GaN-based semiconductor saturable absorber mirror operating around 415 nm

We report a broadband GaN-based semiconductor saturable absorber mirror (SESAM) operating around 415 nm. The GaInN quantum wells (QWs) acting as saturable absorbers were grown by metal-organic chemical vapor deposition (MOCVD). A broadband dielectric high-reflective distributed Bragg reflector (DBR) was deposited onto the QW sample using plasma-enhanced chemical vapor deposition (PECVD) to build the SESAM. The SESAM has a stopband of over 100 nm. The linear and nonlinear transmission/absorption from QWs and the reflectance from DBR and SESAM were studied. This SESAM can be applied in passively mode-locking blue lasers such as GaN-based semiconductor lasers for producing ultra-short optical pulses