25G/40G VCSELs Driving Short-reach Optical Interconnects

By Lisa Huff

Just a few years ago, laser designers were struggling with stability of their 10G VCSELs. But now, at least one, VI Systems GmbH, claims it will have production-ready 40G VCSELs within the next few years. The German start-up has developed two products it believes will take VCSELs beyond 10G applications - a directly-modulated (DM) device and an electro-optic modulated (EOM) DBR VCSEL. Both are short-wavelength (850nm) lasers.

In a recent press release, VI Systems explains that it “developed the VCSEL products at a wavelength of 850 nm along with a range of extremely fast integrated circuits based on the SiGe BiCMOS (silicon-germanium bipolar junction transistors in complementary metal-oxide-semiconductor) technology. The company uses a patent pending micro-assembly platform for the integration of the opto-electrical components and for alignment to a standard high performance multi-mode glass-based fiber.” The start-up has been presenting data supporting its claims of highly stable devices for more than a year now. It gets there by changing the laser active region material and structure to InAs quantum dot (QD).

Not only is VI Systems working on innovative laser structures, it has also developed new electro-optic integration methods to further reduce the cost of these devices.

I’ve noted in previous posts how VCSELs are the key to low-cost optical networks in the data center. These new VCSELs and packaging methods would bring an even more cost-effective “serial” solution for 40/100G. They could also be used for very short-reach optical connections like for chip-to-chip, on-board or board-to-board. Perhaps these inventive products will rival Avago’s MicroPOD and Luxtera’s OptoPHY (also in previous posts). Based on the presentations that VI Systems has released, it sure appears that its management completely understand the needs of both the data center and optical interconnect markets so could very well give incumbents in the industry some competition.