| abstract |
A biochemical sensor device comprises a planar monomode waveguide 11 one surface of which is coated with a metal film 13 which in turn is coated with a dielectric film 14. The dielectric is as elective absorber of a material to be sensed. Light propagated through the waveguide interacts with surface plasmons in the metal film, the degree of interaction being a function of the electric field conditions adjacent the metal film. The attenuation is measured by a photodetector 16. A waveguide supporting two guided modes, only one of which exhibits resonance, may be employed, the non-resonant mode providing a reference signal. <IMAGE> |