Patent ID: 7751668

Claim:
A method for the micro structuring of an optical waveguide to produce an optical waveguide having a first cross-sectional region with a first refractive index, a second cross-sectional region with a second refractive index, a protective buffer, and a boundary region in the transition from the first to the second cross-sectional region, wherein said first cross-sectional region is composed of undoped silica, wherein at least one defined portion of the boundary region is provided with a modification of at least one optical property of the optical waveguide, said modification being a non-periodic distribution, formed by a defined portion of the boundary region defining at least one of (i) microdamage, and (ii) a surface defined by the removal of material from the defined portion, comprising the steps of: providing an optical waveguide comprising a first cross-sectional region having a first refractive index, a second cross-sectional area having a second refractive index, a protective buffer, and a boundary region in the transition from the first to the second cross-sectional area, exposing the optical waveguide through its protective buffer to laser radiation in the form of at least an ultra-short single pulse or a sequence of ultra-short pulses with a defined energy input; at least one of microdamaging and removing the material from the defined portion of the boundary region with said laser radiation: and modifying at least one optical property of the optical waveguide at one said defined portion at least of the boundary region as a result of the step of exposing the optical waveguide to laser radiation, without removing said waveguide's protective buffer.