Widely tunable (2.6–10.4μm) BaGa₄Se₇optical parametric oscillator pumped by a Q-switched Nd:YLiF₄laser

Abstract

We report on the first BaGa 4 Se 7 nanosecond optical parametric oscillator pumped by Q-switched Nd:YLiF 4 laser at 1053 nm. The oscillator exhibits a pump threshold energy as low as 0.25 mJ. Midinfrared (MIR) idler wave tuning from 2.6 μm to 10.4 μm is demonstrated with an angle-tuned type-I (o-ee) y-cut sample, highlighting the superior performance of this novel large bandgap chalcogenide nonlinear crystal to generate tunable coherent radiation over its full MIR transparency range (0.47-18 μm). The phase-matching data are used to identify the most accurate dispersion relations of this compound among three recently published Sellmeier equations. Damage threshold measurements yielded values as high as 2.04 J cm −2 at 100 Hz pulse repetition rate, one of the largest among existing MIR χ (2) nonlinear materials.

Narrow-linewidth BaGa4Se7 optical parametric oscillator

“…In 2016, Kostyukova et al [8] used a 1064 nm Nd:Y 3 Al 5 O 12 (Nd:YAG) laser to pump the BGSe OPO, and an ultra-broad tunable range of 2.7-17 μm was obtained, with a maximum pulse energy of 3.7 mJ at 7.2 μm. In 2018, Kolker et al [9] reported on the first, to the best of our knowledge, BGSe nanosecond OPO pumped by a Q-switched Nd:YLiF 4 laser at 1053 nm, and an ultra-broad tunable range of 2.6-10.4 μm was obtained. In 2018, Zhao et al [10] demonstrated a tunable 8-9 μm OPO with a type II phase-matching BGSe pumped by a 2090.7 nm acousto-optical Q-switched Ho:YAG laser, and a spectral bandwidth of 67.8 nm at 8925.7 nm was achieved.…”

High Pulse Energy, Narrow Linewidth 6.45 μm from an Optical Parametric Oscillator in BaGa4Se7 Crystal

“…Several works on 6.45 µm ns MIR generation, from a 1 µm laser based on BGSe-OPO, were reported [19,20]. For example, a ns BGSe-OPO pumped by Q-switched Nd:YLiF 4 laser at 1053 nm was reported.…”

Intracavity-Pumped, Mid-Infrared Tandem Optical Parametric Oscillator Based on BaGa4Se7 Crystal

“…Recently, the newly developed BGSe crystal with high performances is considered as a very promising NLO crystal for widely tunable and high-energy mid-infrared wave generation, especially pumped at 1 μm [12]- [16]. BGSe crystals with long length (14.5-30 mm) have been employed in the widely tunable and high-energy mid-infrared OPO sources, which were pumped by different fixed wavelengths of 1.053 μm, 1.064 μm, 2.1 μm and 2.79 μm under type I and type II phase-matching (PM) conditions [17]- [22] with angle-tuning method. Except for the angle-tuning method, many tuning methods have been employed in the OPO sources instead of tilting the angle of crystals, including temperature-tuning and pump-tuning methods.…”