Lock-in detection of single photons after two-step frequency conversion.
We report on cascaded frequency conversion at the single-photon level, consisting of a downconversion from the red (738 nm) to a telecom band (1403 nm) and the reverse upconversion process in the same nonlinear crystal. Detecting the converted single photons suffers from a large noise floor. We were able to recover the signal by implementing a lock-in analyzer technique in the data postprocessing.
Fachrichtung 7.2 (Experimentalphysik), Universität des Saarlandes, Saarbrücken 66123, Germany.
Andreas
A
Lenhard
Sebastian
S
Zaske
Christoph
C
Becher