Single-Longitudinal-Mode Fiber Ring Laser Stabilized by Tandem All-Fiber Fabry–Pérot Micro-Cavities

We demonstrate a stabilized single-longitudinal-mode fiber ring laser using tandem-Fabry-Pérot-microcavities (T-FP-MCs) as the all-fiber intracavity filter. The T-FP-MCs are formed with short adjustable air gaps between pairs of vertical cleaved single-mode fiber ends without mirror-coating deposition. The T-FP-MCs' spectral filtering effect is analyzed with the Rouard's method. Mode-hopping-free continuous-wave operation with 19-dBm power, 0.06-nm bandwidth and sidemode suppression ratio of 28 dB at 1565-nm wavelength is achieved using two T-FP-MCs. Q-switching pulsed operation of this fiber laser with 10-W peak power is also investigated and analyzed.