SPAD Detector Package for Space Born Applications

The SPAD detector package for the space born applications is under development with the envision of several space missions related to time transfer by laser light, one way laser ranging and laser transponder. The requirements on detector package are rather different from the ground based laser ranging systems [1]. Recently, the most challenging task is the development of the solid state detector package capable of non gated operation. The existing detector configurations do not permit non gated operation due to the excess dark count rate of the detector, which is caused by strong after pulsing effect. The after pulsing effect is strongly influenced by the quenching circuit. The longer it takes to quench the avalanche after a photon detection, the stronger is the after effect. The conventional active quenching circuits have a loop delay in the range 20-30 nanoseconds. We have developed a new active quenching and gating circuit with the loop delay shorter than 3 nanoseconds. It enables to operate the K14 series SPAD detectors in the non gated mode with the acceptable dark count rates and timing resolution, as well. The circuit permits to operate the detector 0.1 to 1.1 Volt above its break voltage. Using the chips with 40 um in diameter, the dark count rates below 15 kHz and a timing resolution of 30 picoseconds have been obtained at a room temperature and non gated operation. The detection chip has been biased 1.0 Volt above its break voltage. The optional gating permits to gate on/off the detector extremely fast. The risetime of the sensitivity from 109 photons to a single photon level is below 80 psec, the total rise and overshot times are below 140 psec. The compact and rugged solid state photon counting detector package capable to operate in both non gated and gated modes has been developed. The dark count rate is 10 Hz to 10 kHz within the temperature range of –60 to +20 Celsius, the timing resolution is 30 psec. The detector mass is 30 grams, its power consumption is below 400 mWatts. The detection chip has been space qualified for previous deep space missions [2]