Timescale dependent sign of amorphous titanium dioxide thermo-optic coefficient
Résumé
We report on the thermo-optic properties of electron-beam evaporated amorphous titanium dioxide (TiO 2 ) at different timescales. We investigate the thermo-optic response of TiO 2 from static regime down to the micro-second regime by applying Joule heating on hybrid metallo-dielectric integrated Mach-Zehnder interferometers. We show that amorphous TiO 2 exhibits a very large negative thermo-optical coefficient in the range of -6.5×10 −4 K −1 at 1550 nm at typical timescales of a few seconds. Such a slow thermo-optic response is consistent with an organic origin of amorphous TiO 2 negative thermo-optic coefficient. However, when observed at the micro-second timescale, we show that the same amorphous TiO 2 has a positive thermo-optic coefficient, just like many other materials. Based on our results, TiO 2 can be conveniently deployed in energy-effective integrated optic devices by taking into account the specific multi-timescale thermo-optic properties of this material.
Domaines
Sciences de l'ingénieur [physics]
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