MULTIPLE-QUANTUM-WELL HETEROSTRUCTURES SHOWING OPTICAL NONLINEARITIESAT LOW-INTENSITY AND FAST RECOVERY

This paper focuses on photogenerated carrier nonlinearities in InGaAs/ InAlAs quantum wells (QWs) that use low optical power, display a relat ively fast recovery time (280 ps down to 35 ps), and excellent optical properties in terms of the sharpness of the absorption edge. A guided -wave, all-optical switching device is demonstrated as an application, at a wavelength which is of interest to telecommunication systems (1. 55 mu m) and requires low control energy (< 0.3 pJ/pulse). A key issue here is that the controlled introduction of defects in the QW heteros tructures allows the time response to be fastened significantly withou t being detrimental to the performance of the device in terms of on-of f contrast and switching energy. The preparation procedure is compatib le with metalorganic-based growth techniques widespread in optoelectro nics at 1.55 mu m.