High-energy single-longitudinal-mode mid-infrared optical parametric amplifier seeded with sheet optical parametric oscillator

Mid-infrared (MIR) radiation is essential for remote gas sensing, ranging, and lidar applications, where high pulse energy and narrow linewidth are the keys to the high sensitivity over long distance. However, complex optical and electronic locking schemes are normally required to achieve both features at the same time. Here, we demonstrate pulse-pumped single-longitudinal-mode (SLM) MIR generation using a microresonator seed in the form of a sheet optical parametric oscillator (SOPO). The SOPO features a sub-coherence-length thickness of 400 µm, which enables SLM and high-energy oscillation using cavity phase matching. Its output around 1.55 µm is seeded into an optical parametric amplifier and locks the MIR output in SLM at 3.38 µm. In a simple and compact setup, up to 21% conversion efficiency and 22% slope efficiency are measured with a MIR output energy of 54 µJ. This SLM MIR source with the SOPO seed greatly reduces the system size and is compatible for further integration for field-deployable devices and thus has broad applications in the field of remote gas sensing.