Abstract:
An investigation is made of the feasibility of absolute measurements of the brightness of light from the signal-to-noise ratio M of a parametric frequency converter with reflection and absorption in a nonlinear crystal. A model of a plane-parallel layer and a constant monochromatic pump source of frequency ω0 is used. Equations are derived to describe the transmission and reflection of waves with frequencies ω1 and ω2=ω0–ω1 in the layer. The resultant four-dimensional scattering matrix determines the quantum noise of the converter in accordance with the "nonlinear" Kirchhoff law. It is found that the number of photons per mode N in the incident light is equal to M multiplied by a correction factor close to unity, which depends on the absorption coefficient and on the refractive index.
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