Optical activity wave guides

Chiral polymers have been applied in many areas of research, including chiral separation of organic molecules, asymmetric induction in organic synthesis, and wave guiding in non-linear optics [ 146,147]. Two distinct classes of polymers represent these optically active materials those with induced chirality based on the catalyst and polymerization mechanism and those produced from chiral monomers. Achiral monomers like propylene have been polymerized stereoselectively using chiral initiators or catalysts yielding isotactic, helical polymers [148-150]. On the other hand, polymerization of chiral monomers such as diepoxides, dimethacrylates, diisocyanides, and vinyl ethers yields chiral polymers by incorporation of chirality into the main chain of the polymer or as a pedant side group [151-155]. A number of chiral metathesis catalysts have been made, and they have proven useful in asymmetric ROM as well as in stereospecific polymerization of norbornene and norbornadiene [ 156-159]. This section of the review will focus on the ADMET polymerization of chiral monomers as a method of chiral polymer synthesis. 

The three dimensional refi active indices of the fi eestanding PANI films were characterized with a modified prism-wave guide coupler (Metricon PC-2010) at 1550nm. The technique was previously developed and tested on a range of different fi-eestanding and spin coated polymer films[7,8] In this work Nz is the refi active index along the optical symmetry axis, Ny is the refi active index perpendicular to the symmetry axis in the film plane, while Nx is the refi active index normal to the film... 

In addition to studies of diacetylene single crystals, current research, activities are focused on studies of the second X and third x order nonlinear optical responses of disubstituted diacetylene polymer films as active optical guided wave structures. Diacetylene polymers possess X values comparable to germanium(j 7). In the first stage, three major questions are being addressed ... 

As in electronics in integrated optics, one has to distinguish between passive and active waveguiding components. A simple waveguide is a passive component. Active components enable controlled variations of the guided wave to be performed with respect to phase, amplitude, frequency, polarisation and direction of propagation. All these active components are either modulators or light emitters and amplifiers and detectors. 

Another model-free method for active damage detection is based on directional transducers. For passive sensing. Section 16.9 has already discussed the use of directional strain rosettes (both piezo and optical) to effectively detect an acoustic source without the need for a structural model. For active sensing, directional transmission as well as reception of guided wave can be achieved with phased-array transducers. 

The recent surge of activity in planar optical waveguides was initiated by the development of practical and efficient ways to couple light between guided modes and beams in free space. These techniques are based on the introduction of an additional element to the wave-... 

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