Waveguide properties surfaces

Multilayer Langmuir-Blodgett films doped with a cyanine dye have been deposited on the surface of a quartz multimode optical fiber and the fluorescence properties investigated. 49 The fluorescence intensity of the films was found to be a periodic function of the number of layers due to the waveguide properties of the films. 

The intense fluorescence of laser-dyes embodied in these thin-film glasses, the simplicity to cast these sol-gel glasses in a multilayered sequence of tailored indices of refraction and the waveguide properties observed in such assemblies imply that such multilayered films may be constructed into a surface-laser. Currently, we are examining these structures as the core of a two dimensional laser and other non-linear optical devices. 

Guided mode calculations were also carried out to compare the sensor response of several waveguide systems. In these simulations a model molecular monolayer is represented by a 2-nm thick layer with a refractive index of n 1.5. The optical properties of this model layer are typical of a dense layer of organic molecules on a substrate1 41, and are a reasonable approximation for a streptavidin protein layer bound to a biotinylated surface, the experimental model system we use to characterize our sensors. The ambient upper cladding was assumed to be water with a refractive index of n 1.32. For all examples, the lower cladding was assumed to be Si02 with an index of n 1.44. In the simulations, the effective index of... 

This study represents the first systemmatic application of the optical waveguide technique to the study of the response of polymer film coatings to condensed vapor molecules. These results indicate that the technique is useful for surveying rapidly potential polymeric films as possible vapor sensor coatings. Moreover, this work has further substantiated that the vapor pressure is an important physical property to be taken into account when employing polymeric films as surface coatings. 

When optical anisotropies form spontaneously in the polymeric film during deposition, the situation is more complicated. Significant effects are observed in optical and spectroscopic properties, such as LED emission [17] and waveguide propagation [45-50,52,64], For these films, accurate evaluation of the optical constants is more difficult and must be based on variable incidence angle measurements, as in the case of surface plasmon resonance [45-47], waveguide propagation [48-50,52], ellipsometry [64,67], and reflectance/transmittance [68]. 

Distributed circuit methods use coaxial lines, waveguides and resonant cavities at microwave frequencies. The circuits are designed for measuring an attenuation factor and a phase factor, from which sample dielectric properties can be calculated. The sample may form the dielectric medium between the two conductors of a coaxial line (Scaife et al, 1971), or an open coaxial line is brought into contact with the sample surface (Roussy and Pearce, 1995). Fagan et al, (2004) used an open coaxial line method to demonstrate that the moisture and salt contents of processed cheese could be predicted by measuring dielectric properties over a range of frequencies. 

Next, we consider the absorbance due to a dichroic adlayer adsorbed onto the waveguide surface with the optical constants as indicated in Fig. 4. The optical properties of the dichroic layer are described by the different extinction coefficients k, ky, and k in each Cartesian direction. The reflectance of the waveguide-adlayer-cover system follows the analysis found in Macleod [9] with the anisotropic coefficients taken from Horowitz and Mendes [10]. By assuming a thin and weakly absorbing adlayer, the following expressions are obtained for the absorbance as measured through a guided mode at each polarization [8] ... 

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