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Thursday, June 16, 2016

Light Speed Computing

Light-Speed Computer Chips via Carbon Nanotubes

Anne Nasato | June 13, 2016

In the time it takes to snap your fingers, light travels around the world seven times. On a large scale, fiber optics are already used to transmit data via this incredibly fast and energy efficient medium. Now, small-scale applications will be able to transmit ever-increasing amounts of data in the same manner. Computer chips of the near future will reach light-speed thanks to a recent development involving waveguides and carbon nanotubes. Together, they can convert electric signals into clearly defined optical signals.

"PCNBC device with coupled CNT emitter. a, Schematic view of the multilayer device structure consisting of two Au/Cr electrodes (yellow) and a photonic waveguide (purple) that is etched into the Si3N4 layer. Its central part is underetched into the SiO2 layer to a depth of 1.4 µm and PCHs are formed. b, Close-up of the PCNBC illustrating the CNT (black line) in contact wi9th the electrodes on top of the waveguide. c, False-coloured SEM image of the PCNB structure between two electrodes. The cavity centre is precisely aligned with the midpoint between the tips of the two electrodes (tilt angle = 0°). d, SEM image of the cavity centre with the waveguide and two electrodes, bridged by several single-walled CNTs (device 1). The suspended parts of the CNTs are clearly visible, whereas the material contrast on the waveguide top is too low to resolve the CNTs (title angle = 45°)." Source:

<more at; related articles and links: (Carbon nanotubes light up on photonic chips. April 20, 2016) and (Cavity-enhanced light emission from electrically driven carbon nanotubes. Felix Pyatkov, Valentin Fütterling, Svetlana Khasminskaya, Benjamin S. Flavel, Frank Hennrich, Manfred M. Kappes, Ralph Krupke and Wolfram H. P. Pernice. Nature Photonics 10, 420–427 (2016) doi:10.1038/nphoton.2016.70. [Abstract: An important advancement towards optical communication on a chip would be the development of integratable, nanoscale photonic emitters with tailored optical properties. Here we demonstrate the use of carbon nanotubes as electrically driven high-speed emitters in combination with a nanophotonic cavity that allows for exceptionally narrow linewidths. The one-dimensional photonic crystal cavities are shown to spectrally select desired emission wavelengths, enhance intensity and efficiently couple light into the underlying photonic network with high reproducibility. Under pulsed voltage excitation, we realize on-chip modulation rates in the GHz range, compatible with active photonic networks. Because the linewidth of the molecular emitter is determined by the quality factor of the photonic crystal, our approach effectively eliminates linewidth broadening due to temperature, surface interaction and hot-carrier injection.])

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