Single-frequency, all-fiber Q-switched laser at 1550 nm

We present a novel actively Q-switched single frequency, linear, all-fiber laser using fast stress-induced birefringence modulation. We demonstrate 25-W peak power in 12-ns, 0.3-µJ pulses at a repetition rate of 80 kHz with 370 mW of pump power, without using an amplifier. Very effective Q-switching was also observed at 325 kHz, near the resonance frequency of the piezoelectric actuator. Using a higher pump power of 780 mW, an average output power of 85 mW and pulsewidth of 16 ns at 325 kHz PRF was observed.