Optical waveguide sensors having high refractive index sensitivity
AssigneeLuna Innovations Incorporated
InventorsKent A. Murphy, Mark E. Jones
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Abstract
An optical waveguide sensor having high refractive index sensitivity over a range of ambient refractive indices is provided. The sensor comprises a core having at least one long period gating disposed therein. An inner and outer cladding region, each cladding region having an effective refractive index. The total effective refractive index of the inner cladding region and the outer cladding region is approximately equal to but not greater than the effective refractive index of an environmental parameter to be sensed. These optical waveguide sensors are useful for measuring changes in a variety of environmental parameters.
Claims45
An optical waveguide sensor comprising:
- a core having at least one long period grating disposed therein wherein each long period grating has a plurality of index perturbations spaced apart by a periodic distance Λ, wherein the periodic distance is 10 μm≦Λ≦1500 μm;
- an inner cladding region surrounding the core and comprising a plurality of spaced apart first cladding features disposed within a first cladding material, wherein the inner cladding region has an effective refractive index;
- an outer cladding region surrounding the inner cladding region wherein the outer cladding region comprises a plurality of spaced apart second cladding features disposed within a second cladding material, wherein the outer cladding region has an effective refractive index;
- and
- wherein the total effective refractive index of the inner cladding region and the outer cladding region is approximately equal to but not greater than the effective refractive index of an environmental parameter to be sensed.
A process for measuring changes in an environmental parameter, the process comprising the steps of:
- a) providing an optical waveguide sensor comprising:
- a core having at least one long period grating disposed therein wherein each long period grating has a plurality of index perturbations spaced apart by a periodic distance Λ, wherein the periodic distance is 10 μm≦Λ≦1500 μm;
- an inner cladding region surrounding the core and comprising a plurality of spaced apart first cladding features disposed within a first cladding material, wherein the inner cladding region has an effective refractive index;
- an outer cladding region surrounding the inner cladding region wherein the outer cladding region comprises a plurality of spaced apart second cladding features disposed within a second cladding material, wherein the outer cladding region has an effective refractive index;
- and
- wherein the total effective refractive index of the inner cladding region and the outer cladding region is approximately equal to but not greater than the effective refractive index of an environmental parameter to be sensed;
- b) exposing the optical waveguide sensor to the environmental parameter;
- and
- c) measuring a change in the long period grating coupling conditions.
Dependencies are inferred from the claim text.