Advances in 2 µm polarization-maintaining thulium-doped Q-switched fiber lasers for frequency conversion into the mid-IR

A diode-pumped actively Q-switched Tm3+-doped fiber laser is reported generating pulse energies of 800 μJ, pulse widths of 43 ns and peak powers of 17.5 kW. By using the single-oscillator as a pump source for nonlinear frequency conversion, mid-IR pulse energies of 230 μJ are extracted from a ZnGeP2 (ZGP) optical parametric oscillator (OPO).