This work presents a thermal analysis that explains experimental observation in all-optical magnetic recording (AOMR).
An integrated model is used to describe thermal processes at different time scales in AOMR. The formation of magnetic
marks is discussed and implemented by developing a simulator based on 3-dimensional finite element method (FEM).
The simulator is able to carry out thermal analysis of the thin film media and is a useful tool for design of AOMR media
structure, especially for the thermal sink layer.
An integrated analysis tool of optical system and media which combines system with media analysis of the discs is
developed in this project. This software has been used to study the influence of disc tilt, cover layer thickness and
scratches on high density recording, which show that it provides a powerful tool in practical applications.
Two structures super-resolution near-field phase-change optical disks with masks Sb2 Te3 layer and a
thermal shield layer in front of the mask layer on Blu-ray substrates were studied theoretically and
experimentally. Optical simulation was conducted and the modulation transfer function (MTF) was calculated.
MTF calculation results has revealed that the super-RENS optical disk exhibited the maximum response when
nearly half of the laser spot was covered by the mask. The thermal simulation was used to find the optimum
condition meaning that half of the laser beam is covered by the aperture on the mask layer. The recording signal
and thermal stability on different structures were measured and analyzed. The simulation results are in good
agreement with the experiment results.
A method of high-density optical disk structure design using computational electromagnetic FDTD analysis is proposed. A staircase method is used to simulate the realistic sidewall geometrical structure of the land-groove of phase-change optical disk. The phase-change materials appear as different optical characteristics under irradiation of different frequency laser beam. Materials models in the FDTD scheme have been studied to solve the computational instability. Using this FDTD method, the structures of the phase-change optical disk with blue laser and high-NA system are investigated.
The Sb film is proposed as new absorption control layer for high-density phase-change optical disk. The computer simulation results show an absorption control layer in a phase-change optical disk can improve the thermal balance and direct overwriting properties of disk, and Sb film as an absorption control layer is better than Si and Ge films. The experiment results show Sb is a good absorption control layer of high-density phase-change optical disk.
Multi-level recording on rewritable phase change optical disk was studied using a simulation and experiments. The possibility of using multi-level reflection effects to increase the storage capacity was considered using a computer simulation software called phase change optical disk design. Optical and thermal simulations were carried out on disks with phase change material GeSbTe to study its performance. Using a suitable disk structure, the mark shapes of various sizes that give rise to multi-level reflection effects were written on the disk and examined. In order to solve the problem of the difference in the absorption between the crystalline and amorphous states, a thermal compensation layer of Sb was used. Simulation and experiment results have shown that the effect of the difference can be significantly reduced by the thermal compensation layer.
The development of phase change recording is spurred by the demand of high capacity, low cost and rewritable optical data storage. In phase change optical disk, recording and erasing are achieved by laser heating that induces the crystallographic structural changes in the media. The difference in reflectivities of crystalline and amorphous states determines the information stored. Hence the dependence of optical and thermal effects arising from the laser irradiation on the disk needs to be thoroughly investigated. In today’s competitive marketplace, companies are looking into ways of producing better product at lower cost and shorter development time. Thus the capability of performing interactive computer modeling and analyses of the optical disk becomes inevitable to achieve these ends.
A new thermal model to study the laser induced temperature profile of a multilayered phase change optical recording disk is proposed. The new model considers the thermal effect generated by both the transmission and reflection light. The calculation formulae are listed. The model is used to simulate the Ge2Sb2Te5 phase change optical disks with five layers structure. In order to study the differences between the new and existing models, simulations are carried out using both models and the differences are compared. The differences get larger as the phase change layer becomes thinner. It is also revealed that the differences get larger as the wavelength becomes shorter. The idea proposed in this paper is also suitable for the analysis of magneto-optical disks as well as for improved accuracy in the measurement of thermal parameters.
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