In addition to the development of longer-distance and higher-speed VCSELs, there is a possibility that in the long term, polymer waveguide material embedded in electronics could also help to extend the life of multimode fiber in data centers. Yet right now, the technology appears to be reminiscent of the use of silicon photonics with active components, but without the hype. As with SI photonics, the concept of these types of waveguides has been discussed for many years with the problem of loss being a major concern, and right now, the vast majority of dialog on the latter can be found almost exclusively in engineering papers and patent applications.
An exception has been Dow Corning, which has for a while been making somewhat of a marketing push, such as at trade shows with its short-reach interconnects utilizing “low loss,” silicone-based polymer waveguides. Back in early 2013, both Dow and IBM announced their joint research development efforts on these photonics.
Assuming widespread market acceptance of this approach, there would be a couple of intriguing advantages. By integrating optics onto an electronics board with polymers, the density of the overall packaging would increase and the need for thick cables would be reduced. In addition, there would be the enablement of couplers, which would allow data centers to stay with multimode fiber while not just restricting them to point-to-point, short-distance fiber.
Projecting just when polymer waveguides would potentially make an impact on the market is difficult, but it would be heavily dependent on the applications. While there seems to be some optimism that they can play a role in supporting complementary solutions including TOSAs and optical taps, we are aware of a company that tested such a solution for optical splitters in 2014, and the determination was that the loss was still a little bit higher.
It should be noted that a EU-funded, three-year project, which began at the beginning of 2014, Revolutionary Advances in Photonics Integration Being Applied for Optical Communication (RAPIDO), is devoted to high-performance computing systems. IBM Research GmbH in Switzerland, the major end-user in the endeavor, is developing polymer waveguides for intra-rack transmission – albeit for singlemode fiber.
[written by Mark Lutkowitz]
(For our view on IBM's take on silicon photonics, please click here.)