Masaki Itoh

Analysis of Scattering Light from Magnetic Material with Land/Groove by Three-Dimensional Boundary Element Method

A calculation method with three-dimensional Boundary Element Method (BEM) has been developed for analyzing scattering light from a magnetic material, in order to determine the contribution of land/groove shapes and incident beam polarization to Kerr rotation. A product of scattering beam intensity and the Kerr rotation angle (R.c k ) has been calculated in the case that 680 nm wavelength Gaussian beam is focused on 680 nm or 1360 nm width land/groove, which has 85 nm depth or height. The land or groove shapes have been varied from rectangular shapes to V-shapes. Regardless of the land/groove shapes, the R.θ k of lands is larger than that of grooves in TM-polarization and smaller in TE-polarization. The results in verification experiments well met the calculated ones, i.e., the carrier level of lands is higher than that of grooves in almost the entire range of recording frequency for TM-polarization light, and it is lower for TE-polarization.

Low Loss 1–2 GHz SAW Filters with Submicron Finger Period Electrodes

Low loss GHz SAW filters with submicron finger-period double electrodes have been developed. One was a 1 µm period 0.9 GHz filter with 5 dB insertion loss and the other a 0.5 µm period 1.9 GHz filter with 7 dB loss, both having three-transducer configurations on a 128° Y-X LiNbO3 substrate. These filters were realized by a new fabrication process, using direct wafer electron beam writing, two step mask transfer from electron resist PMMA to photoresist AZ-1350J and ion beam etching. The insertion loss was lowered mainly by optimizing ion beam etching conditions to decrease acoustic propagation losses due to electrode edge geometries, ion etched surface damages and electrode film absorption.

Compact magneto-optical disk head integrated with chip elements

A compact magneto-optical disk head, integrated with chip elements and optical parts, using a hybrid assembly technique, has been developed. Optics and beam splitter characteristics were optimized so as to realize both compact size and sufficient read out characteristics. More than 46 dB C/N ratio and stable operation were achieved, while simple optics and an easy assembly method were used.

New Organic Dye Medium For Ablative Optical Recording

An organic dye medium has been developed for diode-laser high-density recording. The new medium, having a single layer structure, can be recorded and played back by a laser diode through a substrate. It provides 54 dB signal to noise ratio in a 30KHz bandwidth at 2.5MHz carrier frequency. The medium shows excellent properties for long-term stability.

Magnetic Properties and Read/Write Characteristics of Exchange-Coupled Double-Layered Magnetooptical Media Using GdFeCo/TbFeTi Film

We have developed a 200 mm magnetooptical disc using an exchange-coupled GdFeCo/TbFeTi layer and a heat-sink reflective layer of AlTi. Magnetic properties were measured and reported. It was confirmed that this disc had high writing sensitivity suitable for a speed of more than 3600 rpm, high carrier-to-noise ratio, high reflectance and interchangeability under the condition of a high data density of 0.46 µm/bit.