Fabrication and signal readout of near-field optical contact head with a triangular aperture

Near-field optics is one of super-resolution techniques for future data storage system. We have already proposed a near-field optical flying head with a circular aperture. Realizing higher performance aperture, we also have developed a triangular one which has been experimentally evaluated with scanning near-field optical microscope probe. In this paper, we demonstrate readout performance of this novel aperture mounted near-field head introducing polarization control. In order to scan over a media surface at small spacing condition, we fabricate a "contact" type head having contact pads and a polarization maintaining fiber, because this type of an aperture can only effectively function on condition both of extremely small spacing and applying polarized light. The contact pads and the tip are formed by photolithography with hydrofluoric acid (HF) solution. An aluminum film is formed on the tip. The aperture is formed by squeezing the shading film. Measurement of surface configuration by an interferometer shows that the aperture and the contact pads are almost on the same plane within 5 nm deviation. The media consists of a glass substrate, a titanium layer, a carbon protective layer, and a lubricant layer in sequence. Line-and-space (L&S) patterns whose width are 40~200nm are formed on the titanium layer. The contact head approaches the media surface, and then the media is scanned by a piezo stage. The near-field light generate from the triangular aperture is scattered by the L&S pattern and detected by a photomultiplier tube. Signal readout from the 40-nm-wide L&S pattern is demonstrated.

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