IBM Uses CMOS Transistor for 10Gbit/s Optical Data Driver

In order to directly modulate laser light sources in card-to-card optical links, IBM has developed an advanced method meant for CMOS transmitter macros usage, informs Electronics Weekly.

As a matter of fact, at the end of last year, IBM announced that it has developed a 10Gbit/s CMOS-driven VCSEL (vertical cavity surface emitting lasers) link that consumes 2.5mW/Gbit/s, or one-tenth of the SiGe equivalent.

"On the link topology there are things that need to be looked at," said Dr Christoph Berger, who leads the work on optical interconnects at IBM's Zurich Research Lab. "One of the things we are actively looking at is if we can drive the VCSELs right out of the CMOS process."

It seems that the new developed technology is capable of making vertical cavity surface emitting lasers (VCSELs) unite in a 5Gbit/s serial connection, as it is meant to reduce power, area, and most of all cost of optical comms, making them, at the same time, to support high-density datacomms applications.

VCSELs can deliver multiple benefits, because they emit approximately 850nm, and, consequently, are used in the manufacturing of acrylate materials utilized to develop optical waveguides in PCBs. But they can also be used on the wafers, generating a significant reduction of production costs.

"For terabit class data flows, for the big machines, you simply have to assume there are hundreds of channels in such systems, because no single device is fast enough for you just to use a few of them," said Berger. "That brings us down to having many, many lasers to operate, and that's the reason we're looking at VCSELs, and not at telecom-class edge emitters. We need arrays."