Deep-Infrared Picosecond Optical Parametric Oscillator Based on CdSiP2 Delivering 190 mW of Average Power at 6.2 μm

Ultrafast picosecond sources in the 6–7 μm deep-infrared (deep-IR) wavelength range are of interest for a variety of applications including spectroscopy, upconversion imaging, and precision surgery [1]. In the absence of conventional laser gain media, synchronously-pumped optical parametric oscillators (OPOs) based on cadmium silicon phosphide, CdSiP2 (CSP) offer an effective solution, delivering practical output power in this wavelength range. The unique properties of CSP crystal, including a high nonlinearity and compatibility with commercially available 1-μm laser pumping, make it an ideal material candidate for deep-IR generation. In this report, we present an efficient, high-repetition-rate picosecond OPO based on CSP pumped by an Yb-fiber laser, delivering the highest deep-IR average power achieved to date, as much as 190 mW at 6271 nm, together with 22 mW of signal power in the near-IR, at an overall conversion efficiency of 8.5%. The record performance is achieved by exploiting high peak pump power together with relaxed focusing condition to minimize thermal effects [2].