SINGLE-PHOTON AVALANCHE-DIODE WITH ULTRAFAST PULSE RESPONSE FREE FROMSLOW TAILS

A single-photon avalanche diode (SPAD) with a novel structure is prese nted here. The slow tail in the pulse response, which plagued the perf ormance of previous ultrahigh-speed SPAD's, has been eliminated. The p ulse response is cleaner and sharper than that of the fastest microcha nnel-plate photomultipliers (MCP's), making the new devices almost ide al for photon timing measurements of fast optical waveforms. The typic al photon detection efficiencies are 16% at 630 nm and 4% at 850 nm an d the timing resolution of the 8-mum devices is 45-ps full width at ha lf maximum (FWHM). Unprecedented performance is demonstrated: just 300 ps after a light pulse, a signal three order of magnitude weaker can be easily measured.