Rolled-up TiO2 microtubes for photonics applications

The properties of titania (TiO2) are explored within the context of rolled-up nanotechnology, with particular attention to possible photonics applications. We show how the morphology of titania microtubes, as well as the TiO2 phase and refractive index, can be controlled by properly tuning the microfabrication parameters. High refractive index TiO2 tubes are proven to work as microresonators. The possibility of combining the rolling technique with an adequate prepatterning of the titania membrane could pave the way for the fabrication of a rolled-up diamond-like photonic crystal operating at visible frequencies, as substantiated by theory.