Photocounts and laser detection of weak optical signals
Prokhorov General Physics Institute of the Russian Academy of Sciences, ul. Vavilova 38, Moscow, 119942, Russian Federation
The nature of photocounts arising in detectors exposed to highly coherent laser radiation is discussed.
It is shown that the spatial localization of a photon allowed in quantum
electrodynamics fails to account for the effect observed and
that the Coulomb instability of a low electron flux in a photodetector can be the explanation. With detectors utilizing nonfree electrons, namely, electrons bound in atoms, ions,
molecules, etc., weak optical signals can be detected with laser
radiation without photocounts, in other words, at a suppressed
shot noise. A basic scheme for a laser detector using bound
electrons is suggested.