Hybrid Integration Technology of Silicon Optical Waveguide and Electronic Circuit

Due to the proliferation of broadband services in recent years, the volume of information transmitted across the Internet is growing steadily. As a result, data processing capacity of information processing systems are expected to significantly increase. Signal processing in an information processing system can be classified as between equipment, between boards inside the equipment, and between chip and module inside the board. Currently, the use of optical fibers and optical waveguides are on the rise for inter-equipment and in some cases interboard connections. The use of electrical wirings to make high-speed connections between the closely spaced chips in the board poses problems of noise interference, number of wirings and wiring size. Furthermore, judging from the yearly increases in information traffic, electrical wirings will no longer be adequate for interconnections, thereby raising the expectations of optical interconnection technologies. Among the optical interconnection technologies, polymer waveguides and silicon photonics are being studied for use as optical circuit boards. Silicon photonics have extremely high refractive index compared to silicon oxide films or polymer waveguides meaning they have strong confinement of light and are less susceptible to bending loss. Therefore, silicon photonics can be used to form optical circuits with small radius curvatures. The recent advances in silicon process that make nm order processing possible and the availability of high-quality SOI (Silicon on Insulator) substrates have prompted many studies in silicon photonics. In particular, we are researching and developing silicon-wire waveguides. This article will first report on the silicon-wire waveguide design and evaluation of its basic properties. This will be followed by the simulation and evaluation of the wavelength mux/ demux, a vital component in configuring an optical circuit. Finally, the article will report on a sample chip fabricated for a bi-directional optical module.