Tuning of resonant Zener tunneling by vapor diffusion and condensation in porous optical superlattices

We study a vapor-controlled optical superlattice realized with a silicon-based dielectric mesoporous material. By flowing organic vapors through the nanometer-sized pores, the position dependent refractive index can be continuously tuned, resulting in a tilted photonic band structure. A careful design of pore size distribution, close to the critical radius of capillary condensation of vapor, makes the superlattice sensitive to the flow direction. We drive the optical superlattice to the resonant Zener tunneling condition, introducing an enhanced transmission channel through the photonic crystal. Our results show that vapor capillary condensation can be used to modify the properties of optical superlattices allowing, e.g., to realize fast gas sensing devices due to their advantage to respond to vapor flow fronts.