Near infrared optical interference filters with improved transmission

  • US 9,989,684 B2
  • Filed: 01/22/2016
  • Issued: 06/05/2018
  • Est. Priority Date: 01/23/2015
  • Status: Active Grant
First Claim
Patent Images

1. An optical filter comprising:

  • a transparent substrate;

    an interference filter comprising a layers stack comprising a plurality of layers of at least;

    layers of amorphous hydrogenated silicon; and

    layers of one or more dielectric materials having a refractive index lower than the refractive index of the amorphous hydrogenated silicon wherein the layers of one or more dielectric materials include layers of a dielectric material having a refractive index in the range 1.9 to 2.7 inclusive;

    the layers stack including repeating units of two or more layers configured to have a passband with properties defined by the repeating units including at least a passband center wavelength,wherein the layers stack includes a first layers stack on one side of transparent substrate and a second layers stack on the opposite side of the transparent substrate.

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