Nanoimprint Fabrication of Slot Waveguides

A nanoimprint mold for optical waveguide applications was fabricated by combining photolithography and focused ion beam (FIB) milling. The feasibility of the proposed method was demonstrated by imprinting 15-mm-long Y-branch waveguides, which had nanoscale slots embedded in one arm. Structural analysis of the FIB milled region showed surface roughness values below 2.5 nm. Characterization of the fabricated waveguides proved that 44% of the optical power was transmitted through the slot-embedded waveguide arm. Operation of slot waveguide was demonstrated at a wavelength of 1305 nm using Young interferometer devices.