Femtosecond enhancement cavity with kilowatt average power

Zhang Jin^{1, 2}, Hua Lin-Qiang^{1, †}, Yu Shao-Gang^{1, 2}, Chen Zhong^{1, 2}, Liu Xiao-Jun^{1, ‡}

Theoretical beam radius at the focus as a function of concave mirror separation calculated by ABCD matrix method.