Browsing by Author "Hwang, WK"

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Carrier-to-noise ratio improvement with pulsed-laser readout on magnetically induced superresolution by center aperture detection disks
(1999-09-01)
Chen, BM
;
Yang, BW
;
Hwang, WK
;
Shieh, TE
;
Shieh, HPD
Magnetically induced superresolution by center aperture detection (MSR-CAD) using pulsed and conventional de schemes were applied to magneto-optical disks to quantitatively evaluate readout performances. By simulation and experiments, it was found that carrier-to-noise ratio (CNR) in the pulsed-laser readout was about 2.5 dB higher than that in the de readout scheme at mark size of 0.45 mu m or shorter, Therefore, pulsed readout is feasible to improve CNR and recording density in MSR-CAD disks.
Exchange coupling coefficient and domain wall mobility of (Dy,Tb)FeCo magneto-optical films
(1997-06-01)
Hwang, WK
;
Wu, TH
;
Shieh, HPD
;
交大名義發表
;
光電工程學系
The magnetic properties and recording characteristics of (Dy,Tb)Fr,Co films are dependent upon the anisotropy dispersion of rare earth constituents and the exchange integral between rare earth and transition metal sub networks. The exchange coupling coefficient lambda and the domain wall mobility mu(eff) are found to be interrelated by both measurements and calculations. The higher the lambda or the lower the mu(eff), the higher bias field that is required for magneto-optical recording. The temperature independent lambda is demonstrated to be an important parameter in the assessment of magnetic properties and recording characteristics of sperimagnetic films. (C) 1997 American Institute of Physics.
Interface wall energy in exchange-coupled magneto-optical recording films
(1997-05-01)
Hwang, WK
;
Liu, JR
;
Shieh, HPD
;
交大名義發表
;
光電工程學系
Exchange-coupled double-layered (ECDL) films were adopted to increase density of magnetically induced superresolution (MSR) media by using center aperture detection scheme, and to improve sensitivity of switching field simultaneously. A carrier to noise ratio of 40 dB was obtained at 0.5 mu m recording marks produced by a switching field of 75 Oe. Temperature dependence of interface wall energy affects recording/playback characteristics of ECDL MSR disks considerably.
Interface wall energy in exchange-coupled magneto-optical recording films
(1997-05-01)
Hwang, WK
;
Liu, JR
;
Shieh, HPD
;
光電工程研究所
;
Institute of EO Enginerring
Exchange-coupled double-layered (ECDL) films were adopted to increase density of magnetically induced superresolution (MSR) media by using center aperture detection scheme, and to improve sensitivity of switching field simultaneously. A carrier to noise ratio of 40 dB was obtained at 0.5 mu m recording marks produced by a switching field of 75 Oe. Temperature dependence of interface wall energy affects recording/playback characteristics of ECDL MSR disks considerably.
Magnetic exchange coupling in (Dy,Tb)FeCo magneto-optical recording films
(1997-03-15)
Hwang, WK
;
Shieh, HPD
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
The required bias field of a sperimagnetic film is governed by a finite exchange coupling coefficient (lambda) mainly determined by the subnetwork coupling. From the study of a series of (Dy,Tb)FeCo films at compensation composition it is found that lambda is mainly determined by the concentration of the rare earth components. Moreover, the exchange integral between rare earth and transition metal subnetworks can be derived from lambda so that the number of uncertain parameters for mean held modeling is reduced. Accordingly, the bias field required for magneto-optical recording is mainly proportional to lambda that can be obtained quantitatively from either measurement and/or mean field modeling. (C) 1997 American Institute of Physics.
Magnetic exchange coupling in (Dy,Tb)FeCo magneto-optical recording films
(1997-03-15)
Hwang, WK
;
Shieh, HPD
;
光電工程研究所
;
Institute of EO Enginerring
The required bias field of a sperimagnetic film is governed by a finite exchange coupling coefficient (lambda) mainly determined by the subnetwork coupling. From the study of a series of (Dy,Tb)FeCo films at compensation composition it is found that lambda is mainly determined by the concentration of the rare earth components. Moreover, the exchange integral between rare earth and transition metal subnetworks can be derived from lambda so that the number of uncertain parameters for mean held modeling is reduced. Accordingly, the bias field required for magneto-optical recording is mainly proportional to lambda that can be obtained quantitatively from either measurement and/or mean field modeling. (C) 1997 American Institute of Physics.
Readout scheme by pulsed irradiation center aperture detection on magnetically induced super resolution magnetooptical disks
(1996-01-01)
Yang, BW
;
Hwang, WK
;
Shieh, HPD
;
交大名義發表
;
光電工程學系
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 quasicircular temperature profile, thereby yielding a quasi-circular sub-mu m aperture to effectively derive a readout signal from sub-mu 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.