Silicon photonics-based high-energy passively Q-switched laser

Abstract

Chip-scale, high-energy optical pulse generation is becoming increasingly important as integrated optics expands into space and medical applications where miniaturization is needed. Q-switching of the laser cavity was historically the first technique to generate high-energy pulses, and typically such systems are in the realm of large bench-top solid-state lasers and fibre lasers, especially in the long wavelength range >1.8 µm, thanks to their large energy storage capacity. However, in integrated photonics, the very property of tight mode confinement that enables a small form factor becomes an impediment to high-energy applications owing to small optical mode cross-sections. Here we demonstrate a high-energy silicon photonics-based passively Q-switched laser with a compact footprint using a rare-earth gain-based large-mode-area waveguide. We demonstrate high on-chip output pulse energies of >150 nJ and 250 ns pulse duration in a single transverse fundamental mode in the retina-safe spectral region (1.9 µm), with a slope efficiency of ~40% in a footprint of ~9 mm2. The high-energy pulse generation demonstrated in this work is comparable to or in many cases exceeds that of Q-switched fibre lasers. This bodes well for field applications in medicine and space.

GeS2 Nanosheets as Saturable Absorbers for High Signal-to-Noise Ratio in an L-Band Ultrafast Pulsed Laser

“…Ultrafast pulsed fiber lasers have achieved great development for their potential applications in enormous fields such as photodetection, material processing, medicine, and sensors. − For various ultrafast laser devices, the signal-to-noise ratio (SNR) is a crucial index, which determines the success or failure of many physical experiments, especially those related to solid targets . Fiber mode-locked lasers with high SNR performance are expected to replace solid-state lasers as the next-generation seed source in future high-power laser systems .…”