Automated testing methodologies for low cost, parallel optical bus components

Abstract

The need for low cost, parallel optical bus modules that are competitively priced with existing copper bus technology necessarily implies a need for low cost testing methodologies. The testing of parallel optical bus components however poses unique challenges for the automated test environment. Optical bus components are high data rate, mixed signal, parallel devices that are still in the early stages of development. There are basically two approaches one can take to address these issues but each approach has its own strength and limitations. The first is mixed-signal evaluation of isolated components; the second is (digital) functional testing of links. This paper describes the development and implementation of engineering level testing methodologies, under the sponsorship of ARPA for the OETC program and NIST-ATP for the Jitney program, for detailed characterization of optical bus components and modules. It documents the testing results of over 100,000 VCSEL LIV curves and extracted parametric data acquired at multiple operating temperatures; over 14,000 laser driver channels evaluated for performance at the wafer level; more than 20,000 OptoElectronic Integrated Circuits (OEIC) receivers measured for optical input sensitivity and output electrical parameters; as well as optical bus transmitter and receiver module characterization. This paper also presents a framework for the transition from the high cost engineering testing in a technology development phase to the low cost manufacturing testing needed for the successful introduction of low cost optical bus products into the market place.