Volumetric Optical Recording with Void Marks Using an All-Semiconductor Picosecond Laser

Abstract

We demonstrated volumetric optical recording with void marks in a bulk recording medium using a newly developed all-semiconductor picosecond laser. The laser is compact and has an ultrahigh peak power, which is necessary for practical application of the volumetric optical recording system. We confirmed the laser to be able to record void marks effectively on our recording media. The laser was implemented to our optical drive system as a light source and as much as 30 layer void-mark recording was carried out on the 200-µm-thick bulk recording medium. The total recording capacity was 97 Gbyte and the bit error rates (bERs) were measured to be on the order of 10-4 for most of the layers. We believe that this was a significant step to realize a practical volumetric optical recording system.

Reduction of Interlayer Crosstalk of Multilayer Optical Disc by Using Phase-Diversity Homodyne Detection

“…Reflecting such a situation, multilayer discs holding more than 10 layers have been widely studied in the laboratory stage. [3][4][5][6][7][8][9][10][11][12][13] Ogasawara et al reported 16and 20-layer read-only discs 5) and 16-layer write-once discs 10) with the same density as BD or BDXLÔ. In ref.…”

“…7,8,11) Yamatsu and coworkers reported as many as 30-layer void-mark recording on virtual layers in a bulk recording medium by using an ultrashort pulse laser. 9,12) This recording method does not require physically stacked recording layers and is considered to have a potential to keep the medium cost reasonable. Unfortunately, the density, or capacity per layer D, was considerably low -about one-tenth that of BDXLÔ, presumably because there was difficulty in forming tiny void marks by the use of nonlinear light absorption.…”

Compact Optical Module of Homodyne Detection

“…Multilayer recording is one of the most promising techniques for achieving larger capacity on optical discs, which include multilayer optical discs with a separated guide layer, [1][2][3][4][5][6][7] microholograms, [8][9][10][11][12][13][14][15][16] and void-type microreflectors. 17) However, the signal level in multilayer recording is generally much lower than that of current commercial optical discs due to low reflectivity of each recording layer. Additionally, the higher readout speed results in a larger noise level because a wider bandwidth is required.…”

Robust Adjacent Track Servo System with Linear Positioning Method

“…A multilayer disk without a guide groove can be a largecapacity and price-competitive optical disk. [1][2][3][4][5] However, it requires a more advanced servo control system than the conventional one. 6) Various servo controllers have been studied for optical disk drives to realize higher performance using higher gain [7][8][9][10][11][12] or a feed-forward controller.…”