Direct generation of 3.5 optical-cycle pulses from rare-earth laser

• DOI: 10.1364/opticaopen.28455185.v1
• Publication Date: 2025-02-24T04:47:19Z
• Authors: Yongguang Zhao; Ning Zhang; Yinyin Wang; Heng Ding; Fei Liang; Jun Xu; Haohai Yu; Huaijin Zhang; Valentin Petrov

Unlike the conventional mode-locked laser where cooling system is normally used for gain medium, here, we propose a new strategy to originally extend modelocked bandwidth through increasing crystal temperature. Mode-locking of thulium-laser with superbroadband (> 600 nm) centered at 2.05-μm has been realized, corresponding pulse duration 26 fs (3.5 optical cycles), which represents shortest pulses ever achieved from Tm/Ho-lasers in 2-μm spectral range and fewest cycles all present-day RElasers. This work, as proof principle study, opens route towards direct generation extremely short pulses.