A novel near field transducer for efficient energy transfer

Interest in the localized surface plasmon resonance (LSPR) of metallic nanoparticles has been piqued by single molecule detection in surface enhanced Raman spectroscopy, scanning optical microscopy with sub-20 nm resolution, particle capture using the optical tweezers effect, and proposed applications in nanolithography and data storage. We have designed a gold near field transducer (NFT) that combines the LSPR effect, the lightning rod effect, and the dual dipole effect. Optical energy that is focused onto the NFT is coupled into a metallic thin film within a spot that is an order of magnitude smaller than the free space wavelength with an efficiency of about 5{\%}. With approximately 40 mW of optical power from a laser diode at a wavelength of 830 nm, data has been recorded at a track width less than 50 nm onto a high coercivity magnetic medium by heating it to its Curie point of 650 K while the medium was rotating at 2700 RPM and the NFT was separated from the medium surface by 15 nm.