Large scale oxidation of AlAs layers for broadband saturable Bragg reflectors

Summary form only given. Describes oxidation of AlAs to Al/sub x/O/sub y/ for use as a broadband saturable Bragg reflector (SBR) where an Al/sub x/O/sub y//GaAs mirror with lateral dimensions >300 /spl mu/m is required. For the SBR structure described, the simulated bandwidth extends from 1200 nm to 1800 nm with greater than 99.5% reflectivity. The layers within the SBR are grown using gas-source molecular beam epitaxy. The SBR structure contains an 8 period GaAs/AlAs quarter-wave stack grown on a GaAs substrate. The Al/sub x/O/sub y/ layer is initially grown as AlAs and later oxidized. The AlAs layer is relatively thick (240 nm) to correspond to a quarter wavelength in Al/sub x/O/sub y/ (n = 1.66) minus a 10% shrinkage upon oxidation. The active region consists of an InP/InGaAs quantum well emitting near /spl lambda/ = 1550 nm. The effects of the SBR for self-starting the laser cavity are detailed.