Single-photon counting at 950–1300 nm: using InGaAsP photocathode–GaAs avalanche diode hybrid photomultiplier tubes

Abstract

We describe the single-photon counting performance of a hybrid photomultiplier tube (HPMT) near-infrared (950–1300 nm) detector with a transfered electron InGaAsP photocathode and a GaAs Schottky avalanche diode anode. These devices have a lower photoelectron multiplication gain than conventional photomultiplier tubes, but offer a greater linear dynamic range and electrical bandwidth. With the use of a low-noise preamplifier, they can detect single photons with a greater than 20% quantum efficiency (QE) and a reasonably low dark-noise count rate. The avalanche diode at the anode operates in a low gain analog mode and has no afterpulsing. As a result, these HPMTs can detect single photons continuously at high count rates without gating. The relatively large photocathode active area (1 mm diameter) is also attractive to many applications including laser altimetry, ranging, and free-space communications through the atmosphere. We measured 25% photocathode QE and nearly the same single-photon detection efficiency at 1064 nm wavelength with a dark count rate of 60,000 per second at −22°C. The output pulse width in response to single-photon detection is about 0.8 ns. The maximum count rate exceeded 100 million counts per second and was limited only by the speed of the electronics. The rms timing jitter of the HPMT output was measured to be about 0.5 ns. The jitter is dominated by the electron diffusion time within the photocathode and can be improved by reducing the photocathode thickness at a small loss in photocathode QE. We evaluated several of these HPMTs and detailed measurement results are reported in this paper.