HIGHLY COMPACT OPTICAL WAVE-GUIDES WITH A NOVEL PEDESTAL GEOMETRY

A structure with a large refractive index ratio between waveguide and cladding materials can be fabricated with low scattering losses by usi ng Ge on GaAs waveguides at 10-mu m wavelengths. We demonstrate two ty pes of ultra-high confinement (UHC) dielectric waveguides using separa te geometries: A ridge and a novel pedestal. Computer simulations usin g a time-domain finite element method and microwave-scale experiments are performed on both waveguide types. We show a waveguide thickness o f 0.18 of the free-space wavelength or greater guide well-confined sin gle-mode light for both geometries. Numerical and experimental values of the effective index agree to better than 0.5%.