Photon counting 1060-nm hybrid photomultiplier with high quantum efficiency

An ultra-low-noise, high-speed, hybrid photomultiplier tube sensitive from 900 to 1300 nm optical wavelengths is described. The device, also known as an intensified photodiode (IPD), uses an active transferred electron (TE) p hotocathode with the quaternary In.69Ga.31As.67P.33 photo-absorbing layer a nd a GaAs Schottky avalanche photodiode (SAPD) anode. The detector has a co mbined electron bombarded and avalanche gain of over 15 000 which is suffic ient to overcome preamplifier noise and provide high internal counting effi ciency of approximately 85%, At an active cathode bias of 1.5 V the room te mperature cathode dark countw rate is 6.67 x 10(5)/s, Cooling reduces this substantially corresponding to a dark current activation energy almost equa l to the bandgap of the In.69Ga.31As.67P.33 layer.