Kazuyuki Hirooka

Improved performance in coaxial holographic data recording

We describe a coaxial holographic recording system for achieving high recording density. We implement several techniques, such as an objective lens with high numerical aperture (NA), high capacity page data format, a random binary phase mask, and an optical noise reduction element. Our system successfully realizes a hologram recording/retrieving at a low diffraction efficiency less than 2.0 x 10(-3) and achieves a raw data density of 180 Gbit/in.(2), thus demonstrating the potential of a coaxial holographic system for high-density optical storage systems.

415 Gbit/in. 2 recording in coaxial holographic storage using low-density parity-check codes

We have applied LDPC codes into our coaxial recording system, and revealed its fundamental characteristics. In addition, by applying the E(16, 3, 8) code and optimizing optical conditions, we have successfully improved the recording density, achieving the raw data density of 415 Gbit/in.2.

Linear Reproduction of a Holographic Storage Channel using Coherent Addition of Optical DC Components

A holographic data storage channel is normally a nonlinear channel; however, it can be made linear. Using coherent addition of DC components in the reproduction process and calculating the square root of intensity, we can retrieve a linearly reproduced signal. Our simulation results revealed that a conventional equalizer works well to suppress interpixel interference so that a higher recording density can be achieved.

High Density Recording of 270 Gbit/in.2 in a Coaxial Holographic Recording System

An improvement of the recording density in a coaxial holographic recording system is described. We employ a new optical setup into our coaxial system, where the numerical aperture (NA) of an objective lens and the data capacity in one page increase up to 0.85 and 135 kbits, respectively. The recording performances are evaluated experimentally and numerically. The obtained results demonstrate that implemented techniques successfully improve the recording density by a factor of 1.5, achieving a raw data density of 270 Gbit/in.2.

Optical System Designed for Coaxial Holographic Recording on Continuously Rotating Disc

This study introduces the specified objective lens and the new image position servo system to the coaxial holographic recording system. The validity of these technologies is verified analytically and experimentally

Linear Signal Processing for a Holographic Data Storage Channel Using Coherent Addition

A linear channel model and a linear signal processing technique are available for a holographic data storage channel when our proposed coherent addition technique is applied to the reproduction process. As a result, the signal-to-noise ratio (SNR) after zero-interpixel-interference (IPI) equalization is markedly improved. Moreover, we can achieve a higher transfer rate at a lower oversampling rate owing to the almost ideal linearity of the reproduced signal.

Development of a coaxial-type holographic disk system with a small drive

We have developed a coaxial-type holographic disk system with a small drive. We achieved stable operation without use of a vibration-isolating table, with a 91-Mbps data-transfer rate for recording and retrieving using LDPC code.

High-Speed Data Recording and Retrieving Using the Image-Stabilizing Technique in a Coaxial Holographic Disk System

107 Mbps and 92 Mbps data-transfer rates for recording and retrieving, respectively, have been achieved by improving the coaxial holographic disk system using the IS technique.

Development of a Coaxial type Holographic Disc Data Storage Evaluation System, Capable of 500-fps-Consecutive Writing and Reading

A coaxial type holographic data storage evaluation system, capable of 500-fps-consecutive writing and reading, has been developed, whose light source is a semiconductor blue laser diode. This is realized by an image-stabilizing technique.