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

Abstract

Near-field optics is one of super-resolution techniques for future data storage system. We have already proposed a nearfield 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.

Sub-100-nm ROM pattern readout using a triangular protruded aperture mounted optical head slider

“…By controlling the polarization direction of the incident light, they demonstrated the possibility of a 100-nm spatial resolution despite the use of a 190-nm-size aperture. The effectiveness of a triangular aperture in practical optical head slider construction has been investigated by using a contact head slider having three contact pads and a triangular aperture on the slider's surface (Hirata et al 2005b;. Avoiding the difficulties involved regarding both the long term reliability and the stability of an aperture sliding on a metal patterned medium at a higher circumferential velocity, they moved the patterned medium by means of a linear piezo-electric, combined-stage actuator, limiting its stroke to within several micrometers and a sliding velocity of 60 nm/s.…”