Director induced realignment

Flows also give rise to director axis realignment (see Fig. 8.2). In the extreme case of flow, the liquid crystal is forced to vacate the site it occupied (i.e., an empty space is left). Easer-induced flow effects thus give rise to large index changes, as observed in several studies involving nanosecond or picosecond laser pulses. ... 

As the previous sections have shown, nematic polymer liquid crystals may be oriented by surface forces and in electric fields. It has been shown recently that such field-induced changes in orientation may also be used to orient pleochroic dyes through the guest-host effect. In such an effect either guest dyes dissolved in a nematic polymer " host or side-chain dye moieties in a nematic copolymer system (where A is a nematic moiety and B is a dye in Fig. 2b) undergo a cooperative realignment as the nematic director responds to the applied field. Since the pleochroic dye has its absorption transition... 

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