1D photonic crystals fabricated by RF sputtering

The benefits obtained in terms of costs and applicability by the development of flexible and stretchable electronics, compared to its rigid counterpart, have fostered the quest for flexible photonic technologies and integrated platforms on suitable material systems. By adding mechanical flexibility to photonic structures, novel functionalities would be added to their already broad range of applications. Aside of the research and innovation on flexible photonics on organic platforms, recently a new approach is gaining more and more interest, which relies on the use of inorganic all-glass thin structures. In case of oxides, their typical qualifying properties in terms of transparency, high thermal and chemical resistance could be exploited in suitable material systems. Here it is presented two flexible SiO2/HfO2 1D photonic crystals, fabricated by radio frequency sputtering. As expected, the systems show a strong dependence of the optical features on the light incident angle: i) blue-shift of the stopband and ii) narrowing of the reflectance window. Nevertheless, the most interesting result is the experimental evidence that, even after the sample breakage, where the flexible glass shows naked-eye visible cracks, the multilayer structures generally maintain their integrity, resulting to be promising systems for flexible photonic applications thanks to their optical, thermal and mechanical stability.