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All-optical high-speed signal processing with silicon–organic hybrid slot waveguides


Integrated optical circuits based on silicon-on-insulator technology are likely to become the mainstay of the photonics industry. Over recent years an impressive range of silicon-on-insulator devices has been realized, including waveguides1,2, filters3,4 and photonic-crystal devices5. However, silicon-based all-optical switching is still challenging owing to the slow dynamics of two-photon generated free carriers. Here we show that silicon–organic hybrid integration overcomes such intrinsic limitations by combining the best of two worlds, using mature CMOS processing to fabricate the waveguide, and molecular beam deposition to cover it with organic molecules that efficiently mediate all-optical interaction without introducing significant absorption. We fabricate a 4-mm-long silicon–organic hybrid waveguide with a record nonlinearity coefficient of γ ≈ 1 × 105 W−1 km−1 and perform all-optical demultiplexing of 170.8 Gb s−1 to 42.7 Gb s−1. This is—to the best of our knowledge—the fastest silicon photonic optical signal processing demonstrated.

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Figure 1: Structure and organic molecule of a silicon–organic hybrid slot waveguide.
Figure 2: Scanning electron microscope (SEM) image of the SOH waveguide and nonlinear waveguide dynamics.
Figure 3: Experimental set-up of the all-optical demultiplexing by four-wave mixing.

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This work was supported in part by the DFG (German Research Foundation) Center for Functional Nanostructures (CFN), by the Initiative of Excellence of the University of Karlsruhe within a Feasibility Study of Young Scientists (FYS), the Karlsruhe School of Optics, and by the European project TRIUMPH (Transparent Ring Interconnection Using Multi-wavelength PHotonic switches, grant IST-027638 STP). We acknowledge support by the European Network of Excellence ePIXnet, including fabrication by ePIXfab (, and by ASML Netherlands B.V., and we acknowledge equipment loan from Siemens Portugal and from Optoelectronics Research Centre (ORC) in Southampton, UK. I.B. and B.E. acknowledge partial support from the Commonwealth of Pennsylvania, Ben Franklin Technology Development Authority. F.D. and T.M. acknowledge support from the ETH research council.

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Correspondence to W. Freude or J. Leuthold.

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Koos, C., Vorreau, P., Vallaitis, T. et al. All-optical high-speed signal processing with silicon–organic hybrid slot waveguides. Nature Photon 3, 216–219 (2009).

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