We present results of the feasibility study on photoaddressable polymers (PAPs) applied to optical disc systems. PAPs represent a new class of organic rewritable materials that exhibit a huge signal birefringence (Δ n) at the readout wavelength. By optimizing the disc structure and the readout optics, the signal amplitude is proved to be sufficient for the optical disc systems. A low noise profile and sharp recording profile led to a maximum carrier-to-noise ratio (C/N) of 58 dB and a clear eye-pattern. They also showed a potential for multi-level recording, since the recording was dominated by a pure photon mode.

Since self-cooling devices were first proposed, several materials have been tested for their suitability to be used in them. A self-cooling device requires a high Seebeck coefficient, a low electrical resistivity, and a high thermal conductivity. Here, we report experimental results for single-crystal silicon doped with boron. Samples were fabricated with carrier densities in the range of 2.0×1015 to 1.6×1019 cm-3, and their Seebeck coefficient and electrical resistivity were measured. Silicon with a carrier density of 1.6×1019 cm-3 has a power factor of 4.8×10-3 W/(K2·m) at room temperature. The cooling capability of a self-cooling device was estimated using a one-dimensional model. The results suggest that a self-cooling device based on silicon with a high carrier density can have a higher heat removal performance than a conventional silicon power device of the same size.

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A new ASE filter is presented, consisting of 20 dispersion prisms and two spatial filters. The transmission of the filter is measured with a ring-dye laser. The 1‰ width of the filter is 0.23 nm. The transmission is approximately 80% for the transmitted wavelengths. The rejection is in the order of 10 −5 . The transmission profile is calculated from the index of refraction of the prisms, Snell's law, and the laser waist diameter. The calculated profile fits the measured profile very well.

A feasibility study of a magneto-optical(MO) disk for an NA 0.85 system is presented. The disk noise level in this system was relatively large compared to the conventional NA 0.55 system at the recording density corresponding to this spot size. Two methods were introduced for the improvement. One was the optimization of the groove structure, and the other was the reduction of the metal surface roughness. The former was found to be the typical noise source for optics for a narrower track pitch disk. A DV ashing apparatus was utilized for reduction of the noise. The latter noise source was characteristic for the surface MO recording, and the etching process was found effective for the improvement. By using both these methods, the noise level was drastically decreased, achieving high areal density of 7 Gblinch 2 •

We propose a new disk structure for conventional TbFeCo disks, which is suitable for blue laser light sources, i.e., an additional thin metal layer adjacent to the TbFeCo layer. The metal layer effectively improved a thermal characteristic of the medium, which resulted in a high carrier level even in a relatively high readout power. Using the improved medium, high-density recording was demonstrated in a 407 nm laser and 0.60 numerical aperture (NA) lens system. Despite the decay of the Kerr effect and photocurrent compared to those in an MD DATA2 red system, the new medium achieved an acceptable jitter level at a density of only about 11% lower than that expected from the MTF scaling. This effect was also found to be effective for a red laser with an NA 0.85 lens.

Tripled areal density optical recording was realized with the combination of a high power laser-diode pumped intracavity frequency-doubled Nd:YAG laser (SHG green laser), a low noise GdFeCo/TbFeCo double-layered magneto-optical (MO) disk, and high sensitivity photodetectors optimized for the wavelength of the light source. A high carrier-to-noise (C/N) ratio of more than 48 dB and a bit error rate of less than 3×10-6 by (2, 7) run-length-limited (RLL) mark position recording was obtained at a mark length of 0.45 µm (0.6 µm/bit) for a disk with a 0.9 µm track pitch.