All-Optical Networks: the Last Piece of the Puzzle 36
Esther Schindler writes "An MIT professor explains why "simple" ideas require hard science and how a gemstone might be the key to an optical network. As the story begins: 'For years, the dream of an all-optical network has lain somewhere between Star Wars and a paper cup and a string. Recent successful work on the creation of an optical diode is a virtual case study in both the physics and materials sciences challenges of trying to develop all-optical networks. It is also a significant step towards their final realization.' One answer may be... garnet. Yes, the January birthstone. 'The material that Ross and others in her field use is a synthetic, lab-grown garnet film. Similar to the natural mineral, often used as a gemstone, it is transparent in the infrared part of the spectrum. This makes synthetic garnet ideal for optical communications systems, which use the near infrared. Unlike natural garnet, it's also magnetic. ... While it works, it's too big and too labor intensive for use as a commercial integrated chip. For that, you need to grow garnet on silicon. The challenge that Ross's group overcame is that garnet doesn't grow on silicon.'"
Re:Broadband cable? (Score:5, Interesting)
The current paradigm is "electronic switches, optical in between." This bit of R&D is building toward a goal of "optical cables, optical switches, and only translate it at endpoints."
If the optical computer crowd succeeds, then it would be possible to have all-optical networks, to the point of only translating it to any other format for UI purposes.
As for why this is a good thing, there's a difference between the speed of electrons through copper and silicon vs. the speed of light through translucent plastics and crystals. It should also run cooler.
Re:Broadband cable? (Score:5, Interesting)
Copper is faster - which makes sense if you think about it. Light pipes require high impedance because they depend on total internal reflection to keep the light inside the pipe. The higher the impedance, the tighter you can bend the cable without signal loss.
Rule of thumb: vacuum is 3 ns/m, copper is 4 ns/m, optical cables are 5ns/m. (The long-haul cables may be a bit faster as they're made of different materials and use a somewhat different IR wavelength).
Optical-to-copper interfaces are a mess - usually the most noisey and failure-prone part of the network (aside form the end-user endpoint). All optical switching could improve reliability, power consumption, and EM noise considerably.