DEVELOPMENT OF AN OPTICAL BIOSENSOR DEVICE BASED ON GRATING ASSISTED GUIDED HYBRID-MODE EXCITATION

Evanescent wave probing of the proximity of optical interfaces is showing a considerable potential for e.g. biosensor and environmental monitoring applications. In particular, the resonance phenomenon of waveguide mode- or surface plasmon-excitation provides a very sensitive probing mechanism for the optical properties dielectric or metallic interfaces. In this paper we present a new sensor device based on the simultaneous excitation of (p-polarized) waveguide-modes and surface plasmons forming so-called hybrid-modes. This has the advantage of combining greater design flexibility and the potential for monolithic integration with the well-established technique of Surface Plasmon Resonance (SPR). The sensor consists of a metal-coated planar dielectric waveguide provided with an embossed coupling grating and a flow cell. Various numerical simulations are presented for achieving optimum sensor parameters complemented by experimental characterizations for verifying the sensor properties. The experimental part includes the preparation of the sensor device and SPR-measurements with different solutions modifying the cladding area of the sensor-chip.