Energy-efficient ultrafast all-optical signal processing may contribute to solving growing bandwidth and energy challenges in optical telecommunications. However, conventional solutions for all-optical data processing rely on nonlinear optical materials with inherent minimum power requirements and trade-offs between bandwidth and speed. In contrast, the coherent interaction of light-with-light in an absorber of nanoscale thickness can facilitate high-contrast modulation of one optical signal with another, ultimately with few-femtosecond response times and at arbitrarily low (even single photon) intensities.
We report here on the first demonstration of a fiberized metamaterial device for all-optical signal processing based upon coherent modulation of absorption. The integrated metadevice is based on a plasmonic metamaterial of nanoscale thickness fabricated on the core area of a single-mode optical fibre, and designed to operate over the 1530 – 1565 nm telecoms wavelength range. We demonstrate signal processing operations analogous to logical NOT, XOR and AND functions at effective rates from tens of kbit/s up to 40 Gbit/s with energy consumption as low as 2.5 fJ/bit, as well as selective absorption and transmission of picosecond pulses and the generation of 1 ps ‘dark pulses’. We anticipate that such metadevices, with THz bandwidth, may provide solutions for quantum information networks as well as orders-of-magnitude improvements in speed and energy consumption over existing nonlinear approaches to all-optical signal processing in coherent information networks.