Semiconductor saturable absorbers of laser radiation for the wavelength of 808 nm grown by MBE: Choice of growth conditions

We investigate selected problems of the molecular beam epitaxy (MBE) technology of fabrication of semiconductor saturable absorbers, which are the main parts of broadband saturable absorber mirrors. These mirrors are designed for mode locking of solid-state lasers emitting in 808 nm band. We analyzed growth conditions during the MBE processes of fabrication of test structures containing the central part of the device with a quantum well (QW). Two main parameters were changed in the processes: the growth temperature of InGaAs/GaAs QW and the arsenic to metals flux ratio. Four types of growth conditions were applied during the test processes. Grown structures were tested by optical methods: photoreflectance and pump-probe spectroscopy (pump-probe measurements and saturation measurements). Obtained results enabled us to establish a correspondence between applied growth conditions and main optical parameters of the absorbers.