All-dielectric light concentrator to subwavelength volume
Concentration of light into a nanospot is essential for the heat assisted magnetic recording, biomedical imaging, sensing, and nanolasing. We propose a novel all-dielectric optical field concentrator, which focuses the light, pumped through the waveguide, into a hot nanospot, which is much smaller than the wavelength. The dissipative loss, which is characteristic to a plasmonic nanoantenna, is absent in the dielectric concentrator. Therefore, the detrimental thermal effects almost vanish, which gives an opportunity to use the concentrator for the heat-assisted magnetic recording. The electric field is much enhanced in the proposed new device at the vertex of the dielectric beak, which is attached to the dielectric resonator. The resonator in turn is pumped through the special waveguide. The electric field enhancement and concentration is achieved by longitudinal polarization of the beak vertex, which is exposed to em electric field generated by the pumped resonator. The spatial scale of the hot spot, where the field concentrates, is determined by the curvature of the vertex and can be of few nanometers. We take as a design concept the cylindrical waveguide, the spherical resonator, and the elliptic beak. The rectangular, 2.5-dimensional design of the light concentrator is also considered.