DESIGN AND ANALYSIS OF PLASMONIC WAVEGUIDES FOR HIGHSPEED OPTICAL MODULATION AND SINGLE MODE OPERATION

Abstract

Plasmonic waveguides show an excellent promise in the design of highly compact small footprint photonic integrated circuit components. Notable among them are the metallic nanowires, which have been explored to a great extent in designing highspeed broadband optical interconnects due to the availability of nanofabrication technology and ease of plasmon excitation. However, it is required to explore other functional nanophotonic devices like modulators, switches, detectors etc. in order to conceptualized the overallminiaturization of optical chips. These devices have not been investigated to the extent the nanophotonic optical interconnects have been studied. In addition to that, most of the graphene incorporated designs of optical modulators suffer from a weak light-graphene interaction, which gives rise to a low extinction ratio and narrow modulation bandwidth along with a large device footprint. Moreover, the single mode operability of an arbitrary SPP mode in plasmonic interconnects could serve as single mode fibers of nanophotonic circuits, which has not been explored yet.For addressing these issues, we have proposed several coupled nanowire-based plasmonic waveguides, which offer a highly confined supermode with improved propagation characteristics. The supermode has been exploited here to address the challenges of the conventional graphene-based optical modulators–low extinction ratio, large device footprint, and narrow modulation bandwidth. The coupled nanowire-based designs demonstrate a noteworthy improvement of modulation performance over the conventional plasmonic modulators even with the anisotropic graphene layers. Apart from that the design of the plasmonic modulator have been modified to propose a broadband single mode SPP waveguide, which shows its high promise in broadband single mode operation, design of dipole SPP source, and highly compact photonic integration. All the results are obtained usingthe E-field based full-vectorial finite element simulations.