Optical Recording Storage Research Articles

4‐ary 14/16 modulation code for reducing two‐dimensional inter‐symbol interference

Holographic data storage (HDS) can access data in a short amount of time and can also quickly transmit data because HDS records and reads data in units of pages. Thus HDS is regarded as a promising candidate for future optical recording storage systems. Conventional storage systems such as CD, DVD, and HDD have one-dimensional (1D) inter-symbol interference (ISI). However, HDS has a 2D ISI that degrades performance. In this study, to avoid and overcome the 2D-ISI problem, the authors propose a 14/16 modulation code for 4-ary HDS systems which represents 2 bits on each pixel. The proposed 14/16 modulation code allows a bit of unwanted ISI cases in order to raise the code rate, but it has a higher code rate but similar performance compared to a 3/4 modulation code that has no unwanted ISI cases.

Photoinduced Fluorescence Switching of a New Diarylethene and its Application in Optical Recording Storage

A novel unsymmetrical photochromic diarylethene 1-(2-methyl-3-benzothienyl)-2-{2-n-butyl-5-[2-(1,3-dioxolane)]-3-thienyl}perfluorocyclopentene(1O) was synthesized, and its photochromic, fluorescent and optical strorage properties were investigated. The compounds 1O exhibited remarkable photochromism both in solution and in PMMA film, and the results showed that the cyclization/cycloreversion process of the compound was determined to be the zeroth/first order reaction. In addition, this new photochromic system also exhibited remarkable optical storage character.

Synthesis of a Novel Photochromic Fluorescence Switching Diarylethene for Optical Recording Storage

A new unsymmetrical photochromic diarylethene bearing a benzothiophene aryl unit, 1-[2-methyl-5-(1,3-dithiolpentane)-3-thienyl]-2-[2-methyl-3-benzothiophenyl]perfluoroyclopentene has been synthesized, and its photochromic, fluorescence and optical recording strorage properties were investigated. The compound exhibited pronounced photochromic and clear fluorescence switching properties upon alternating irradiation with UV and visible light; the colorless open form with fluorescence character could be regenerated by irradiation with visible light. In terms of potential use for optical storage and readout, this compound displays fluorescence discrimination between its open and closed form. This fluorescence switching could be the basis of a remote control nondestructive readout method.

Efficient Synthesis of a New Unsymmetrical Photochromic Diarylethene for Optical Recording Storage

A new photochromic diarylethene 1a has been synthesized, and its photochromic, fluorescent and optical recording strorage properties were investigated. The compound exhibited remarkable photochromism and clear fluorescent switches both in solution and in PMMA film. This new photochromic system also exhibited remarkable optical recording storage character.

Efficient Synthesis of a New Unsymmetrical Photochromic Diarylethene for Optical Recording Storage

A new photochromic diarylethene 1a has been synthesized, and its photochromic, fluorescent and optical recording strorage properties were investigated. The compound exhibited remarkable photochromism and clear fluorescent switches both in solution and in PMMA film. This new photochromic system also exhibited remarkable optical recording storage character.

Synthesis of a Novel Photochromic Diarylethene and its Application in Optical Recording Storage

A novel unsymmetrical photochromic diarylethene compound bearing dithiol-pentane unit, 1-[2-methyl-5-(1,3-dithiol-pentane)-3-thienyl]-2-[2-methyl-3-benzofuran-yl]perfluoroyclopentene(1a) has been synthesized, and its photochromic, fluorescence and optical recording strorage properties were investigated. The compound exhibited remarkable photochromism and clear fluorescent switches both in solution and in PMMA film. Using diarylethene 1b/PMMA film as recording medium and a linearly polarized 650 nm laser diode for recording and readout, polarization multiplexed image recording can be carried out in this film. The results demonstrated that the diarylethene can be potentially used as polarization multiplexing holographic recording medium.

Prospect of Recording Technologies for Higher Storage Performance

With the progress of information technology (IT), we need more advanced storage devices to accommodate the unprecedented expansion of information and the rapidly changing IT environment. Magnetic and optical recording storage devices, such as hard disk drive (HDD) and optical disk drive (ODD), are the best candidates for satisfying these demands and requirements. For 10 Tb/in2 HDD magnetic recording, we need to develop several advanced and innovative technologies related to the head disk interface (HDI), head/media, servo, and signal processing in current perpendicular magnetic recording (PMR). And, several new read/write mechanisms, such as heat-assisted magnetic recording (HAMR) and bit-patterned media (BPM), are being investigated by many researchers at several institutes around the world. In optical data storage, the page-based holographic data storage system (HDSS) and micro-HDSS are expected to achieve a higher user capacity with beyond terabyte. The near field recording (NFR) system was developed to confirm the feasibility of achieving a multiple terabyte capacity, and currently, through the application of NF nanogap servo system using a flexible media, it is possible to enhance the recording density and data transfer rate together.