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Photoexpansion and photobleaching effects in oxysulfide thin films of the GeS2+Ga2O3 system |
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| Authors: | AC Mendes LJQ Maia SH MessaddeqY Messaddeq SJL RibeiroM Siu Li |
| Institution: | a Instituto de Física de São Carlos, Universidade de São Paulo, C.P. 369, CEP 13566-590, São Carlos, SP, Brazil b Instituto de Física, Universidade Federal de Goiás, C.P. 131, CEP 74001-970, Goiânia, GO, Brazil c Instituto de Química, UNESP Araraquara, C.P. 355, CEP 14801-970, Araraquara, SP, Brazil |
| Abstract: | Oxysulfide systems undergo structural transformations upon illumination with laser light of near bandgap energy, as well as chalcogenide materials (glasses and films). In this paper, photoinduced effects such as photoexpansion and photobleaching were observed in GeS2+Ga2O3 (GGSO) films synthesized by electron beam evaporation. A surface expansion of the thin films and a shift to shorter wavelengths of the optical absorption edge were observed as a result of UV laser irradiation (wavelength of 351 nm) and they are dependent on laser power density, exposure time and film composition. These parameters were varied to evaluate and enhance the observed effects. In addition, the irradiated GGSO samples exhibited a decrease in refractive index, measured with a prism-coupling technique, which makes these films suitable candidates for applications as gratings and waveguides in integrated optics. |
| Keywords: | Oxysulfide Optical bandgap Photoexpansion Photobleaching Thin films |
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