Tunable short-wave near-infrared continuous wave source based on a 532 nm pumped singly resonant optical parametric idler oscillator

Abstract

We report a continuous wave (CW) singly resonant optical parametric idler oscillator (i-SRO) capable of providing high power, high power conversion efficiency, widely tunable radiation in the short-wave near-infrared (NIR) range. The i-SRO is pumped by a fiber-laser-based laser at 532 nm with a multi-grating, MgO doped periodically poled stoichiometric lithium tantalate (MgO:sPPLT) as quasi-phase matching (QPM) crystal. By utilizing eight grating periods, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, and 8.8 µm of the QPM crystal, with grating tuning and temperature tuning, the i-SRO can be continuously tuned across 951–793 nm and the corresponding idler tunable over 1212–1620 nm. A maximum signal power of 4.9 W for a pump power of 9.1 W and a relevant pump to signal conversion efficiency of ∼53.8% are achieved at the signal of 821 nm. At a pump power of 5.4 W, the output power stability of the signal at 837 nm is better than 2.1% rms, within one hour in Gaussian spatial beam profile. The SRO performance in tuning rate has also been investigated.