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Optical waveguide device

  • US 5,436,991 A
  • Filed: 08/02/1994
  • Issued: 07/25/1995
  • Est. Priority Date: 01/17/1992
  • Status: Expired due to Term
First Claim
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1. An optical waveguide device including a diffraction grating means formed on an optical waveguide which is laid over a transparent substrate and the diffraction grating means being coated with a cladding layer, whereinthe optical waveguide, the cladding layer, and the diffraction grating means are arranged in such a manner to define diffracting means for causing a minus first-order wave, where -mλ

  • /N-nc <

    Λ

    , to be diffracted only toward the substrate, while other waves of higher order, which are larger in absolute value than that of the first-order wave, where -mλ

    /(N+nc)<

    Λ

    <

    -mλ

    /(N-nc), are diffracted both toward the substrate and toward the cladding layer, andsaid diffracting means causing at least one of the higher order waves, which is first diffracted toward the cladding layer and is subsequently reflected back to the substrate from the boundary of a cladding layer which is furthest from the substrate, to weaken the other diffracted wave of the same order that is initially diffracted to the substrate whereinm is an integer representing the order of the wave;

    N is the effective refractive index of the waveguide;

    Λ

    is the pitch of the grating;

    λ

    is the wavelength of the light, andnc is the refractive index of the cladding layer.

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