High-energy nanosecond pulse extraction from a Tm<sup>3+</sup>-doped photonic crystal fiber laser emitting at 2050 nm with narrow linewidth
Julian Schneider, Hugo Lassiette, Dominik Lorenz, Patrick Forster, Jan Lautenschläger, Dieter Panitzek, Clément Romano, Marc Eichhorn, Christelle Kieleck
Abstract
A nanosecond-pulsed diode-pumped Tm 3+ -doped fiber laser (TDFL) operating at 2050 nm is reported based on a flexible photonic crystal fiber (PCF) with a core diameter of 50 µm. Analytical evaluation of reabsorption effects and optimization of the fiber length allow enhanced pulse energy extraction at long wavelengths. This enables the generation of Gaussian-shaped pulses with pulse energies of 1.9 mJ, pulse widths of 116 ns, and peak powers of 15.4 kW from the TDFL. 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. With a slope efficiency of 44 %, the average output power of the pulsed TDFL is scaled up to 114 W. To the best of our knowledge, this represents the first demonstration of a Tm 3+ -doped PCF at a long emission wavelength of 2050 nm and the highest pulse energies from a TDFL based on a flexible fiber.