Comparative study of optical near-field transducers for heat-assisted magnetic recording

Heat-assisted magnetic recording (HAMR), widely considered to be the next generation technology for high-density data storage devices, uses a tiny plasmonic antenna called a near-field transducer (NFT) to focus light down to a subdiffraction volume. This results in a temporary and local rise in temperature of the recording medium thereby reducing its coercivity, allowing the external magnetic field to write data bits in the medium. The performance of any HAMR system strongly depends on the design of the NFT. The optical performance in terms of the optical coupling efficiency and the spot size for several different NFT designs, including the triangle antenna, E antenna, bowtie aperture, lollipop antenna, and C-aperture, are considered. Also, the corresponding temperature rise in the recording medium and the NFT is calculated and several figures of merit based on the temperature profile are compared for the different designs. This work gives a comparison of the relative performances of different types of NFT and can be a basis for choosing a suitable design for HAMR applications. © 2017 Society of Photo-Optical Instrumentation Engineers (SPIE) [DOI: 10.1117/1.OE.56.12.121906]