Compact Photonic Devices in Low Index Contrast Waveguides

Abstract

Much attention has been focused on reducing the size of waveguide components to enable higher levels of integration in planar lightwave circuits (PLCs). Waveguide bends and splitters are particularly critical elements that heavily influence overall component size. An obvious approach to shrink the size of such components is to use waveguides with high refractive index contrast that permit a minimum bend radius in the range of microns to 10’s of microns. However, most commercially available PLCs are based on very low loss silica waveguides, which have a low refractive index as well as low refractive index contrast between the core and clad. Moreover, polymer waveguides, which typically have similar low refractive index and low index contrast, continue to receive attention as an attractive candidate for PLCs. We have developed an approach that permits the realization of small bends and beamsplitters in low index and low index contrast materials systems such as silica and polymers. Our approach is based on etched air trenches with vertical planar interfaces.