Refractive indices internal absorption

Internal redection starts by consideration of an interface between two media, a denser transparent medium with refractive index n, and a rarer medium with a complex refractive index (= where is the absorption coefficient of the medium) as shown in Figure 23. If of the rarer... 

Accounting for the effect of the host material on the interactions between the dipoles involves the refractive index, the relative orientation of the charges, and the local or internal field. The local or internal field problem is associated with the fact that molecules in a host medium occupy a particular volume or a cavity . This cavity description has been used to formalize the description of interactions between dipoles. The region occupied by the molecule results in an additional correction so the field acting on the molecule will be an effective local field rather than the mean macroscopic field. The field acting on the molecule may be an applied electromagnetic field (such as in absorption), the effect of another dipole or a combination of the two. 

For water droplets (m = 1.33), a plot of Qext versus a is shown in Fig. 16.3. Oscillations in the value of Qext are due to internally reflected light being in or out of phase during scattering. Also shown is a plot for a material having the same real refractive index as water but a small and intermediate absorption component (m = 1.33 - O.Oli and m = 1.33 - O.lz). The effect of absorption on oscillations in Qext as the absorption component increases can be clearly seen. 

The problem of the optical characteristics of the aerosols, soot particles included, was discussed at the First International Workshop on Light Absorption by Aerosol Particles (IWLAAP) [24]. The real part, , of the StA complex refractive index in the visible (0.3-0.7 Pm), according to V. Egan [24], varies from 1.665 to 1.775 (w c 2.0-li, for the visible). 

The sample is placed in contact with the internal reflection element, the light is totally reflected, and the sample interacts with the evanescent wave resulting in the absorption of radiation by the sample. The internal reflection element is made from a material with a high refractive index, e.g., zinc selenide (ZnSe) or silicon (Si). 

Keywords Absorption ARROW waveguide Biosensor Chemical sensor Confinement Dielectrics Evanescent field Fiber optics Fluorescence Hollow core Liquid-core Loss Optical mode Photonic crystal Refractive index Resolution Scattering Sensitivity Total internal reflection Waveguide... 

The absorption of the evanescent wave. The evanescent wave is the component of the totally internally reflected wave that penetrates into the medium of lower refractive index (i.e. the cladding) by a distance that depends on the angle of incidence. This is illustrated in... 

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