Reading Characteristics of Phase Change Optical Disks Using a 430nm SHG Blue Laser

Abstract

Feasibility of reading a phase change optical disk at wavelength of 430nm is studied in order to realize high density rewritable optical media. A second harmonic generation (SHG) blue laser was adopted as an optical source. To obtain high carrier to noise ratio (CNR), structure of a phase change optical disk was optimized for blue wavelength region. As a result of reading marks written at wavelength of 680nm, recording density was advanced in proportional to spot size. A CNR of 48dB at the mark length of 0.35μm was achieved at a wavelength of 430nm.