Yunchuan Kong Defense

Yunchuan Kong Defense


Starts at: December 17, 2013 9:30 AM

Ends at: 12:30 PM

Location: HH A306

Details:

Abstract

Heat assisted magnetic recording (HAMR) is a possible solution to further increase hard drive recording density. In a HAMR system, an external light source is employed to locally heat up magnetic media. To achieve a realistic HAMR system, a near-field transducer (NFT) is necessary to focus optical fields down to 10-20 nm in size. Different approaches to excite NFTs have been investigated, including focusing of external light sources and coupling from dielectric waveguides. In this talk, a compact optical path that couples and conditions external optical field into a single mode dielectric waveguide is investigated. Then we demonstrate evanescent coupling between a series of single mode dielectric waveguides and adjacent plasmonic waveguides with relatively large cross section (200 nm X 300 nm). The results demonstrate that coupling in these waveguides can be designed and modeled using mode indices calculated from the eigenmodes of the waveguide cross sections. And coupling strength between these waveguides can be understood by standard coupled mode theory. In next part of the talk, near field measurements of the dielectric waveguides and plasmonic waveguides are presented. A near field scanning optical microscopy system was custom built for this investigation. In addition, fabrication of 3D tapered plasmonic waveguide that can shrink the optical field further down to tens of nanometers are demonstrated. And preliminary results of an alternative approach that excites NFTs by dielectric disks are discussed.