Highly efficient, broadly tunable 2-µm femtosecond Tm:KYW laser

摘要

Ultrashort-pulse lasers operating around the 2-µm spectral region are of great interest for applications in time-resolved spectroscopy, nonlinear frequency up-conversion to the mid/far-infrared spectral regions, mid-IR supercontinuum generation, optical communications and photomedicine. Tm³⁺ doped crystalline gain media represent an attractive option for development of high-power, broadly tunable diode-pumped lasers around 2 µm that can be readily configured for ultrashort pulse generation through appropriate mode locking schemes. The best results in terms of pulse duration have to date been obtained with a Tm:KLu(WO4)2 laser [1] that produced 10-ps pulses at 1944 nm and a Tm:GdLiF4 laser that generated ∼ 17–44 ps pulses tuned from 1868 nm to 1926 nm. [2] Here we report, for the first time to our knowledge, a femtosecond Tm³⁺:KY(WO4)2 (Tm:KYW) laser that operates in the 1985–2065 nm spectral range by incorporating a semiconductor saturable absorber mirror (SESAM)