“…The complication in achieving this goal derives from the fact that the most common materials used in photonics, such as glass for fiber optics and silicon for integrated photonics, hardly change their optical properties, even under intense optical or electrical stimuli. For this reason, optical modulation and switching, and more generally tunability, are usually reached by means of free-carrier injection, chemical and mechanical activation, or by deploying materials with large electro-optic or optical nonlinear coefficients [ 3 , 4 , 5 , 6 , 7 ]. All these mechanisms are inherently weak and require intense control signals and long interaction lengths in order to produce significant optical modulation.…”