  In this work we describe different types of photonic structures that allow
tunability of the photonic band gap upon the application of external stimuli,
as the electric or magnetic field. We review and compare two porous 1D photonic
crystals: in the first one a liquid crystal has been infiltrated in the pores
of the nanoparticle network, while in the second one the optical response to
the electric field of metallic nanoparticles has been exploited. Then, we
present a 1D photonic crystal made with indium tin oxide (ITO) nanoparticles,
and we propose this system for electro-optic tuning. Finally, we describe a
microcavity with a defect mode that is tuned in the near infrared by the
magnetic field, envisaging a contact-less magneto-optic switch. These optical
switches can find applications in ICT and electrochromic windows.
