A new kind of fast quantum-well semiconductor saturable-absorber mirror with low losses for ps pulse generation

We demonstrate a new type of monolithic fast semiconductor saturable-absorber mirror simple to manufacture. It consists of a Bragg mirror (R>99.7%) and a quantum-well, grown by MOCVD in one run under standard conditions, placed at 1-2 nm from an interface with fast surface recombinations to deep trapping levels. GaAs-based and InP-based SESAM structures have been grown for the 0.98 μm and 1.55 μm spectral range respectively. We obtained as short as 21 ps excited carrier lifetime in the well, and a device with ∼0.5% saturable losses and negligible nonsaturable losses, as well as a group-delay-dispersion in the range +/-200 fs² over >20THz, a saturation fluence ∼100×10^-6 J/cm². This low cost SESAM is well suited for sub-ps passively modelocked laser system, as well as for all-optical regeneration devices for telecom applications by adapting the design.