Optical Mixing of Coherent and Incoherent Light [Letter to the Editor]

The development of maser sources of intense monochromatic light has opened a new field of experimentation in optics where nonlinear terms in the optical polarizability of transparent piezoelectric materials make possible the generation of optical harmonics
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and the mixing of light waves having different directions of propagation
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and freqency.
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In this previous mixing experiments the intense, relatively coherent outputs of optical masers were used. We report here the mixing of a ruby maser signal with spectral lines of a mercury lamp which are quite broad and relatively weak.