Fiber-bulk hybrid Er:YAG laser with single frequency output at the wavelengths of 1620 nm and 1656 nm

A fiber-bulk hybrid Er:YAG single frequency laser at the wavelengths of 1620 nm and 1656 nm is demonstrated. The laser is pumped by a 1532 nm Er,Yb fiber laser. Two intra-cavity etalons are utilized to realize the single frequency operation. The laser achieved up to 478 mW and 276 mW single-longitudinal-mode output at 1620 nm and 1656 nm, respectively. To the best of our knowledge, this is the first time a continuous single-longitudinal-mode laser output at 1620 nm and 1656 nm in a Er:YAG laser has been achieved.