Optimization of magneto-optical Kerr setup: Analyzing experimental assemblies using Jones matrix formalism

We present a comparative study on an experimental and theoretical optimization of magneto-optical Kerr setups based on photoelastic modulation and phase sensitive detector methodology. The first and second harmonics, I-omega,I-2 omega, of the reflected light intensity are measured for a CoO/Co magnetic reference film. The magnetic field dependence of the optical off-diagonal Fresnel reflection coefficients r(ps) and r(sp) follows the sample magnetization. Different Kerr setups provide various dependencies of I-omega,I-2 omega on the reflection coefficients and, hence, on the Kerr ellipticity epsilon(K) and rotation theta(K). Jones matrix formalism has been used to analyze the impact of a systematic variation of relative analyzer and polarizer orientations with respect to each other and with respect to the retardation axis of the modulator involved in longitudinal Kerr setups for incoming s-polarized light. We find one particular setup which maximizes I-omega as well as I-2 omega and maximizes the signal-to-noise ratio. Inefficient setups are characterized by I-omega,I-2 omega intensities involving large nonmagnetic contributions of r(p) and r(s). (C) 2008 American Institute of Physics.