| 摘要 |
A microoptical method and a corresponding sensor for detecting chemical substances in a sample. The sample is brought into contact with the waveguiding layer of a planar optical waveguide. Coherent light is coupled into the waveguiding layer, propagates therein as a guided wave, and the latter is decoupled from the waveguiding layer. Both, coupling and decoupling of the light wave guided in the planar waveguide are effected by means of a mul ti- diffractive grating situated in the plane of the layer, i.e. a grating structure comprising two or more fundamental frequency components for in-coupling and out-coupling, respectively. The multi-diffractive grating coupler result s in a directional separation of decoupled light from reflected, transmitted and directly diffracted sub-beams, respectively. This makes possible a backgroun d- free detection of guided light decoupled from the waveguiding layer, althoug h the regions on the waveguiding layer in which coupling and decoupling of the guided light wave take place overlap in part.
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