Silicon modulator makes commercial photonics-on-a-chip more likely

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A 40Gbit/s optical modulator has been manufactured using microelectronics production processes, according to European researchers aiming to commercialise silicon photonics.

Photonics on silicon integrated circuits (IC) will mean optical chip-to-chip and rack-to-rack connections that overcome the limitation of existing interfaces. These are the interfaces between traditional optical systems, which are not silicon based, and microelectronics that are IC based. A silicon optical modulator is one element of the new connectivity between microprocessors and photonics.

Manufacturing every element of the photonics chain in Complementary Metal Oxide Semiconductor (CMOS), the silicon upon which ICs are built, is project HELIOS’ goal to overcome the connection limits.  The HELIOS project is a four-year €12m European Union study that ends in 2012. CMOS foundries are the production facilities that manufacture processor and memory chips in the vast numbers that make computing cheap.

The 40Gbit/s optical modulator in CMOS was manufactured by French research institute Leti and designed by the University of Surrey’s silicon photonics group. ‘This result is a major step towards high-bandwidth optical systems on silicon because it makes 40Gb/s modulators viable for commercial applications,’ said University of Surrey professor of silicon photonics, Graham Reed.

The 40Gbit/s CMOS optical modulator has an extinction ratio of 10dB. The extinction ratio represents the difference in the power consumed when there is a signal being sent and when there isn’t. This 10dB ratio is also a significant achievement according to the HELIOS researchers.

In addition to the 40Gb/s modulator, HELIOS' partners are producing 16x10 Gb/s transceivers, photonic QAM-10Gb/s wireless transmission systems and mixed-analogue and digital-transceiver modules for multifunction antennas using CMOS manufacturing processes.