Silicon Photonic Wire Waveguides: Fundamentals and Applications

This chapter reviews the fundamental characteristics and basic applications of the silicon photonic wire waveguide. Thanks to its ultra-small geometrical structures and compatibility with the silicon electronics, the silicon photonic wire waveguide provides us with a highly integrated platform for electronic photonic convergence. For the practical achievement of this platform, however, we must search for ways to reduce the propagation loss and coupling loss to external fibers and overcome the polarization dependence. Progress has been made by applying state-of-the-art technologies specially tuned to the fabrication of nanometer structures, and the fundamental propagation performance has already become a practical standard. Some passive devices, such as branches and wavelength filters, and dynamic devices based on the thermo-optic effect or carrier plasma effect have been developed by using silicon photonic wire waveguides. These waveguides also offer an efficient media for nonlinear optical functions, such as wavelength conversion. Although polarization dependence remains a serious obstacle to the practical applications of these waveguides, waveguide-based polarization manipulation devices provide us with effective solutions, such as a polarization diversity system.