Q-switched all-fiber laser with an acoustically modulated fiber attenuator

An actively Q-switched all-fiber laser based on an acoustically modulated fiber attenuator was implemented for producing 1550.5 nm pulses of 3 μJ in pulse energy, 150 ns in pulse width, and 5 kHz in pulse repetition frequency. The fiber attenuator was combined with a fiber Bragg grating, which was used as the end mirror and the wavelength selector of the laser system. The fiber attenuator was implemented with the excitation of transverse vibration by a modulated acoustic wave. The transverse vibration or micro bending led to the coupling of the core mode and cladding modes. Through this mechanism, the feedback level from the fiber grating or the Q factor of the laser can be well controlled. The Q-switched fiber laser based on this scheme can be quite simple.