Novel semiconductor materials and saturable absorber mirrors for sub-10-fs pulse generation

摘要

We report on the fabrication of novel ultrabroadband AlGaAs/CaF₂ semiconductor saturable absorber mirrors (SESAMs) for sub-10-fs pulse generation. AlGaAs/CaF₂ Bragg mirrors provide high reflection bandwidths covering the whole gain spectrum of Ti:sapphire lasers. GaAs layers epitaxially grown on CaF₂ win be shown to be an excellent choice for the operation as saturable absorber with high modulation depth and fast recovery times. A monolithical SESAM device consisting of AlGaAs/CaF₂ Bragg mirror and GaAs saturable absorber started and supported successfully mode-locking in a Ti:sapphire laser. Sub-10-fs pulses have been generated. A broad pulse spectrum with a transform limit of 5.9 fs shows the potential of AlGaAs/CaF₂ for sub-6-fs pulse generation.