Patent ID: 7864321

Claim:
An evanescent wave multimode optical waveguide sensor for measuring at least one of a chemical species and a physical parameter, the sensor comprising: an optical waveguide having an optical waveguide core with a core refractive index and a cladding, surrounding said core, with a cladding refractive index, for guiding light to be propagated, said optical waveguide having: a sensing portion with a cladding refractive index lower than said core refractive index such that an evanescent wave of said light propagates in said cladding, said cladding comprising a chromoionophore providing an optical absorption varying as a function of said at least one of a chemical species and a physical parameter, said evanescent wave to be at least partially absorbed by said cladding due to said optical absorption, said sensing portion further being provided with mode coupling means having a mode coupling length which is substantially shorter than a length of said sensing portion for causing continuous redistribution between propagation modes, along said sensing portion, of unabsorbed light power of said light as said light propagates; a light source unit connected to said optical waveguide for providing said light to be propagated in said optical waveguide; a detection unit connected to said optical waveguide for detecting said light propagated in said optical waveguide for determining an optical absorbance of said light in said optical waveguide; and a processing unit associated with said detection unit for determining said at least one of a chemical species and a physical parameter from the determined optical absorbance.