Waveguiding of light

Studies of the waveguiding of light in multilayers of certain polymers showed that it is possible to propagate light with an attenuation that is still large compared to many other materials but small compared to other LB materials... 

Efficiency. Efficiency of a device can be reported in terms of an internal quantum efficiency (photons generated/electrons injected). The external quantum efficiency often reported is lower, since this counts only those photons that escape the device. Typically only a fraction of photons escape, due to refraction and waveguiding of light at the glass interface (65). The external efficiency can be increased through the use of shaped substrates (60). 

The most recently introduced optical teclmique is based on the retardation of light guided in an optical waveguide when biomolecules of a polarizability different from that of the solvent they displace are adsorbed at the waveguide surface (optical waveguide lightmode spectroscopy, OWLS) [H]. It is even more sensitive than ellipsometry, and the mode... 

Fig. 2. Waveguide stmcture showiag the total internal reflection of light. The diameter, is 50 p.m for a standard multimode system, 62.5 p.m for a large...

In recent years, the evolution of the technological components required for IR sensor systems has been denoted by a significant miniaturisation of light sources, optics and detectors. Essentially, an IR sensor consists of (i) a polychromatic or monochromatic radiation source, (ii) a sensor head and (iii) a spectral analyser with a detector. As sensors where all optical elements can be included in the sensor head are the exception rather than the rule, also various optics, waveguides and filters may form essential parts of IR-optical chemical sensors. Another important building block, in particular when aiming at sensors capable of detecting trace levels, are modifications of the sensor element itself. 

Veldhuis G.J., Parriaux O., Hoekstra H.J.W.M., Lambeck P.V., Sensitivity enhancement in evanescent optical waveguide sensors, J of Light. Tecnol. 2000 18 677-682. 

Fig. 9.2 Views of (a) a simple ridge waveguide and (b) a channel waveguide on a semiconductor substrate. The arrow indicates the direction of light propagation...

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