Antimonide semiconductor saturable absorber for passive mode locking of a 1.5-μm Er : Yb : glass laser at 10 GHz

We demonstrate the first antimonide (AlGaAsSb) semiconductor saturable absorber mirror (SESAM) for stable passive mode locking of an Er : Yb : glass laser at 10 GHz and a center wavelength of 1535 nm generating 4.7-ps pulses. The nearly resonant SESAM is InP-based, grown by metal-organic vapor phase epitaxy and optimized for high pulse repetition rates. We fully characterized the linear and nonlinear optical parameters: The saturation fluence is 80 μJ/cm
²
, the modulation depth is 0.4% and the nonsaturable losses are 0.35%. A 1/e decay time of 95 ps is achieved after wet chemical etching of the 10-nm InP cap on top of the absorber.