In a paper (Ultra-compact, low RF power, 10 Gb/s silicon Mach-Zehnder modulator) published in the Optics Express journal, IBM researchers detailed a significant milestone in the quest to send information between multiple cores (“brains”) on a chip using pulses of light through silicon, instead of electrical signals on wires. With this new technology, supercomputers could one day be the size of a laptop. In addition, this laptop supercomputer would expend the energy of just one light bulb.
The breakthrough — known in the industry as a silicon Mach-Zehnder electro-optic modulator — performs the function of converting electrical signals into pulses of light. The IBM modulator is 100 to 1,000 times smaller in size compared to previously demonstrated modulators of its kind, paving the way for many such devices and eventually complete optical routing networks to be integrated onto a single chip. This could significantly reduce cost, energy and heat while increasing communications bandwidth between the cores more than a hundred times over wired chips.
The new technology will enable a power-efficient method to connect hundreds or thousands of cores together on a tiny chip by eliminating the wires required to connect them. Using light instead of wires to send information between the cores can be 100 times faster and use 10 times less power than wires.
IBM’s optical modulator performs the function of converting a digital electrical signal carried on a wire, into a series of light pulses, carried on a silicon nanophotonic waveguide. First, an input laser beam is delivered to the optical modulator, which acts as a very fast “shutter” which controls whether the input laser is blocked or transmitted to the output waveguide. When a digital electrical pulse arrives from a computer core to the modulator, 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 (“1″s and “0″s) from electrical signals into light pulses.
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More info: Ultra-compact, low RF power, 10 Gb/s silicon Mach-Zehnder modulator (pdf)