All-in-one fiber laser based on a liquid crystal transducer

We report a new method of generating continuous-wave (cw) radiation, Q-Switched as well as mode-locked laser pulses from a single linear fiber laser cavity. The three operating modes can be selected by the electric signal that is applied to an intracavity liquid crystal (LC) transducer cell. In addition, this is the first demonstration of using an LC modulator as an active mode-locking device in a fiber laser oscillator to date. In the proof-of-principle experiments presented here, the Q-Switched laser pulses with a duration of 1.3 $ {\mu }\text{s}$ , a maximum energy of 2.7 $ {\mu }\text{J}$ , and a peak power of 1.93 W were generated at low repetition rates ranging from 0.2 to 6 kHz. In mode-locked operation, pulse trains with repetition rates as high as 944.5 kHz and a shorter duration of 65 ns were achieved. Finally, a slight modification of the LC cell allows for a direct comparison between amplitude modulation (AM) and frequency modulation (FM) mode-locking.