Near-field combination apertures for ultra-resolution optical storage

Abstract

This dissertation proposes and demonstrates an innovative technique for ultra-resolution data storage. An original idea that combines two near-field techniques, aperture probes and the solid immersion lens (SIL), is implemented through modeling, fabrication, testing, phase-change recording, and writing condition studies. In the modeling, a theory for illumination and signal detection is presented. The power transmission for different near-field transducers illuminated by a lens is calculated versus NA. In detection, the angular spectrum illustrates advantages of the combination aperture system. In addition, geometrical design considerations are discussed with the modeling. Nearly optimal designs for APSIL and Al aperture + SIL are presented for the illumination wavelength 488 rim. Fabrication techniques are developed for dielectric aperture + SIL, which is called APSIL, and Al aperture + SIL, respectively through modeling geometrical design. Both near-field transducers are tested by edge-scan experiments. Spot size and optical efficiency from the APSIL system are evaluated. APSIL is evaluated for high-density recording on a phase-change medium. Minimum mark size and the modulation transfer function (MTF) are obtained experimentally. Control of writing conditions for an APSIL system are investigated with respect to polarization, axial focus position and transverse beam alignment. Our study shows that the APSIL system achieves much higher optical efficiency than aperture probe systems as well as exhibits better resolution than SIL systems.