US Patent 7471863 Near-field interaction control element

A near-field interaction control element includes a near-field optical waveguide containing particles formed of a metal, a metal anion or a metal cation with a diameter of 0.5 nm or more and 3 nm or less and a dielectric constant of −2.5 or more and −1.5 or less, an electron injector/discharger injecting or discharging an electron into or from the particles contained in the near-field optical waveguide to vary a dielectric constant of the near-field optical waveguide, a near-field light introducing part introducing near-field light into the near-field optical waveguide, and a near-field light emitting part emitting the near-field light having guided through the near-field optical waveguide.