Pulse Delay Measurements in Cascaded Quantum-Well Gain and Absorber Media

A tunable delay of ultrashort laser pulses in semiconductor waveguide structures are demonstrated in cascaded amplifying and absorbing semiconductor waveguides and compared with a single sectioned waveguide. The single sectioned waveguide shows a low transmission at the maximum delay. This is effectively avoided with the cascaded waveguide configuration, where it is demonstrated viable achieving a net pulse delay while maintaining a transmission of unity. For both types of devices, a pulse advancement is observed, at large pulse energies, that existing models are unable to account for.