PLASMONIC WAVEGUIDE STRUCTURES FOR FUTURE NANOSCALE PHOTONIC INTEGRATED CIRCUITS

Abstract

Emerging telecommunication and data routing applications anticipate a photonic roadmap leading to ultra-compact photonic integrated circuits. Consequently, photonic devices will soon have to meet footprint and efficiency requirements similar to their electronic counterparts calling for extreme capabilities to create, guide, modulate, and detect deep sub-wavelength optical fields. Plasmonics, or metal optics, has emerged as one potential solution for integrated on-chip circuits that can combine both high operational speeds and ultra-compact architectures rivaling electronics in both speed and critical feature sizes. This work describes the current status, challenges, and future directions of the various components required to realize plasmonic integrated circuitry. It delineates the basic concepts of plasmonics technology along with its mathematical approach. The dispersion relation of surface piasmons is depicted. It describes various configurations of plasmonic waveguide structures and presents its characteristic impedance model. Nanostrip waveguides and Surface Plasmon Coplanar Waveguides are two subjects of interest in this work. They are further used to model various components like single and dual band branch line couplers. Band Pass filters are also designed based on plasmonic branch line coupler. A 3dB broadband coupler is designed based on surface plasmon conductor backed coplanar waveguide. It is shown that about 40 Tl-lz bandwidth is achieved over which the coupler has insertion losss in the range of 5 ± 1 dB. This coupler can replace many such narrowband couplers in wireless links and can be used to design compact plasmonic integrated circuits. The advantages, flexibility parameters and limitations of these components are also summarized.