Chong-sam Chung

Error Rate Reduction of Super-Resolution Near-Field Structure Disc

We report the error rate improvement of super-resolution near-field structure (super-RENS) write-once read-many (WORM) and read-only-memory (ROM) discs in a blue laser optical system [laser wavelength (λ), 405 nm; numerical aperture (NA), 0.85]. We prepared samples of higher carrier level WORM discs and wider pit width ROM discs. Using controlled equalization (EQ) characteristics and an adaptive write strategy and an advanced adaptive partial response maximum likelihood (PRML) technique, we obtained a bit error rate (bER) of 10-4 level. This result shows the high feasibility of super-RENS technology for practical use.

New Data-Reproducing Scheme for Higher Density Blu-ray Disc

A new data-reproducing scheme is presented and implemented by field programmable gate array (FPGA) for higher density data reproduction on a commercial Blu-ray Disc. By introducing a signal waveform phase detector, the phase locked loop (PLL) circuit shows good performance against the inter-symbol interference (ISI) effect. From the experiment results, the new scheme can be used to reproduce data with a linear density of 40 GB using a commercial single-layer Blu-ray Disc.

Approach to high density more than 40GB per layer with Blu-ray disc format

We report the new data reproducing scheme for high density over 40GB per layer with a commercial Blu-ray recordable disc. bER of 10-5 and 10-4 with 42.5GB and 45GB were experimentally obtained respectively using this new data reproducing scheme which shows the possibility of achieving 50GB with a commercial single-layer Blu-ray disc. We also propose a new evaluation parameter which is necessary for high density.

Stability enhancement of super-RENS high temperature readout signal

We report the readout stability improvement results of super-resolution near field structure (Super-RENS) write-once read-many (WORM) disk at a blue laser optical system. (Laser wavelength 405nm, numerical aperture 0.85) By using diffusion barrier structure (GeSbTe sandwiched by GeN) and high transition temperature recording material (BaTiO3), material diffusion of phase change layer and recording mark degradation were greatly improved during high power (Pr=2.0mW) readout process up to 1X105 times.

Experimental and Theoretical Analyses of Cross-Write for In-Groove and On-Groove Recordings

To determine the recording area for groove recording, it is necessary to measure the characteristics of the in-groove and on-groove areas and analyze the reason for the difference, if it exists. In this study, the direct-overwriting jitters with cross-talk and cross-write are measured simultaneously, and a theoretical analysis using finite difference time domain (FDTD) of the difference in the in-groove and on-groove areas is subsequently performed.

Optical Storage System for 0.4 mm Substrate Media Using 405 nm Laser Diode and Numerical Aperture 0.60/0.65 Objective Lens

The most important application of the blue-laser optical storage system is the recording high-definition digital broadcasting. For this application, the next-generation blue laser optical storage system requires a data capacity of at least 2 h of a digital broadcasting data stream with a data transfer rate of 23.5 megabits per second (Mbps). In addition to the capacity goal, system compatibility with the conventional digital versatile disc (DVD) system as well as the compact disc (CD) system is important. In order to satisfy the requirements of blue-laser optical storage, a system for media with a substrates thickness of 0.4 mm was proposed, and improved molding technology, crosstalk cancellation technology, dynamic tilt compensation technology and quadrature phase shift keying (QPSK) modulated wobble addressing method were developed for the system. We confirm the feasibility of the proposed system for media with a 0.4 mm substrate using a 405 nm blue laser diode and objective lens with a numerical aperture (NA) of 0.6 (0.65 for rewritable system).