Microoptical sensor and method
First Claim
1. A microoptical sensor for detecting chemical substances, the sensor comprising:
- a) a solid substrate;
b) a planar waveguide layer located on a surface of the substrate, the planar waveguide layer having an interaction surface for contacting the chemical substances to be detected; and
c) a diffractive grating located proximate to the planar waveguide layer for coupling and decoupling light into and out of the planar waveguide layer, the diffractive grating oomprising at least two superimposed gratings,(i) a first grating having a first fixed fundamental frequency and a first discrete diffraction order, the first grating acting as an input grating coupler for coupling light into the planar waveguide layer at a first discrete coupling angle, the incoupled light interacting with the chemical substances adjacent to the interaction surface and(ii) a second grating having a second fixed fundamental frequency different from the first fundamental frequency and a second discrete diffraction order different from the first diffraction order, the second grating acting as an output grating coupler for coupling light out of the planar waveguide layer at a second discrete coupling angle different from the first coupling angle,the first and second discrete coupling angles causing a detectable directional separation of light coupled into and out of the planar waveguide layer, thereby enabling background-free detection of the light coupled out of the waveguide layer.
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Abstract
A microoptical sensor and a corresponding method 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 is effected by means of a multi-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 results in a directional separation of decoupled light from reflected, transmitted and directly diffracted sub-beams, respectively. This makes possible a background-free detection of guided light decoupled from the waveguiding layer, although 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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Citations
21 Claims
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1. A microoptical sensor for detecting chemical substances, the sensor comprising:
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a) a solid substrate; b) a planar waveguide layer located on a surface of the substrate, the planar waveguide layer having an interaction surface for contacting the chemical substances to be detected; and c) a diffractive grating located proximate to the planar waveguide layer for coupling and decoupling light into and out of the planar waveguide layer, the diffractive grating oomprising at least two superimposed gratings, (i) a first grating having a first fixed fundamental frequency and a first discrete diffraction order, the first grating acting as an input grating coupler for coupling light into the planar waveguide layer at a first discrete coupling angle, the incoupled light interacting with the chemical substances adjacent to the interaction surface and (ii) a second grating having a second fixed fundamental frequency different from the first fundamental frequency and a second discrete diffraction order different from the first diffraction order, the second grating acting as an output grating coupler for coupling light out of the planar waveguide layer at a second discrete coupling angle different from the first coupling angle, the first and second discrete coupling angles causing a detectable directional separation of light coupled into and out of the planar waveguide layer, thereby enabling background-free detection of the light coupled out of the waveguide layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification