We demonstrate what is to our knowledge the first ultrabroadband monolithically grown AlGaAs/CaF<sub>2</sub> semiconductor saturable-absorber mirror (SESAM) that covers nearly the entire gain spectrum of a Ti:sapphire laser. A large high-reflectivity bandwidth of more than 300 nm is provided by a device consisting of only six material layers. This fluoride SESAM had a modulation depth of 2.2%, a fast recovery time constant of less than 150 fs, and a slow recovery time constant of 1.2 ps. Using this SESAM inside a Ti:sapphire laser produced self-starting sub-10-femtosecond pulses.
© 2002 Optical Society of America
(160.4330) Materials : Nonlinear optical materials
(310.3840) Thin films : Materials and process characterization
(320.7080) Ultrafast optics : Ultrafast devices
(320.7100) Ultrafast optics : Ultrafast measurements
S. Schön, M. Haiml, L. Gallmann, and U. Keller, "Fluoride semiconductor saturable-absorber mirror for ultrashort pulse generation," Opt. Lett. 27, 1845-1847 (2002)