A novel all‐optical light modulation has been proposed based on photoinduced changes of an imaginary part of complex refractive index in guided wave geometry. Very fast and repeated modulation of a reading beam (reflected intensity) was demonstrated at the incident angle corresponding to a sharp guided wave resonance using phthalocyanine‐doped poly(vinyl alcohol) film as a photoresponsive layer and a nanosecond pulsed laser as a writing beam. Such responses were mainly due to the formation and decay of excited triplet phthalocyanine. The rise and fall time was markedly improved as compared with previous systems based on photothermal changes of the refractive index.

Topics
Waveguides, Dye doped polymers, Optical properties, Thermo optic effects, Lasers, Photoexcitations, Chemical compounds
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© 1996 American Institute of Physics.
1996
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