Coherent 420 nm laser beam generated by four-wave mixing in Rb vapor with a single continuous-wave laser

Liu Hao^{1, 2}, Yuan Jin-Peng^{1, 2, †}, Wang Li-Rong^{1, 2, ‡}, Xiao Lian-Tuan^{1, 2}, Jia Suo-Tang^{1, 2}

The measured beam quality M² of the output CBL. The black squares and the red dots are the experimental data for the x axis and y axis, respectively. The insert is the beam profile of the CBL.