Multi-dimensional Optical Storage by Duanyi Xu

Author:Duanyi Xu
Language: eng
Format: epub
Publisher: Springer Singapore, Singapore

Due to the drive prototype was abrogated complex apochromatic objective lens, so its focus size has obvious chromatic aberration and have to adopt super-resolution technology to control and reform the focus of three wavelength lasers. The super-resolution technology has been introduced in Chap. 4 of this book. It’s most important application is in multi-wavelength optical storage indeed. Except inorganic materials, some organic materials can be used to super-resolution structure (super-RENS) as the non-linear photochromic materials for example to utilize the super-RENS optical data storage in practice. The super-RENS mask layer has super-RENS effect to get smaller spots on the disc and increase the storage intensity. The photochemical super-resolution structure (P-super-RENS) mask was developed in OMNERC in 2000. Compared with inorganic materials super-RENS, P-super-RENS has many advantages, such as higher sensitivity, intensity and better manufacturability. Based on this technology, the 3T run-length is reduced from 0.84 to 0.48 μm and the spacing is reduced from 1.6 to 0.85 μm with good quality of the signal. So, P-super-RENS mask was adopted to multiwavelength and multilevel storage. The main reason is that can make the spots of indifferent wavelengths to be a smaller uniform size and increase the storage intensity of course.

The principles and structure of the disc with the P-super-RENS mask is shown in Fig. 5.13. Comparison with conventional discs, the P-super-RENS mask is added between substrate and the recording dye layer. When the laser beam scan the initialized P-super-RENS mask layer (colored), the irradiated zone to be bleached with a photochemical reaction only. Therefore other reading or writing lasers beam can penetrate mask layer to recording layer. Since the P-super-RENS mask layer has a threshold for bleached reaction, so the effective spot on P-super-RENS mask layer is smaller than the original diffraction spot and therefore achieved the super-resolution as shown in Fig. 5.13a. The reflectivity of bleach zone is increased rapidly as in Fig. 5.13b.

Fig. 5.13The structure of the disc with a P-super-RENS mask

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