Powerful and compact coherent radiation source with wavelength covering the 8–14 µm mid-Infrared spectral range is crucial for a number of applications. Here we present a compact high energy widely and continuously tunable picosecond (ps) coherent radiation source from an optical parametric amplifier (OPA) in BaGa₄Se₇ (BGSe) crystal, providing hundreds of microjoule energy across 8–14 μm. The BGSe-OPA was pumped by a ps 1064 nm laser at a pulse repetition rate of 10 Hz. With a maximum pump energy of 14 mJ, the idler energy of >140 µJ over the entire tuning range was achieved. The maximum idler energy was up to 230 µJ at 9.5 µm, corresponding to a pump to idler energy efficiency of 1.6% and a photon conversion efficiency of 14.7%. Moreover, the corresponding phase-matching angles for 8–14 μm generation were measured experimentally by optical parametric generation method. Finally, the nonlinear absorption of BGSe crystal under 1064 nm pumping was investigated for the first time. The conversion efficiency, typical pulse temporal shapes and beam spatial profiles of idler light generation were calculated based on a BGSe-OPA numerical model.

强大而紧凑的相干辐射源，其波长涵盖8–14 µm中红外光谱范围，对于许多应用而言至关重要。在这里，我们从BaGa ₄ Se _7中的光学参量放大器（OPA）展示了一种紧凑的高能量，广泛且连续可调的皮秒（ps）相干辐射源。（BGSe）晶体，可在8-14μm范围内提供数百微焦耳的能量。BGSe-OPA由ps 1064 nm激光以10 Hz的脉冲重复频率泵浦。在最大泵浦能量为14 mJ的情况下，在整个调谐范围内获得的惰轮能量> 140 µJ。最大的惰轮能量在9.5 µm时高达230 µJ，相当于泵到惰轮的能量效率为1.6％，光子转换效率为14.7％。此外，通过光学参量生成方法实验性地测量了用于生成8-14μm的相应相位匹配角。最后，首次研究了BGSe晶体在1064 nm泵浦下的非线性吸收。基于BGSe-OPA数值模型，计算了空转光产生的转换效率，典型脉冲时间形状和光束空间分布。