Xiangshui Miao

Investigation on Super-Resolution Near-Field Blu-Ray-Type Phase-Change Optical Disk with Sb2Te3 Mask Layer

Super-resolution near-field phase-change Blu-ray-type optical disks with a mask layer of Sb2Te3 were studied theoretically and experimentally with a laser wavelength of 405 nm and a numerical aperture (NA) of 0.85. The modulation transfer function (MTF) was calculated and the thermal performance was simulated by the finite element method. Super-resolution near-field phase-change Blu-ray-type optical disks with different structures were fabricated and measured. It was shown that the thermal shield layer was helpful in reducing recorded mark size and improving readout stability. Recorded marks as small as 16 nm were observed. The relevant mechanism was discussed.

Study of the Multi-Level Reflection Modulation Recording for Phase Change Optical Disks

Multi-level reflection was obtained on rewritable phase change optical disks with a static tester using different laser amplitudes. Different levels of input power amplitude give rise to different reflection levels. In order to study the mechanism for forming the multi-level reflection, partial crystallization effect and size effect were studied. The partial crystallization effect was studied using differential scanning calorimeter (DSC) measurement and X-ray diffractometer (XRD) measurement. The size effect was studied by simulation and measurement. Based on the simulation and experimental results the combination of size effect and partial crystallization effect is proposed as the main reason to cause the multi-level reflection. This model can be used to analyse the writing, erasing, and overwriting processes of multi-level reflection modulation recording.

A New Structure of Super-Resolution Near-Field Phase-Change Optical Disk with a Sb2Te3 Mask Layer

A super-resolution near-field phase-change optical disk with a new mask layer of Sb2Te3 was studied. The disks were fabricated and characterized. The problem of thermal stability for the conventional Super-RENS (Super-Resolution Near-field Structure) was studied for the first time. In order to solve the problem of poor thermal stability, two new structures with a thermal shield layer that can significantly improve thermal stability were proposed, fabricated, and analyzed. Recording marks as small as 56 nm were observed.

Study of the Superlattice-Like Phase Change Optical Recording Disks

Superlattice-like phase change optical disks, where the recording layer consists of alternating thin layers with two different phase change materials of GeTe and Sb2Te3, have been fabricated. The optical and thermal properties were simulated and measured. Samples were measured by X-ray diffraction (XRD) after annealing. The peaks of Ge2Sb2Te5 were observed, which indicates that Ge2Sb2Te5 was formed at the interface between GeTe and Sb2Te3. The recording, erasing and overwriting properties were investigated. The signal differentiation in writing, reading and erasing was observed at the pulse width of 7 ns, which indicates that the superlattice-like structure can effectively shorten the crystallization time. The overwriting cycle was measured using a static tester. Within 10000 times no significant change in the modulation amplitude was observed.

Super-Resolution Near-Field Phase Change Disk with Sb70Te30 Mask Layer

Super-resolution near-field phase change optical disks with a new mask layer of Sb70Te30 were studied. Disks with two different structures were analyzed using optical and thermal simulation methods. The simulation results showed that the optical disk exhibited maximum response when nearly half the laser spot was covered by the mask. The fast response depended on optimizing both the disk structure and reading power to match a certain speed because the effect of super-resolution near-field structure (super-RENS) was related to the position between the laser beam and the hole formed in the mask layer. Experimental results showed that the disk with a thermal shield layer, which was inserted into the dielectric layer located between the mask layer and the phase change layer, demonstrated a better thermal stability than the disk without the thermal shield layer. This is in good agreement with simulation results. Recording marks as small as 62 nm were observed.

Multispeed rewritable optical-recording method with an initialization-free phase-change disk.

A new method of multispeed rewritable optical recording is presented. An initialization-free phase-change optical disk is proposed as a candidate for multispeed rewritable optical recording. The simulated results of the initialization-free disk at different linear velocities show that the cooling rate increases from approximately 18.69% to 37.96%. A model that combines the crystallization acceleration effect due to the additional layers and the rapid cooling rate due to the initialization-free disk structure is proposed as the physical mechanism of the multispeed recording method with an initialization-free disk. The dynamic optical-recording properties of the initialization-free DVD-RAM disk at different recording speeds shows that the initialization-free phase-change optical-recording disk is compatible with a broad range of recording speeds from 3.49 to 12.21 m/s.

Near-Field Characteristics and Signal Enhancement of Super-RENS Disk with Metal Nanoparticles

Investigation focuses on near-field characteristics and surface plasmon (SP) induced with uniform- and none-uniform-size Ag nanoparticles in mask layers of super-RENS structures. Signal enhancement mechanism of the super-RENS disk is discussed.