In-Oh Hwang

Super-resolution by elliptical bubble formation with PtOx and AgInSbTe layers

The recording and retrieval of signals below 100 nm mark length were attempted with elliptical bubble-type super-resolution technology with platinum oxide (PtOx) and ductile AgInSbTe layers, using the same optical system as that of a digital versatile disk (a 635 nm wavelength red laser system). The carrier-to-noise ratio (CNR) of over 47 dB for 100 nm mark length signals (over 43 dB for 80 nm mark length signals) was obtained, which can be considered as a commercially acceptable level of CNR. The recording mechanism of the sample disk was shown through the transmission electron microscopy cross-section image observation to be by rigid elliptical bubble formation at the PtOx layer located between the AgInSbTe layers. The results of this report represent the potential for a much higher-density storage using the red laser system and a subterabyte optical storage using the blue laser system.

Synthesis and Characteristics of Protective Coating on Thin Cover Layer for High Density-Digital Versatile Disc

This study relates to the optical disc used in the high-density digital versatile disc (HD-DVD) system that uses a high numerical aperture of 0.85 at 405 nm wavelength. The disc has a protective layer formed on the light-incident surface for protection against damage and dust. The synthesis of the UV-curable resinous material, as means of making a protective layer within sufficient margins of thickness variation and optical and mechanical properties, was investigated. In addition, the dynamic characteristics, including reflectivity, fluctuation of the RF signal and noise level, were also investigated.

Signal Characteristics of Super-Resolution Near-Field Structure Disks with 100 GB Capacity

We report the basic characteristics of super resolution near-field structure (Super-RENS) media at a blue laser optical system (laser wavelength 405 nm, numerical aperture 0.85). Using a novel write once read many (WORM) structure for a blue laser system, we obtained a carrier-to-noise ratio (CNR) above 33 dB from the signal of the 37.5 nm mark length, which is equivalent to a 100 GB capacity with a 0.32 micrometer track pitch, and an eye pattern for 50 GB (2T: 75 nm) capacity using a patterned signal. Using a novel super-resolution material (tellurium, Te) with low super-resolution readout power, we also improved the read stability.

Super-Resolution Near-Field Structure with Alternative Recording and Mask Materials

Using a variety of recording materials, such as terbium–iron–cobalt (TbFeCo), tungsten (W), silver (Ag) and silver–zinc (Ag–Zn), the characteristics of super-resolution near-field structure (super-RENS) disks with the reactive diffusion (RD) recording mechanism were investigated. As a new mask material, WOx, which has a high transition temperature, was applied to a super-RENS disk. A combined W recording layer and WOx mask layer achieved much higher carrier-to-noise ratio (CNR), and better thermal stability, compared with AgOx light-scattering-type super-RENS disks.

Random pattern signal characteristics of super-RENS disk in blue laser system

We report the random pattern signal characteristics of the super resolution near field structure (Super-RENS) disk in a blue laser optical system. (Laser wavelength 405 nm, numerical aperture 0.85) We introduced new structure for blue laser system, which results in 43 dB carrier to noise ratio (CNR) at the 75 nm mark length signal (which is equivalent to 50 GB capacity with 0.32 micrometer track pitch) and much better readout stability were obtained. The relatively clear eye pattern, phase locked loop (PLL) state and data to clock jitter of around 20% for a 50 GB (2T:75 nm) random pattern signal were realized.

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.

Signal Characteristics of Super-Resolution Near-Field Structure Disk in Blue Laser System

We report the signal characteristics of a super-resolution near-field structure (super-RENS) disk in a blue laser system (laser wavelength, 405 nm; numerical aperture (NA), 0.85). By introducing a new structure for the blue laser system, a 42.5 dB carrier to noise ratio (CNR) at a 50-nm-mark-length-signal (which is equivalent to a 75 GB capacity with a 0.32 micrometer track pitch and a 1–7 modulation code (Blu-ray disc (BD) format)) and a much higher readout-stability were obtained. Transmission electron inicroscope (TEM) image analysis revealed that the new blue structure has clear diffusion protection barriers produced by continuous Pt particles, which is related to higher CNR and readout stability characteristics.

First Playback of High-Definition Video Contents from Super-Resolution Near-Field Structure Optical Disc

A super-resolution near-field structure (super-RENS) read-only-memory disc with an In–Sb thin film as a super-resolution active layer corresponding to a 50 Gbyte capacity per layer was fabricated. The carrier-to-noise ratio at a pit length of 75 nm exceeded 40 dB and a bit error rate (bER) of the order of 10-5 satisfying the 3.0×10-4 criterion was obtained. To the best of our knowledge, this is the first report on the successful and seamless playback performance of a high-definition video content from the super-RENS disc at a data transfer rate of either 36 or 72 Mbps. The bER results of fixed and adaptive partial response maximum likelihood detections are described.

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.

Phase change materials in Super-RENS disk

Super-REsolution Near-field Structure (Super-RENS) is one of the most promising technologies for a subterabyte optical storage. In this paper, we will report effects of phase change material on the recording and readout characteristics of a Super-RENS disk.