High efficiency, single-frequency continuous wave Nd:YVO₄/YVO₄ ring laser

An efficient single-frequency laser-diode pumped, continuous wave (CW) ring Nd laser emitting at 1064.4 nm is demonstrated. A composite crystal (Nd:YVO₄/YVO₄) with un-doped ends is single end pumped by a fiber-coupled laser diode (LD) at 808 nm. A four-mirror ring cavity is deigned to keep the laser unidirectional operating, which eliminate spatial hole burning in standing-wave cavity. With the incident pump power of 31.5 W, the obtained output power is 13.6 W, with a slope efficiency of 52.6% and an optical efficiency of 43.2%. At the same time, a beam quality of M² ∼1.1 is found.