OPTICAL AND MAGNETO-OPTICAL PERFORMANCE OF OPTIMIZED DISK STRUCTURES

抄録

  We explore the relative magneto-optic readback performance of three magnetic materials for erasable optical data storage. We modeled the system signal-to-noise ratio (SNR) of optimal film structures incorporating either TbFeCo, a Co/Pt multilayer, or BiDy-substituted FeGa garnet as a function of the wavelength of the reading light beam. The complex indices of refraction and Voigt parameters of the three magnetic storage materials were determined experimentally over the spectral range 300-800 nm by regression fitting of data from variable angle of incidence ellipsometry and normal incidence Kerr spectroscopy to an appropriate optical model. Making specific comparisons of the read back performance at 450, 550, and 800 nm, we find that for the MO materials we have characterized, the performance of TbFeCo is superior to that of either Co/Pt or the garnet at 550 and 800 nm. Only at 450 nm did the Co/Pt give slightly higher SNR than the TbFeCo. The garnet showed improving SNR in passing from 800 nm to the shorter wavelengths, but it had lower performance than the metal films.