Optical synchronous clock distribution network and high-speed signal

Abstract

An optical waveguide H-tree design is provided for global clock distribution on multichip modules (MCM) which has nearly zero clock skew and is useful for a distributed computer system environment. The optical waveguide H-tree design utilizes channel waveguides, curved sections and directional couplers formed using silica glass and silicon oxynitride (SiON) channel waveguide technologies. A hybrid combination of both SiON and silica glass is disclosed which has the advantages of each. The achievable clock speed is limited by the laser diode source and photodiode receiver at each chip module, and not by the optical waveguide distribution network. The high-speed optical waveguide can be configured to transmit clock signals, or for use as a multi-wavelength communication network that communicates signals to various integrated circuits (ICs) mounted on the multichip module. This is achieved using multiple laser diodes having different output wavelengths and directing their outputs into an optical multiplexer. At the receiving points on the ICs, optical demultiplexers filter the optical signals into individual output signals. In addition, multiple 'stacked' optical waveguides can be constructed on the MCM to transmit multiple optical signals, and such optical signals can be either of single wavelength or multiple wavelength type.