High-Density Near-Field Readout over 50 GB Capacity Using Solid Immersion Lens with High Refractive Index

Abstract

Dielectric and conductivity spectra of the compound Li 1−x Ni 1+x O 2 (x = 0.03) are reported and analysed. The spectra were recorded for compacted powders within the broad frequency range 10-10 10 Hz at temperatures varying between 210 and 300 K. The evolution of the spectra of the sample with respect to the damage under air allows us to define two regimes: the first one is an interfacial regime and the second a bulk regime. The frequency of crossover (ν co ) between the two regimes lies in the interval 1 × 10 9 and 2 × 10 9 Hz at room temperature. At frequencies below ν co , the spectral analysis shows dielectric relaxations due to interfacial polarization phenomena in the sample. The complex resistivity plots (for ν < ν co ) allowed the determination of the dc conductivity of Li 1−x Ni 1+x O 2 versus temperature. At frequencies greater than ν co , one dielectric relaxation corresponding to small-polaron hopping has been observed. The corresponding relaxation frequency is thermally activated with an activation energy of 0.15-0.16 eV and a pre-exponential factor ν 0 ≈ 3×10 12 -4 × 10 12 Hz, which is of the order of the longitudinal-optical-phonon frequency ν L O . The conduction behaviour is interpreted in terms of hopping of small polarons (holes) on an oxygen network.

Issues in heat-assisted perpendicular recording

“…An FWHM value of 139 nm has been demonstrated for a GaP SIL at 560 nm [15]. An SIL made from high-index S-LAH79 glass has also been demonstrated at 405 nm with an NA of 1.8 [16], corresponding to an FWHM spot size of 115 nm. However, obtaining a 50-nm FWHM optical spot from an SIL with visible light requires a transparent material with a refractive index greater than 4.…”

High-density near-field optical disc recording using phase change media and polycarbonate substrate

“…The top radius of the SIL facing the disc surface is set to be 20 micrometers then the tilt margin for the air gap height of 20nm is +/-0.06 degrees. The conical angle is set to be 70 degrees because the incident light angle of blue laser is 64.2 degrees [4]. The NA of the SIL is designed to 1.84 by using high refractive index glass material.…”

“…The NA of the SIL is designed to 1.84 by using high refractive index glass material. The refractive index of the glass is 2.07 at 405nm wavelength [4]. Proc.…”

Recording characteristics of high-density thin optical disk using near-field optical recording

“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] It can exhibit a large capacity and a highdata transfer rate towards recording next-generation ultrahigh-definition television [i.e., Super Hi-Vision (SHV), 7320 Â 4320 pixels] video signals 17,18) for home-use. Fourfold higher density recording using NFR optical disks with 1.2-mm-thick disks has been reported, 12,14) and studies of larger capacity using multilayer recording using NFR have been reported.…”