Abstract

Measurements have been made of the rate at which signal photons are produced in a nonlinear crystal in the process of parametric downconversion, when a coherent light beam from a He:Ne laser is injected into the crystal in the direction of the conjugate-idler photons. The latter provides a stimulating field for the downconversion. When the phase matching condition inside the nonlinear medium is satisfied, the rate of downconversion is enhanced by the presence of the He–Ne laser beam by a factor of the form 1 + βI_i, where li is the intensity of the He:Ne laser beam. The effect of defocusing either the pump beam or the He–Ne idler beam is investigated. Possible use of this phenomenon to study the photon amplifier with single-photon input will be discussed.

© 1990 Optical Society of America