Waveguide physics

W. H. Butler, X.-G. Zhang, D. M. C. Nicholson, T. C. Schulthess, and J. M. MacLaren, Giant Magnetoresistance from an Elecuon Waveguide Effect in Cobalt-Copper Multilayers , Physical Review Letters 76, pp.3216-3219, (1996). 

Optical sensors (Figure 1) can be defined as devices for optical monitoring of physical parameters (pressure1, temperature2, etc.) or (bio)chemical properties of a medium by means of optical elements (planar optical waveguides or optical fibres). Chemical or biochemical fibre-optic sensors3 are small devices capable of continuously and reversibly recording the concentration of a (bio)chemical species constructed be means of optical fibres. 

Fig. 8.22 Scanning electron micrograph shows a polystyrene microring coupled to a bus wave guide and sandwiched by two waveguide offsets. Reprinted from Ref. 49 with permission. 2008 American Institute of Physics...

Various sensor arrangements depend on the actual way how the shift in the mode s effective refractive index is followed. In order to design a sensitive waveguide sensor and to quantify the refractive index changes, the effective refractive index has to be connected with the physical parameters of the waveguide. To this end, one needs to solve the Maxwell s equations using the appropriate boundary conditions10. 

N. Moll, and G.-L. Bona, Comparison of three-dimensional photonic crystal slab waveguides with two-dimensional photonic crystal waveguides efficient butt coupling into these photonic crystal waveguides. Journal of Applied Physics 93, 4986-4991 (2003). 

Antibodies are commonly used for the capture of target molecules on the waveguides and they are immobilized by either physical adsorption or through a self-assembly monolayer (SAM). In the former situation. 

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