Applicability of Graphene Flakes as Saturable Absorber for Bulk Laser Mode-Locking

We investigated the applicability of graphene flakes as a potential mode-locking device for bulk solid-state lasers. Graphene-flake-based saturable absorbers fabricated by a relatively simple process with commercially available graphene flakes exhibit suitable saturable absorption and ultrafast nonlinear optical response. We achieved stable 97-fs pulses from a mode-locked Cr:forsterite laser near 1.25 mu m, delivering an average output power of up to 137 mW at 75.4 MHz. This work proposes an efficient parameter-engineering method for the graphene-based absorbers and is the first to demonstrate the use of graphene flakes for a mode-locked femtosecond bulk solid-state laser. (C) 2013 The Japan Society of Applied Physics