Stand-off matched index optical waveguide interface

Abstract

The Stand-Off Matched Index optical interface reduces optical reflections thereby increasing return losses that occur when an optical waveguide, including optical fiber, is interfaced to a bulk media of significantly differing refractive index. A small spacer material, or stand-off, is placed between the waveguide and the media. The stand-off is index-matched to the waveguide thereby eliminating reflections from this interface. The length of the stand-off is chosen so the reflections from the stand-off/media interface are weakly coupled back to the waveguide due to diffraction and attenuation losses within the stand-off. This invention can be used in most situations where an optical fiber must be interfaced to a material of significantly different refractive index and is applicable to both multi-mode and single-mode fibers. And, it is generally applicable to any focal plane in an optical system that coincides with a refractive index discontinuity which results in troublesome back reflections. The general Stand-off Matched Index approach is also extendible to waveguides other than fibers, and even unguided light beams, independent of wavelength.

Dependencies are inferred from the claim text.