Polycrystalline silicon films, deposited on fused silica substrates, have been implemented as fast-response-time photoconductive switches. The switches were illuminated with 800-nm, 100-fs optical pulses from a Ti:sapphire model-locked laser, and the photoresponse was observed using both a 34-GHz sampling osiclloscope and a subpicosecond electro-optic (EO) sampling system. We observed a 3-ps transient with the EO sampler, which is the fastest signal ever reported for this type of material. The switch also responded to 1.55-#mu#m femtosecond laser pulses with transient signals as short at 36 ps, limited by the switch geometry.
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