High-peak-power operation of a Q-switched Tm^3+-doped silica fiber laser operating near 2 µm

A peak output power of greater than 4.1 kW and a pulse duration at FWHM of 150 ns have been obtained in a $Q$-switched ${\mathrm{Tm}}^{3+}$-doped silica fiber laser in the wavelength region near $2 \mathit{\mu }\mathrm{m}$ when the laser was pumped with a Nd:YAG laser operating at $1.319 \mathit{\mu }\mathrm{m}$. An acousto-optic modulator was used as a $Q$-switching element and operated at repetition rates of as much as 30 kHz. A core diameter of $17 \mathit{\mu }\mathrm{m}$ was used to increase the laser gain volume, permitting high-pump-power absorption and an output of high pulse energy and peak power. Stimulated Brillouin scattering was directly observed in the output pulse, and as much as 10 orders of stimulated Brillouin scattering was recorded. This is the first report to the authors’ knowledge of high-peak-power operation of a ${\mathrm{Tm}}^{3+}$-fiber laser.