Modulator magic

Supercomputers consists of thousands of processors connected by miles of copper wires could one day fit into a laptop pc following the development by IBM of a more efficient silicon Mach-Zendler electrooptic modulator. The device is said to be at least 100 times smaller than previously demonstrated modulators of its kind and IBM believes in could allow complete optical routing networks to be integrated on one chip. “Work is underway within IBM and in the industry to pack many more computing cores on a single chip,” said Dr TC Chen, IBM Research’s vice president, Science and Technology. “What we have done is a significant step toward building a vastly smaller and more power efficient way to connect those cores, in a way that nobody has done before.” In the approach, an input laser beam is delivered to the optical modulator, which acts as a very fast ‘shutter’ – controlling whether the input laser is blocked or transmitted to the output waveguide. When a digital electrical pulse arrives from a computer core, a short pulse of light is allowed to pass through at the optical output. In this way, the device ‘modulates’ the intensity of the input laser beam and the modulator converts a stream of digital bits into light pulses.