Self-starting all-fiber PM Er: laser mode locked by a biased nonlinear amplifying loop mirror

A compact all-fiber polarization-maintaining Er:laser using a nonlinear amplifying loop mirror is reported. Fundamental single-pulse mode-locking operation can always self start, with a cavity round-trip decreased from~4.7 m to~1.7 m. When the pulse repetition rate is 121.0328 MHz, output pulse is measured to have a center wavelength/3-dB spectral bandwidth/radio frequency signal to noise ratio (SNR)/pulse width of 1571.65 nm/18.70 nm/80 dB/477 fs, respectively. Besides, three states including the exponential growth, damping state, and steady state are investigated through the build-up process both experimentally and numerically. Excellent stability of this compact Er:laser is further evaluated, demonstrating that it can be an easy-fabrication maintenance-free ultrafast candidate for the scientific area of this kind.