Narrow-Linewidth 100-W-Level Microsecond TEM00Nd:YAG Twisted-Mode Laser

We demonstrated a compact high-efficiency 100-W-level, narrow-linewidth, quasi-continuous-wave (QCW) diode-side-pumped Nd:YAG laser with a linearly polarized TEM00 mode. Spatial hole-burning elimination and narrow-linewidth laser output were realized by a twisted-mode cavity and an etalon, respectively. The resonator was based on a thermally near-unstable cavity design with dual-rod birefringence compensation convex–convex structure. A 100.4-W linear polarized 1064-nm laser was achieved with a 340-W pump power, corresponding to an optical-to-optical conversion efficiency of 29.5%. The wavelength of the laser was tunable from 1064.22634 to 1064.68071 nm while stably maintaining a beam quality of M2 = 1.22 and a linewidth of ~240 MHz. The laser was operated at a repetition rate of 500 Hz with 160- $\mu \text{s}$ pulse duration. To the best of our knowledge, this represents the highest average-power and the highest brightness for narrow-linewidth QCW microsecond pulse 1064-nm lasers.