Abstract
Spin noise spectroscopy is a powerful technique for studying spin relaxation in semiconductors. Inthis article, we propose an extension of this technique based on optical heterodyne detection of spinnoise, which provides several key advantages compared to conventional spin noise spectroscopy:detection of high frequency spin noise not limited by detector bandwidth or sampling rates of digitizers,quantum limited sensitivity even in case of very weak probe power, and possible amplificationof the spin noise signal. Heterodyne detection of spin noise is demonstrated on insulating n-dopedGaAs. From measurements of spin noise spectra up to 0.4 Tesla, we determined the distribution ofg-factors, Δg/g = 0.49%.