1 kHz single-frequency 209 μm Ho:YAG ring laser

In this paper, we report the experimental realization of a high-repetition-rate single-frequency Ho-doped yttrium aluminum garnet (Ho:YAG) ring laser at 2.09 μm. Single-frequency operation of the ring laser is achieved by injection-seeding with a continuous wave (CW) Ho:YAG non-planar ring oscillator (NPRO) laser. The output energy of the ring laser is 6.24 mJ with a pulse width of 172 ns and a repetition rate of 1 kHz. The beam quality M2-factor is measured to be ∼1.3 at the maximum output energy. The half-width of the pulse spectrum is measured to be 2.61 MHz by a heterodyne technique.