Local Field Enhancement of Mid-Infrared Light in an Integrated Photonic-Plasmonic Structure

We numerically study the local field enhancement of mid-infrared light beating the diffraction limit in an integrated photonic-plasmonic structure. The light is locally transferred from a photonic crystal waveguide to a metallic transmission line on top of it. The transmission line connects the two sections of the photonic crystal waveguide in a passage configuration. The field intensity is locally enhanced in the transmission line passage by a factor larger than 50, with a power transfer efficiency of 33%. This passage structure holds the promise of enabling highly sensitive miniaturized sensing schemes and mid-infrared spectroscopy equipment.