Narrow-linewidth injection-locked Ho:YAG laser by using thulium-doped fiber laser as pumping source

We demonstrated a narrow-linewidth Ho:yttrium aluminum garnet (YAG) injection-locked laser by using a 1908 nm thulium-doped fiber laser as a pumping source to generate 2.09 mu m single-frequency pulses. A compact single-longitudinal-mode nonplanar ring oscillator (NPRO) based on Ho:YAG material with a beam quality factor of 1.01 at the central wavelength of 2090.91 nm was considered as the seed source. In the experiment, the pulse energy of 3.6 mJ with a pulse width of 161.6 ns from single-frequency Ho laser was achieved at a pulse repetition frequency (PRF) of 100 Hz. The linewidth of the single-frequency pulse spectrum monitored through the heterodyne method was approximately 1.9 MHz at the lowest Ho laser energy.