Anticorrelated light switching in an optical loop system

Abstract

We have demonstrated anticorrelated light switching between multiphoton transition channels in a nonresonant double-Λ system. Two-color probe transitions, using rubidium D1 (795 nm) and D2 (780 nm), were included in our double-Λ system. In anticorrelated light switching, one of two probe transitions is selected as transparent while the other is selected as opaque. In this configuration, we observed completely different behavior from that seen in a resonant double-Λ system, in which both probe transmissions are transparent or opaque simultaneously. Furthermore, we observed a noise correlation between two-color probe transmissions when the phase fluctuation of the two probe lasers was converted to the intensity fluctuation. The relative phase fluctuation between the two probe lasers induced an anticorrelation between the intensity noises of two probe lasers in a nonresonant double-Λ system, while a correlation was induced in a resonant double-Λ system. The intensity fluctuation (correlated or anticorrelated) was easily controlled by detuning the double-Λ system. The noise anticorrelation effect is clearly interpreted as arising from the anticorrelated light switching in a nonresonant double-Λ system. This system can be used for noise control as well as optical switching between incoherent two-color laser lights.