Design of T-shaped nanophotonic wire waveguide for optical interconnection in H-tree network.

Nanophotonic wire waveguides play an important role for the realization of highly dense integrated photonic circuits. The miniaturization of optoelectronic devices and realization of ultra-small integrated circuits strongly demand compact waveguide branches. T-shaped versions of nanophotonic wires are the first stage of both power splitting and optical-interconnection systems based on guided-wave optics; however, the acute transitions at the waveguide junctions typically induce huge bending losses in terms of radiated modes. Both 2D and 3D finite-difference time-domain methods are employed to monitor the efficient light propagation. By introducing appropriate combinations of dielectric posts around the dielectric-waveguide junctions within the 4.096μm×4.096μm region, we are able to reduce the bending losses dramatically and increase the transmission efficiency from low values of 18% in the absence of the dielectric posts to approximately 49% and 43% in 2D and 3D cases, respectively. These findings may lead to the implementation of such T-junctions in near-future high-density integrated photonics to deliver optical-clock signals via H-tree network.