High-power ultraviolet 278-nm laser from fourth-harmonic generation of an Nd:YAG amplifier in CsB<sub>3</sub>O<sub>5</sub> crystal

He Miao^{1, 2, 3}, Yang Feng^{1, 2, †}, Dong Cheng^{1, 2, 3}, Wang Zhi-Chao^{1, 2}, Yuan Lei^{1, 2}, Xu Yi-Ting^{1, ‡}, Zhang Guo-Chun², Wang Zhi-Min^{1, 2}, Bo Yong^{1, 2}, Peng Qin-Jun^{1, 2}, Cui Da-Fu¹, Wu Yi-Cheng², Xu Zu-Yan^{1, 2}