We report on what we believe is the first demonstration of an opticallyactivated cantilever due to photomechanical effects in a dye-doped polymeroptical fiber. The fiber is observed to bend when light is launched off-axis.The displacement angle monotonically increases as a function of the distancebetween the illumination point and the fiber axis, and is consistent withdifferential light-induced length changes. The photothermal andphoto-reorientation mechanisms, each with its own distinct response time, areproposed to explain the observed time dependence. The measured degree ofbending is consistent with a model that we have proposed which includescoupling between photoisomerization and heating. Most importantly, we havediscovered that at high light intensity, a cooperative release of stressresults in cis-to-trans isomerization that yields a large and abrupt lengthchange.
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