Ultrafast 550-W average-power thin-disk laser oscillator

We present a SESAM modelocked ultrafast thin-disk laser oscillator providing 550 W of average output power with 852 fs pulses at 5.5 MHz repetition rate. To the best of our knowledge, this represents the highest average output power ever achieved from a modelocked oscillator. To reach this significant power scaling, a new replicating cavity design for modelocked oscillators is utilized. The oscillator delivers 103 MW of peak power with a pulse energy of 100 µJ at a beam quality of M²< 1.2, with a high optical-to-optical efficiency of 35%. As well as providing record average output power, this oscillator thus also provides, to the best of our knowledge, the highest pulse energy from any modelocked oscillator and the highest peak power from any SESAM modelocked oscillator. Advances in SESAM design and manufacturing that enabled this result are discussed, as well as practical challenges when scaling oscillators to the kW-class.