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arXiv · 1403.6359

Coexistence of fast photodarkening and slow photobleaching in Ge19As21Se60 thin films

Pritam Khan·A. R. Barik·E. M. Vinod·K. S. Sangunni·H. Jain·K. V. Adarsh
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Abstract

We experimentally demonstrate the coexistence of two opposite photo-effects, viz. fast photodarkening (PD) and slow photobleaching (PB) in Ge19As21Se60 thin films, when illuminated with a laser of wavelength 671nm, PD appears to begin instantaneously upon light illumination and saturates in tens of seconds. By comparison, PB is a slower process that starts only after PD has saturated. Although we could observe the coexistence of PD/PB even at moderate, one order of magnitude lower intensity of 0.2 W/cm2, the kinetics of transformation is significantly slowed down. However, both PD and PB follow stretched exponetial dependence on time. Modeling of overall change as a linear sum of two contributions suggests that the changes in As and Ge parts of glass network respond to light indepndent of each other.

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Pritam Khan, A. R. Barik, E. M. Vinod, K. S. Sangunni, H. Jain, K. V. Adarsh. 2014-03-25. Coexistence of fast photodarkening and slow photobleaching in Ge19As21Se60 thin films. https://doi.org/10.1364/oe.20.012416

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