Signal and Noise Analyses on Three-Dimensional Volumetric Optical Disks

• Main Authors: Bor-Wen Yang, 楊伯溫
• Other Authors: Han-Ping David Shieh
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/36316078505385031445

博士 === 國立交通大學 === 光電工程所 === 88 === As time goes on, the culture of human being advances, and the impact of high technology on the world becomes more tremendous. The huge information created by people demands higher-speed signal processing and larger-scale data storage. Optical recording media, with merits of high density and portability, become important in human life. To fulfill the requirements of computer, communication, and multi-media applications, higher recording density, higher data rate, and multiple recording functions become the main objectives in developing advanced optical recording technologies. Among the advanced techniques, the super-resolution and three-dimensional optical storage technologies attract more attentions because of their great application potentials. The advanced optical storage technologies can be categorized into two groups: one is to increase the areal density of a single-layer optical disk by employing narrow track-pitch or super-resolution technologies; the other is to multiply the volumetric density of a three-dimensional volumetric optical disk by implementing multiple data layers along the direction perpendicular to the data surface. The thesis is devoted to increasing the areal density of an optical disk by applying pulsed irradiation on super-resolution optical disk, and to promoting the volumetric density and/or extending the application potential by employing multi-layer/multi-functional optical storage technologies. Super resolution is a readout method employing below-diffraction-limited apertures to detect sub-mm data marks. Compared with DC source, pulsed irradiation produces smaller, more regular, and more circular apertures, thus, is more suitable for readout on high-density erasable optical disks. Inducing limited intertrack crosstalk, smaller aperture jitter, and lower aperture wall noise, nanosecond-order laser pulses yield better readout performance and higher areal density. Besides inter-symbol and inter-track crosstalk, interlayer crosstalk is induced in reading a volumetric optical disk. To improve the signal-to-noise ratio of a multi-layer optical disk, the suppression of interlayer crosstalk is essential. The readout process on dual-layer optical disks was analyzed to study the source of interlayer crosstalk and the effect of interlayer crosstalk on readout characteristics. Experiments were conducted to correlate with the analytical results. Schemes were reported to suppress interlayer crosstalk to promote the volumetric density of a multi-layer optical disk. Employing multiple data layers of different recording functions on an optical disk further extends the application of optical recording to multi-functionality. A semi-transparent read-only layer and an erasable phase-change layer were adopted in a dual-functional optical disk called PC-ROM (Phase-Change/Read-Only-Memory). The PC-ROM was optimally designed to be with writing sensitivity compatible to that of PD and readout sensitivity compatible to that of CD-ROM. With advanced technologies such as super-resolution and volumetric optical recording, the storage capacity and application potential of optical disks can be further improved.