1.9 picosecond optical temporal analyzer using 1.2 picosecondphotodetector and gate

摘要

The authors report on a novel photoconductive-type detector with aresponse time of 1.2 ps. This is the fastest photodetector to date. Itis based on low-temperature-grown GaAs and uses interdigitatedelectrodes of 0.2 μm spacing to match the carrier transit time to thecarrier lifetime. The responsivity is 0.1 A/W. The detector can bedriven to an on-state resistance of a few of ohms, with the responsetime increasing to only 1.5 ps. The photodetector can therefore alsofunction as a picosecond photogate. The two components have beencombined to form an all-semiconductor optical temporal analyzer. Thesystem response time is 1.9 ps, with a minimum detectable average powerof 500 pW. The technique is jitter-free, permitting long integrationtimes. Ultraweak picosecond fluorescence and scattering experiments, aswell as other ultrafast phenomena can be time-resolved using thisrelatively simple tool