Atto-joule All-optical Switch ~Putting a Photonic Network into a Chip

Technological fields
Cutting-edge Technologies
  • Nanophotonics
  • Photonic integrated circuit
  • Photonic crystal
Laboratory organization
NTT Basic Research Laboratories, NTT Photonics Laboratories

Download PDF (357KB)


Energy consumption and heat generation are becoming problematic issues in ICT, and it is expected that the introduction of photonic network technology into an information processing chip will help to alleviate them. Conventional photonic devices are too large and consume too much energy, and thus it is difficult to integrate many photonic devices in a chip at present. NTT Laboratories have built ultra-small all-optical switches that consumes an extremely small amount of energy, by employing a photonic crystal, which is an artificial dielectric structure with a periodic refractive index made by state-of-the-art nano-fabrication technology. We have demonstrated all-optical switching with a consumption energy of only 440 atto*1 joule, a record-low value.


  • Photonic crystal that strongly confine light within a wavelength-sized volume.
  • The all-optical switch with an ultrasmall photonic crystal nanocavity (0.02 Ám3).
  • Highly integratable and ultrasmall device with ultralow energy consumption.
  • All-optical switching of light signals by using a 440-atto joule control light pulse (less than 1/100th the energy of the previous record, Fig. 1).
  • Alleviates trade-off between processing speed and energy consumption (Fig. 2).
  • Capable of extracting pulse from a 40-Gbit/s pulse stream.

Application scenarios

  • Key device for large-scale photonic integration technology. Promising for large-scale photonic integrated circuit.
  • High-speed information processing chips with ultralow energy consumption
  • Useful for implementing large-scale photonic network technology in MPU*2 chips to drastically reduce the energy cost of information processing
  • Integrated chips for routers, datacenters, and mobile terminals
  • *1 atto: 1/1018
  • *2 MPU: Micro Processing Unit