QUADRILAYER MAGNETOOPTIC ENHANCEMENT WITH ZERO KERR ELLIPTICITY

An analytical approach is used to develop a systematic method for designing magneto-optic quadrilayer structures which maximize the signal-to-noise ratio associated with readout systems utilizing differential detection of the Kerr effect. This new technique of optimizing the performance of magneto-optic recording media relies on the possibility of achieving two important requirements. First, the maximization of the Kerr component, and second, the reduction to zero of the phase difference between the Kerr component and the normal Fresnel reflection component. This means that quadrilayer structures can be produced which, for any pre-determined reflectance, will have a maximum Kerr rotation and zero ellipticity. It is also emphasized that the reflectance of the recording surface which maximizes the signal-to-noise ratio is determined only by the levels of electronic and shot noise in the detection system.