Compact actively Q-switched laser for sensing applications

Current active Q-switching is mainly generated by acousto-optical modulators (AOMs) or electro-optical modulators (EOMs). However, EOMs make the setup bulky, while AOMs require the radiofrequency (RF) signal and water-cooling. We present a novel approach to active Q-switching of an integrated waveguide chip laser by utilizing a deformed helix ferroelectric liquid crystal cell (6mm×6mm) with a thickness of 2 mm. This device can be directly integrated onto the Ytterbium-doped waveguide chip and controlled by the electrical signal. In experiments, with an electrical signal with a pulse duration of 2 μs and a magnitude from 10 V to 84 V, the Q-switched lasers can be observed at a repetition rate ranging from 0.1 kHz to 20 kHz. The shortest pulse duration and the maximum slope efficiency is 38 ns and 22% respectively. This novel integrated and low-cost laser source is a promising tool for a broad range of applications such as gas sensing and LIDAR.