Intensity fluctuations and photoelectric mixing of light beams

Photoelectric mixing in a photodiode is used In this work as a statistical spectroscopic tool. A number of experiments were performed to determine the fluctuation spectrum generated by this process and the statistical properties of the light which might be deduced from the data. Due to practical limitations in attainable temperatures, blackbody sources were not able to produce an observable mixing above shot noise. Experiments were also carried out using line spectra from gas discharge lamps. The best source available was a 300 W Xenon lamp, emitting lines in the red, which under optimum conditions produced excess current fluctuations equal to 60% of shot noise. The observation of photoelectric mixing losing a gas laser source has already been reported in the literature, but the Gaussian distributed electric field model usually applied does not fit the experimental results. A new model was proposed in this thesis which considers the laser light as a narrow band of coherent light embedded in a relatively broad band of spontaneous light. Mixing between the signal and the spontaneous emission was considered to be the only observable effect due to experimental limitations. This model appeared to fit the data and gave some information about the statistical properties of the laser beam.Science, Faculty ofPhysics and Astronomy, Department ofGraduat