• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.411-412
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• 2008

• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.116-121
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• 2003

We have observed a nonclassical effect in a fourth-order interference experiment with the photon pairs produced by parametric down-conversion and the Hong-Ou-Handel interferometer. For interfering classical fields with orthogonal polarizations, the visibility can be no larger than 50%, and it depends on the ratio of the two beam intensities. It is found that not only is our observed visibility of 85％ well above 50％, but it is also independent of the two beam intensities in coincidence measurements made in a two-photon polarization correlation experiment.