Studies on surface roughening of phase-change optical media

Noise has a strong influence on detected signals, and may be a critical reason that limits the capacity of optical media (M. Mansuripur, ISOM´2001, Fr-L-01, p. 212, 2001). There are three major classes of noise: system noise, media noise and electronic noise. With development of high-density phase-change optical media, it becomes more interesting to study the media noise such as mark irregularity and surface roughening (A. Hirotsune et al, Jpn. J. Appl. Phys. vol. 35, p. 346, 1996; J.M. Li et al, ISOM´01, Th-J-41, 2001; Y. Honguh, Jpn. J. Appl. Phys. vol. 28, p. 115, 1989; T.H. Heong et al, ODS 2001, p. 43, 2001). The surface roughening is an important source of the media noise. This paper investigates the scaling characteristics of phase-change optical films based on the variation-correlation function (VCF) (J.M. Li et al, J. Appl. Phys., vol. 86, p. 2526, 1999). Furthermore, efforts are also put into the influences of the film surfaces with different roughness and the simulated fractal Brownian motion (FBM) surfaces with different Hurst exponents H on the readout performance of the optical media.