Microwave characterization of optically modulated photo-induced switches with a passivation layer using an LSNA

A measurement set-up has been developed to characterize the electrical response to a pulsed optical excitation on photo-induced switches. The hardware configuration is a combination of a 50 GHz LSNA and a laser modulated by a pulse generator. By making use of vector large-signal measurements, the pulse envelope response is measured which allows the study of transient effects as well as the determination of performance parameters such as excess carrier lifetime. It is demonstrated that depositing a passivation layer beneath the CPW transmission line switch reduces the carrier life time considerably.