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Asi Ag

Oerlikon-Buhrle Holding Ag

Walter Lukosz

Kurt Tiefenthaler

Method and apparatus for selecting detection of changes in samples by

Optical modulation apparatus and measurement method

The optical sensor for the detection of specific substances and refractive index changes in gaseous, liquid, solid and porous samples is composed of integrated optical elements. It consists of a waveguiding film (1) equipped with a diffraction grating (4) and applied onto a substrate (2). For the selective detection of a specific substance contained in the sample (3) a selectively chemisorbing additional layer (5) covers the film (1) at least in the grating region. The sample (3) is applied at least in the grating region either directly onto the waveguiding film (1) or onto the selectively chemisorbing additional layer (5). Chemisorption of the substance, which is contained in the sample (3) and is to be detected, to the selectively chemisorbing additional layer (5) results in a further adlayer (6) coating the waveguiding film (1). The principle of the sensor is as follows: Due to chemisorption of a further adlayer (6) and/or due to a refractive index change of the sample (3) a change in the effective refractive index N of a mode guided in the waveguiding film (1) is effected. For the detection of this change the set-up (1,2,3,4,5) described above is used as grating coupler or Bragg reflector.

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Greifensee, Switzerland

Walter Lukosz