High brightness diode pumped Er:YAG laser system at 2.94 μm with nearly 1 kW peak power

We demonstrated a monolithic high-power diode-pumped Er:YAG laser at 2.94 mu m with average output power of up to 50 W and pulse energy beyond 300 mJ in 400 ps pulses. The high peak power of nearly 1 kW is delivered in a high quality beam (M-2 < 15), maintained over a large cooling water temperature range of 18-25 degrees C. The improved resonator configuration allows for stable operation from 0-10 % duty-cycle in contrast to prior developments showing saturation. As a first application, fiber-coupling into a 230 mu m, 0.2 NA GeO2-fiber with standard optics has been shown, reaching 30W average power and 200 mJ pulse energy out of the fiber, only limited by the fiber.