CW Mode-Locked 1.908 mu m Tm:LiYF4 Slab Laser Based on an Output-Coupling Graphene Saturable Absorber Mirror

We report a passively continuous wave (CW) mode-locked femtosecond 1.908 mu m Tm:LiYF4 (Tm:YLF) slab laser based on an output-coupling graphene saturable absorber mirror (GSAM) with a transmittance of 2.29%. Using an atmospheric-pressure chemical vapor deposition (APCVD) method with a C2H2 carbon source, triple-layer graphene was fabricated and transferred to an output-coupling mirror of 1.9 mu m wavelength range. Stable CW mode-locked laser pulses as short as 473 fs were measured with a repetition rate of 70.2 MHz and an average output power of 146.5 mW at 1.908 mu m. (C) 2013 The Japan Society of Applied Physics