BALTIMORE - Optical interconnect has generated much interest over the years because of the performance benefits of transmitting signals at the speed of light rather than through copper wire or other solid conductors. A team at The Johns Hopkins University recently announced a breakthrough that moves optical interconnect one step closer to being a feasible production technology.
A key to this development is the use of silicon-on-sapphire instead of standard silicon wafers. With a thin layer of silicon on top of synthetic sapphire, there are new opportunities for transmitting optical signals because the sapphire allows light to pass through it. Microlenses and other optical components that are manufactured as part of the chip steer a laser-generated light beam around the device. When the signal needs to get to another chip, it is coupled into an optical fiber that functionally replaces a wire bond or other more traditional interconnect method. The sapphire substrate also provides the advantage of reduced parasitic capacitance. Because it is an insulator, less power is required to push signals through an interconnect medium.