Various embodiment comprise silicon-on-insulator waveguide designs that simultaneously achieve both high optical confinement, low-loss, and provide for electrical connections. In certain embodiments, high index contrast waveguides comprise a central elongate waveguide portion and a segmented portion comprising a single thin layer of Silicon-On-Insulator that achieves both high optical confinement and minimal insertion loss. Other devices, such as chemical and biological sensors, and optical elements may also be fabricated.