Within this project, we proposed to demonstrate optically and electrically pumped MIXSELs (OP-MIXSELs and EP-MIXSELs) in both the pico- and femtosecond regime. Picosecond MIXSELs are ideally suited for clocking applications whereas femtosecond MIXSELs are required for continuum generation and many biomedical applications. For both cases average powers of >100 mW with electrical pumping and >500 mW with optically pumping need to be demonstrated. Saturable absorbers need to be optimized for integration into a MIXSEL and further developed for femtosecond pulse generation. We will mostly rely on quantum dot saturable absorbers and will explore the different trade-offs of quantum well versus quantum dot gain sections. We will perform a systematic design optimization of MIXSELs backed by numerical simulations. A drift-diffusion model can be used for the carrier transport and a transfer matrix method for optical simulation. These models will be extended with electro-optical and electro-opto-thermal simulations. Supercontinuum generation will be initially investigated with femtosecond diode-pumped solid-state lasers and then compared to the newly developed femtosecond MIXSELs.
We overachieved many of our target goals by far with high power ps OP-MIXSEL, 1 W fs OP-VECSEL and recently with the first fs OP-MIXSEL. Electrical pumping is still very challenging, more than initially anticipated, but we significantly improved our design leading to record short pulses from this type of modelocked lasers.