Optimization of the signal-to-noise ratio for photoreflectance spectroscopy

The amplitude and the signal-to-noise ratio of photoreflectance (PR) spectra are experimentally and theoretically investigated as a function of the pump and probe intensity. The model calculations of the PR amplitude and the signal-to-noise ratio based on a simple transport model taking the shot noise of the photodetector as the only noise source confirm the experimentally observed dependencies. Increasing the probe light intensity leads to a decrease of the absolute PR background noise. At the same time, the PR amplitude decreases. This may, in particular for comparable probe and pump intensities, result in a decrease of the signal-to-noise ratio. (C) 2001 American Institute of Physics.