Developing optical interconnection devices for next-generation information processing

The Ishigure Laboratory is developing optical interconnection devices using plastic materials. The aim is to introduce optical communication into computers, where electrical signals are still utilized, in order to achieve next-generation computer systems.

Q. "Inside computers, information processing is performed electronically, so even if optical fibers and communication technologies advance, optical signals cant be introduced into computers. But recently, servers and routers in communication networks are reaching their limits in terms of processing capacity. So were researching technologies for optical interconnections, which will enable electrical connections on boards like this to be replaced with optical ones. "

To replace current electrical connections with optical ones, high-speed, high-density transmission media are necessary. To solve this problem, the Ishigure Lab has fabricated prototype graded-index core optical waveguides from polymer materials, and suggested using them for optical interconnections. Because organic polymers cost little and are easy to process, they enable optical interconnection devices to be manufactured at low cost. Its also been shown that, compared with conventional optical waveguides, these graded-index core polymer waveguides can reduce propagation loss and crosstalk.

Q. "Optical waveguides are used over shorter distances, on boards or cards like this. Our group does R&D on plastic optical waveguides for optical interconnections, and how to use these plastic waveguides for high-speed and high density optical interconnections. Here, high-density means very narrow pitch of waveguide."

In this research, the Ishigure Lab has recently focused on carbon nanotubes, which are nonlinear optical materials. Carbon nanotubes are superior to other materials in various ways, including their strength and electrical and chemical properties. However, theyve been unable to display their performance sufficiently, because the strong agglomeration between particles causes excessive light loss.

In response to these issues, the Ishigure Lab has combined the potential of optical polymers and the characteristics of carbon nanotubes, leading to the possibility of even better optical devices.

Q. "In anticipation of even faster optical signal processing in the future, these carbon nanotubes are also being considered for all optical information processing. Were promoting a part of those research trends by developing nanotube doped plastic materials, to fabricate new optical devices."

Information processing by computers will continue to evolve. The Ishigure Lab would like to contribute, by developing optical interconnections from scratch.

Q. "When we made this kind of devices, we didnt yet know how it would perform. When we actually injected light signals to the waveguides wed made, we were very happy to find that The light really passed through! and Its really bright!. And when we obtained the result that high-speed communication is realized with our devices, which is just what wed expected, were really moved, and I believe such a feeling would be available because we have fabricated the devices from the primary stage with enormous effort."