Integrated ultrafast saturable absorber

An ultrafast saturable absorber was demonstrated experimentally in AlGaAs, operated with a photon energy below half the band gap, near 1555 nm. Both the saturation intensity and the linear transmission can be independently designed in the structure. The device is based on spatial soliton emission from a tapered channel waveguide with a corresponding increase in transmission of 50%. The experimental data compare favorably with numerically simulated results.