Analysis of Near-Field Method for Optical Data Storage using Microstrip Probe under Illumination and Illumination-Collection Mode

摘要

Results of numerical simulation of near-field optical data storage using microstrip probe are presented. Simulation is carried out on the basis of the finite-difference time-domain method. Features of the information reading process from the ROM and RW (based on the phase transmissions of Ge_2Sb_2Te_5 film) formats of optical discs under illumination and illumination-collection mode are analyzed and considered. Mathematical modeling has shown that the signal from the ROM-format disc under illumination mode, despite the fact that the probe has a significant far-field transmission coefficient, has a large crosstalk and small spatial resolution (significantly worse than a size of probe aperture). Unlike illumination mode, signal under illumination-collection mode (pure near-field method) has a resolution close to the size of the aperture, good amplitude and contrast, as well as relatively low crosstalk. However, information reading under illumination-collection mode from RW-format disc is not able to get the same good quality signal. Therefore the further optimization of the method is required to improve the signal quality of RW format.