Nanooptical characteristics of double-sided grating structure with nanoslit aperture for heat assisted magnetic recording

In heat assisted magnetic recording (HAMR) technology, it is required that the light delivery system has both high near-field optical intensity with small spot size and easy integration with a magnetic head. To satisfy these requirements, a grating structure combined with a nanoslit aperture is proposed and designed using a finite differential time domain (FDTD) simulation. Since the surface plasmon polaritons are excited by the grating structure, and the near-field transmitted light is confined locally near the lower grating structure in the exit plane, the near-field optical intensity of light that penetrated through the nanoslit aperture of the asymmetric double-sided grating structure increased 10-fold compared with that of light penetrating through the nanoslit aperture without the grating structure. In addition, the spot size obtained using this proposed grating structure is reduced to 36% of that obtained using nanoslit aperture without the grating structure.