Optical Excitation Effects on Spin-Noise Spectroscopy in Semiconductors.

摘要

The effects of laser intensity and laser wavelength on measurements of spin noise in bulk semiconductors are studied with an absorption-based optically excited impurity ionization model. The laser intensity and wavelength dependent electron spin relaxation time illustrates the gradual transition from a near nonperturbative measurement to a perturbative measurement. A strong relationship between the measured wavelength and intensity dependent absorption and the spin relaxation time is observed and is shown to fit well to a simple model. For semiconductors where spin noise has to be measured in the absorption regime, a spin relaxation time related to material properties rather than experimental conditions (e.g., laser intensity, laser wavelength, etc.) can be extracted from perturbative measurements in the limits of long wavelength and the low laser intensity.