title: Simple interferometer for evanescent field refractive index sensing as a feasibility study for an immunosensor.
abstract: We describe a fiber optic interferometric refractive index sensor to illustrate that, by using the evanescent field of an optical waveguide, a potentially very sensitive determination of changes in the refractive index on the waveguide surface can be obtained. These changes can, e.g., be the result of immunoreactions. We used a Mach-Zehnder interferometer configuration with a flow-through cuvette in one arm with a decladded multimode glass fiber of 0.6-mm diameter and 2-cm interaction length. The obtained resolution in measuring refractive index changes is 1 x 10-(3). We also developed the theory describing the sensitivity of this sensor using the modal and the geometrical ray description.
authors.forename: R G
authors.initials: RG
authors.lastname: Heideman
authors.forename: R P
authors.initials: RP
authors.lastname: Kooyman
authors.forename: J
authors.initials: J
authors.lastname: Greve
authors.forename: B S
authors.initials: BS
authors.lastname: Altenburg