Optical heterodyne detection of magnetic resonance in semiconductor heterostructures

We describe the first application to semiconductor heterostructures of a new microwave-frequency optical heterodyne technique which enables electron spin resonance (ESR) spectra to be detected through coherent Raman scattering. Under appropriate conditions, the technique is several orders of magnitude more sensitive than conventional ESR, has several orders of magnitude greater spectral resolution than other magneto-optical techniques and has the advantage of optical selectivity. The approach is based on an optical double heterodyne method of detecting the coherent changes induced in a Raman scattered laser beam when magnetic resonance occurs in the scattering centre. In the present report we demonstrate its use to study detect the spin resonance of electrons in epitaxial layers and in quantum wells. A comparison with the results of spontaneous spin-flip Raman scattering on the same samples is presented.