Readout Scheme by Pulsed Irradiation Center Aperture Detection on Magnetically Induced Super Resolution Magnetooptical Disks

Abstract

Magnetically induced super resolution (MSR) is used to read “below-diffraction-limit” recording marks on magneto-optical (MO) media. A nanosecond-order laser pulse irradiated onto MO media can create a quasi-circular temperature profile, thereby yielding a quasi-circular sub-µ m aperture to effectively derive a readout signal from sub-µ m marks recorded on the disks. In this study, the pulsed irradiation and conventional DC readout methods are applied to a MO disk with a center aperture detection (CAD) structure to quantitatively evaluate their readout performance. The size and shape of the effective aperture, jitters due to readout parameters, and aperture wall width generated are studied. The feasibility of the pulsed irradiation readout is then assessed.

Carrier-to-noise ratio improvement with pulsed-laser readout on magnetically induced superresolution by center aperture detection disks

“…When MSR-CAD disks are spinning at high velocity, the aperture produced by, dc laser irradiation is not circular but tear-drop in shape, thus complicating signal processing for the asymmetric readout signal [S]-[71. The pulsed-laser readout scheme [6], [7] was therefore proposed to improve the readout characteristics of MSR-CAD disks. By applying thirty-nanosecond pulsed-laser irradiation, the created quasi-circular aperture can detect subpm sized recording marks with higher carrier-to-noise ratio (CNR) [SI.…”

“…The recording and readout characteristics of MSR-CAD disks, such as aperture size, wall width, and noise sources, are dependent upon laser power, pulse duration, timing synchronization, and magnetic interaction of multilayers [4]- [6]. In this paper, we shall report experimental and simulated results of pulsed and dc schemes to evaluate the readout characteristics of MSR-CAD disks.…”

“…1. The physical parameters [3], [6], [7] of the thin film materials used in this study are listed in Table I. A laser source of 785 nm wavelength, an objective of NA = 0.55, and a disk linear velocity of 6.6 m / s were assumed in the simulation.…”

Pulse–read on erasable thermal phase-change superresolution disks

“…In contrast to the dc read method used for conventional phase-change disk readout, we applied a pulse-read 12,13 method to detect the signal on the EPSR disks. We show the advantages of using pulse-read on the EPSR disks to achieve higher recording density by exploring its feasibility analytically and experimentally.…”

CNR Improvement Using Pulsed-Laser Readout on Magneto-Optical Disks

“…When MSR-CAD disks are spinning at high rpm, DC-laser irradiation produced aperture is not in circular but in tear-drop shape, thus complicating the signal processing for the asymmetric readout signal [1-2,4]. By applying tens-nanosecond pulsed-laser irradiation, a quasi-circular aperture can be created to readout sub-,um sized recording marks with adequate carrier to noise ratio (CNR) [2,4]. In this paper, we report the experimental and simulation on pulsed and conventional DC-readout schemes applied to MSR-CAD MO disks to evaluate their readout characteristics such as CNR, jitter, and timing synchronization.…”