Thermally Assisted Magnetic Recording Head using Focusing Waveguide

Abstract

We have proposed a novel thermally assisted magnetic recording head for future hard disk drives using a “Focusing Waveguide” (waveguide-type spot size converter). The Focusing Waveguide, which has a small size enough to be integrated into a flying slider, can focus the spot diameter of incident light less than one tenth while the light propagate only 200 μm in the waveguide. The focused spot illuminates a plasmon antenna to generate an enhanced near-field spot for heating a very small region of a recording media. We fabricated the Focusing Waveguide and evaluated its focusing properties by means of SNOM measurement method. A measured spot size was 0.37 μm × 0.42 μm (FWHM, Incident spot size = 5 μm). Since a core of the Focusing Waveguide is made of silicon, wavelength of the incident light was set to be 1310 nm. In order to examine the plasmon enhancement of the gold plasmon antenna at this wavelength, FDTD simulations and SNOM measurement was conducted. The results have shown that the combination of a gold plasmon antenna and the silicon substrate gives the fairly good plasmon enhancement at the wavelength of 1310 nm.