Indefatigable Japanese site Egami (translated) spotted another Canon patent. It concerns a 3-layer image sensor that appears to be particularly sensitive to light. No idea where such a sensor could be employed, maybe in a future generation of high-end cameras?

Patent description (machine translated):

• Patent Publication No. 2013-93553
  • Publication date 2013.5.16
  • Filing date 2011.10.4
• Imaging element of three-layer structure
  • Photodiode deep layer (hereinafter, PD) in the charge is diffused into the substrate
  • Thus sensitivity is poor red
• Canon patent
  • I as a photonic crystal of irregular shape, the boundary surface of the PD of red or green,
  • In the periodic structure of uneven spacing, less than twice the 1/4 times or more the wavelength of light, or I shall be two times or less 1/2 times or more
  • Irregular shape has the properties to be spatially-localized or resonant light
    • The incident light is diffracted, it combines with the light of the boundary plane, the resonant
    • Prolonged exists than normal, the light becomes easy to be absorbed by the PD Thus