Tunable single-longitudinal-mode Er:YAG laser using a twisted-mode technique at 1.6 μm

We demonstrated a diode-pumped tunable single-longitudinal-mode Er:YAG laser using a twisted-mode technique at 1.6 μm. The maximum single-longitudinal-mode output power of 315 mW was obtained at 1645.3 nm, corresponding to a slope efficiency of 7.7%. The single-longitudinal-mode laser has a beam quality factor of M2 ~ 1.07. The output wavelength can be tuned from 1644.8 to 1646.1 nm by changing the etalon angle. In addition, by changing an output coupler, a maximum single-longitudinal-mode output power of 130 mW at 1617.2 nm with a slope efficiency of 3.3% was also achieved. The output wavelength can be tuned from 1616.9 to 1617.4 nm by changing the etalon angle. The twisted-mode Er:YAG laser operated at single-longitudinal mode is being reported for the first time to the best of our knowledge.