All-glass flexible 1D photonic crystals fabricated via RF-sputtering as dichroic mirrors

The benefits obtained in terms of costs and applicability by the development of flexible and stretchable electronics, compared to their rigid counterparts, have fostered the birth of the idea of the photonics analogue. By adding mechanical flexibility to photonic structures, the fields of application expand incredibly. In particular, we are interested in 1D photonic crystals that, due to their versatility, are exploited in several applications from sensors to dichroic mirrors in photovoltaic cells. Here, a radio frequency (RF) sputtering deposition protocol is developed for fabricating dichroic mirrors on ultrathin flexible glass as well as on rigid substrates for comparison. The 1D multilayer structures, constituted by silica and hafnia layers, were first designed, and modelled by Transfer Matrix Method to tailor targeted optical features (transmission windows, stopband ranges) and then fabricated by RF-sputtering technique. The optical features of the samples, on both flexible and rigid substrates, were studied to highlight up to which extent the different nature of the substrates and the mechanical deformations are not influencing the key spectral properties of the photonic crystals.