Estimation of thermal conductivity of magneto-optic media

We describe a method to estimate the thermal conductivity of the substrate, the dielectric layer, and the magneto-optic (MO) layer of MO recording media. The method relies on the disappearance of the polar Kerr rotation above the Curie temperature of the MO layer. We obtain the thermal conductivities by taking into account the differences in the heat diffusion behavior under different sized focused spots. The results are reliable to better than 5% accuracy. [C] 2000 Optical Society of America OCIS codes: 210.3820, 210.4770, 120.6810.