Optical sum-frequency generator based on coupled waveguides

Abstract

A method is described to extend the usefulness of photon correlation computers beyond the low photon density regime and through the photon pile-up regime, thereby permitting application to signals that are strong by the standards of photon correlation, but noisy by the standards of conventional Doppler signal processors. The technique correlates the pulse train obtained from the zero crossings of the analogue signal formed by filtering the photon-resolved signal. The correlation and its spectrum contain strong peaks that define the Doppler signal frequency.