2022/9/28 9:42:11 SUN Longquan, REN Zeyu, LI Zhipeng, MA Guihui, ZHAO Jianzhou 6true 2022/9/28 9:42:11 WU Wei, YU Naihui, LUO Zirong, BAI Xiangjuan, SHANG Jianzhong 5true 4Se₇ (BGSe) and the mature commercial nonlinear crystal KTiOAsO4 (KTA), the 1.06 μm laser was used to pump BGSe (56.3 °, 0 °, type-Ⅰ) and KTA (90 °, 0 °, type-Ⅱ-A) to output 3.5 μm laser. The pump oscillation threshold of KTA and BGSe was 52.6 mJ (the theoretical value was 46.11 mJ) and 20.6 mJ (the theoretical value was 18.32 mJ) respectively when the pump wavelength was 1 064 nm, the pulse width was 13 ns, the beam diameter was 4 mm and theoptical parametric oscillator, cavity length was 90 mm. The Δλ₂/ΔT of BGSe and KTA was 3.20 nm/℃(the theoretical value was 2.49 nm/℃) and 0.073 nm/℃(the theoretical value was 0.077 nm/℃). The output linewidth of BGSe and KTA was 4.71 nm and 2.45 nm respectively. The experimental results of the pump oscillation threshold and the temperature tuning range fit the theoretical simulation well, and the results show that BGSe is better than KTA in these two aspects. But the output linewidth of KTA is narrower than that of BGSe. The experimental results indicated that BGSe is a mid-to far-infrared nonlinear crystal with wide applications.]]> 2022/9/28 9:42:11 KONG Hui, BIAN Jintian, YE Qing, XU Haiping, SUN Xiaoquan 4true 2022/9/28 9:42:11 ZHAN Ronghui, WANG Liping 3true 2022/9/28 0:00:00 CHANG Junsheng, XIONG Zeyu, XU Jinbo 2true 2022/9/28 9:42:11 LI Xiankai, ZHANG Zhiyu, HE Miaosheng, ZHU Binbin, LIU Jun 1true