we obtain an SLM Brillouin/Erbium fiber laser with a linewidth as narrow as 476 Hz and an optical signal-to-noise ratio as high as 76 dB. Meanwhile, during the observation of 40 min, the lasing wavelength stability of the proposed fiber laser is 0.004 nm.