High-pulse-energy Tm3+-doped photonic crystal fiber laser for nonlinear frequency conversion into the mid-IR

A nanosecond-pulsed Tm-doped fiber laser (TDFL) operating at 2050 nm is reported based on a flexible photonic crystal fiber with a core diameter of 50 μm. The TDFL delivers gaussian-shaped pulses with a maximum pulse energy of 1.9 mJ, corresponding to a peak power of 15.4 kW and a pulse width of 116 ns. The average output power of the pulsed TDFL is 114 W at a pulse repetition rate of 60 kHz. The measured output spectrum shows a single peak at 2050 nm with a 3-dB-linewidth of 130 pm and a 10-dB-linewidth of 370 pm. The TDFL serves as an excellent pump source for mid-IR generation through nonlinear-frequency conversion in optical parametric oscillators based on ZnGeP2.