Yuzuru Tanabe

Grating Polarizing Beam-Splitter Using Polymerized Liquid Crystal

A grating polarizing beam-splitter was developed using a newly synthesized UV curable liquid crystal. The fabricated device shows high diffraction efficiency (+1st order: 35.5%, -1st order: 31.9%) and transmittance (83.8%). The temperature dependence of diffraction efficiency variation was suppressed by about 5% within temperature range from 20 to 80°C because these device parameters become less sensitive to temperature variation as a result of photopolymerization.

Direct modulation of blue radiation from frequency‐doubled AlGaAs laser diode using the electro‐optic effect in a KNbO3 nonlinear crystal

A novel method for modulating frequency‐doubled blue radiation from an AlGaAs laser diode was developed utilizing the electro‐optic effect in a KNbO3 nonlinear crystal. Stable blue radiation was obtained from an external ring resonant cavity containing a KNbO3 crystal. The weakly excited counterpropagating mode in the resonant cavity was re‐injected into the laser diode to establish self‐locking. Nearly 100% intensity modulation was observed when a 3 kV/cm ac electric field was applied parallel to the c axis of the KNbO3 crystal.

Methods of Achieving Compatibility between High-Density Disk and Digital Versatile Disk Using a Bi-aspherical Singlet and a Wavefront Compensation Element

We have suggested methods to achieve read/write compatibility for a high-density (HD) disk of 0.1 mm substrate thickness and digital versatile disk of 0.6 mm substrate thickness by simply adding an optical element. We have confirmed that the polarized holographic optical element (HOE) and polarized phase compensator (PPC) are strong candidates for achieving compatibility.