<title>Performance of polycrystalline silicon waveguide devices for compact on-chip optical interconnection</title>

Abstract

Optical interconnects offer advantages over electrical interconnects in terms of clock skew, crosstalk, and RC delay for ULSI (Ultra Large Scale Integrated-Circuit) silicon technology. Optical interconnects are also applicable in optical communications where compact optical devices are fabricated and incorporated in an on-chip integrated optical system. Polycrystalline silicon (polySi)/SiO2 is an attractive waveguiding system that offers significant advantages in both applications with its compact size and compatibility with multilevel CMOS processing. Based on the process optimization that led to a low-loss polySi material, we have fabricated compact waveguide bends and splitters that were microns in size. To study the modal behavior in bending and splitting, we compared multi-mode and single-mode waveguides that were used in fabricating bends and splitters. Two waveguide cross-section dimensions, 0.5 micron X 0.2 micron and 2 microns X 0.2 microns, were used for single- mode waveguide and multi-mode waveguide, respectively. Micron- sized bending was realized with a low loss of a few dBs. Single-mode bends showed less than 3 dB loss for a bending radius of 3 microns, which was lower than that for multi-mode bends. Two different types of splitters, single-mode Y- splitters and multi-mode Y-splitters were fabricated and characterized in terms of their splitting uniformity. One X four and 1 X 16 optical power distribution systems were built based on different splitting schemes and their output power uniformity was compared. Due to the high dielectric contrast of our polySi/SiO2 waveguide system, the smallest 1 X 16 optical power distribution was realized in an area smaller than 0.0001 cm2.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.