The IBM engineers have drilled 48 holes through the back of a standard 90-nm CMOS chip to allow access for 24 receiver and 24 transmitter channels. The transceiver IC includes 24 industry-standard vertical cavity surface emitting lasers tuned to operate at a wavelength of 850-nm and 24 photodiodes that are flip-chip attached to the optochip. The optical vias are drilled as a post processing step on completed CMOS wafers. The holey optochips are designed for direct coupling to a 48-channel multimode fiber array through a microlens optical system that can be assembled with conventional packaging tools.
The transceiver consumes less than five watts making the bit transmission energy efficiency among the best ever reported, IBM said.
Parallel optics is a fiber technology that is primarily targeted at short-reach, high data rate communications of less than 150 meters. The technology is expected to find use in cloud computing next-generation data centers
"Reaching the one trillion bit per second mark with the holey optochip marks IBM's latest milestone to develop chip-scale transceivers that can handle the volume of traffic in the era of big data," said IBM Researcher Clint Schow, in a statement. "We aim to improve on the technology for commercialization in the next decade with the collaboration of manufacturing partners," he added.
Photomicrograph of the back of the IBM holey optochip with lasers and photodectors visible through substrate holes.