Ultrafast broadband optical modulation in indium tin oxide/titanium dioxide 1D photonic crystal

Abstract

Photonic crystals can integrate plasmonic materials such as Indium Tin Oxide (ITO) in their structure. Exploiting ITO plasmonic properties, it is possible to tune the photonic band gap of the photonic crystal upon the application of an external stimuli. In this work, we have fabricated a one-dimensional multilayer photonic crystal alternating ITO and Titanium Dioxide (TiO2) via radio frequency sputtering and we have triggered its optical response with ultrafast pump-probe spectroscopy. Upon photoexcitation, we observe a change in the refractive index of ITO. Such an effect has been used to create a photonic crystal that changes its photonic bandgap in an ultrafast time scale. All optical modulation in the visible region, that can be tuned by designing the photonic crystal, has been demonstrated.