A Novel Design of Capacitive Plasmonic Near Field Transducer

A near field transducer (NFT) is a key photonics component in heat assisted magnetic recording (HAMR) for the localized heating of the magnetic medium. In this work, we present a novel NFT design through capacitive coupling. In our design, tapered metal bars separated by thin dielectric materials with gap distance G are used to create the plasmonic resonance and focus the electromagnetic field. The design is motivated by the intention to improve thermal stability, which can be achieved through segmentation using thermally stable dielectric material between the plasmonic metal bars. Using COMSOL Multiphysics software, the performance of this capacitive-coupled NFT is systematically modeled. It is shown that the electromagnetic field could gradually be focused through the tapering towards the air bearing surface (ABS). In addition, the focusing effect could be enhanced with a smaller NFT peg size at the resonant wavelength. The material selection for the NFT tip material will be discussed to further address the thermal stability of the device. In conclusion, this capacitive-coupled NFT with dielectric separation gaps and tapering yields an enhanced |E| field intensity at the tip with the potential for an enhanced material thermal stability. Such a design can also exhibit applications in other energy delivery systems as well as plasmonic waveguides and sensors.