Analysis of Magneto-Optic Readout with Circular Polarized Light

This paper presents a new design for magneto-optical pickups which detect the phase shift of circularly polarized light instead of the rotation of plane-polarized light. The use of a polarizing beam splitter and a quarter-wave plate enables a theoretical efficiency of 100%. Efficiency is important not only in order to reduce the laser power when recording, but also to avoid reflected light which would interfere with the laser output. We discuss the theory of readout from circularly polarized light and describe an experiment on reading from a rare earth-iron garnet magneto-optical disk. In conclusion, we discuss the advantages and drawbacks of such a reading method.