Hybrid plasmonic waveguide with centimeter-scale propagation length for nanoscale optical confinement

A centimeter-scale hybrid plasmonic waveguide (HPW) structure based on a grating is proposed at telecom wavelengths. The high-contrast grating is formed by Si and air placed in an air slot created in the high-index region for attaining nanoscale optical confinement. High-contrast gratings help enhance the propagation length up to 3.6 cm with very low loss of 0.11  dB/mm. Further, the extremely large figure of merit 1,129,623 (>10⁷) with nanoscale confinement of 0.00081/μm² is introduced. In the present work, finite-element-method-based COMSOL Multiphysics software was applied to simulate and analyze the properties of a HPW structure. The proposed HPW device can be used for next-generation applications of nanolasers and modulators.