Experimental test of the effective-photon hypothesis

The effective-photon hypothesis postulates a photon energy variable with light intensity according to a relation of the form =hv/[1–₀f(I)]=hv₁. This hypothesis has been subjected to direct experimental test. A Mach-Zehnder interferometer is illuminated with aQ-spoiled Nd:glass laser and the time history of the interference fringes is recorded with an image converter camera. The experimental results show that indeed the laser pulse is not monochromatic and that a large frequency change occurs with light intensity. In addition, the analysis of the results indicates that the principle of conservation of energy is not in contradiction with the hypothesis of effective photon, provided photons can exchange energy among themselves.