Stutzki, F.F.StutzkiGaida, C.C.GaidaGebhardt, M.M.GebhardtJauregui, C.C.JaureguiLimpert, J.J.LimpertTünnermann, A.A.TünnermannPupeza, I.I.Pupeza2022-03-132022-03-132017https://publica.fraunhofer.de/handle/publica/39770110.1117/12.22526622-s2.0-85019446561Ultrashort-pulse laser systems are an enabling technology for numerous applications. The stability of such systems is especially crucial for frequency metrology and high precision spectroscopy. Thulium-based fiber lasers are an ideal starting point as a reliable and yet powerful source for the nonlinear conversion towards the mid-IR region. Recently, we have demonstrated that nonlinear self-compression in a fused silica solid-core fiber allows for few-cycle pulse duration with up to 24 MW peak power using a high-repetition rate thulium-based fiber laser system operating at around 2 mm wavelength [1]. This experiment operates near the self-focusing limit of about 24 MW for circular polarization, which increases the requirements for the system stability due to the risk of a fiber damage. Here, we present a self-protecting nonlinear compression regime allowing for long-term operation and high output-pulse stability with very similar output performance.en620conference paper