Wavelength-Tunable All-PM All-Fiber Femtosecond Laser Based on Intracavity Loss Tuning

We reported a C+L-band wavelength-tunable femtosecond Er-doped fiber laser with the all-polarization-maintaining (all-PM) all-fiber structure. The figure-9 laser is stably mode-locked by combining phase-biased nonlinear amplifying loop mirror and a home-made PM-fiber end-face dielectric mirror. Continuous tuning of the mode-locking wavelength from 1559.09 to 1602.46 nm is achieved, which is attributed to the 1500-1650 nm broadband reflection of the PM-fiber end-face dielectric mirror and the intracavity loss control using a variable optical attenuator. The laser delivers femtosecond pulses with a minimum pulse duration of 331 fs and a maximum 3-dB spectral bandwidth of 10.38 nm. To the best of our knowledge, this is the widest wavelength tuning range achieved in strictly all-PM all-fiber Er-doped fiber lasers.