<title>Extended dynamical range solid state photon counter</title>

Abstract

The paper describes the new achievements in an all solid state photon counting technique with picosecond resolution. The extended dynamical range has been achieved: the dependence of the detection delay on the detected signal strength - the time walk -has been compensated within several orders of optical signal strength. The principal application of the detector is the millimeter resolution satellite laser ranging. The detector is based on silicon avalanche photodiode pulse biased above its break voltage. The external gating and avalanche active quenching electronics is used. The time walk of the avalanche photodiode is of the order of hundreds of picoseconds in the dynamical range of single to one hundred photons input signal strengths. The additional electronics circuit has been developed to compensate for the time walk: the input optical signal strength influences the avalanche current build up time,the maximum build up time difference is 20 psec within the dynamical range 1:1000. This time difference is sensed, stretched by the factor of ten. The stretched time interval is applied, with the negative sign, as a correction to the detector propagation delay. The detector ultimate timing resolution, temporal stability, dynamical range and its dependence on the input laser pulse length have been investigated in detail. The fieldable version of the detector is been used for satellite laser ranging purposes. The timing resolution of the entire detector better than 20 picoseconds r.m.s., the maximum dynamical range > 1000:1 with the item walk bellow +/- psec have ben achieved, the results are presented. The additional applications in spectroscopy, biophysics, rangefinding and fiber optics may be considered.