Jae-cheol Bae

Bit Error Rate Characteristics of Write Once Read Many Super-Resolution Near Field Structure Disk

We firstly report the bit error rate (bER) characteristics of a super-resolution near-field structure (super-RENS) write-once read-many (WORM) disk in a blue laser optical system, (laser wavelength 405 nm, numerical aperture 0.85) with a carrier-to-noise ratio (CNR) at the 75 nm mark (50 GB Capacity) of 47 dB and a low frequency noise of approximately 20 dB. The recording state should be precisely controlled by an adequate writing strategy for bER measurement. Together with the above conditions, using the frequency-dependent gain controlled equalization (EQ) and advanced partial-response maximum likelihood (PRML) technique, bER of 10-3 order at 50 GB was obtained.

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.

Improvement of Noise Characteristics in Super-Resolution Near-Field Structure Disc

The research interest in super-resolution near-field structure (Super-RENS) technology is shifting from the signal intensity (carrier-to-noise ratio, CNR) to the signal uniformity (jitter or bER). To achieve uniform signal characteristics, it is important to reduce signal fluctuation in the super-RENS disc. In this study, we investigated the relationship between signal fluctuation and low-frequency noise (LFN), and analyzed the LFN increase in recording and readout processes. It was found that signal fluctuation had a close relationship with LFN. It was also found that certain recorded mark shapes, such a bubble shape, and high readout power increased the LFN during recording and readout processes of a super-RENS disc. Therefore, using non bubble-type recording material and low super-resolution readout material, we markedly improved the LFN of a super-RENS disc.

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.

Error rate improvement of super-RENS random signal with the minimum mark length of 75nm in 405nm 0.85 NA system

We report the error rate improvement 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) We used a disk of which carrier level (CL) of 75nm is improved from -26.3 dBm to -19.0 dBm. We controlled the equalization (EQ) profile characteristics and used the adaptive 5 symbol write strategy and advanced high tap partial-response maximum likelihood (PRML) technique in order to improve the bit error rate (bER) characteristics of the super-RENS random signal. As a result, we obtained bER of 10-4 level with new signal processing techniques and bit error analysis process. This result shows high feasibility of super-RENS technology for practical use in the near future.

Error Rate Improvement of 75 nm Super-RENS Signal in 405nm, 0.85 NA System

We report the error rate improvement of super-resolution near field structure (Super-RENS) write-once read-many (WORM) disk at a blue laser optical system. (Laser wavelength 405 nm, numerical aperture 0.85) We used a disk of which carrier level of 75 nm is improved. We controlled the equalization (EQ) characteristics and used the adaptive write strategy and advanced partial-response maximum likelihood (PRML) technique. We obtained bit error rate (BER) of 10-4 level with new signal processing techniques. This result shows high feasibility of super-RENS technology for practical use