Field-induced barrier transparency of Bloch waves in tight-binding lattices

A rectangular potential barrier for a Bloch particle in a tight-binding lattice is shown to become fully transparent by the application of a strong ac field with appropriate amplitude and frequency. Such a curious phenomenon bears some connection with the field-induced barrier transparency effect known for freely-moving particles scattered by an ac-driven rectangular barrier; however, for a Bloch particle transparency is not related to a resonant tunnneling process across the cycle-averaged oscillating potential barrier, as for the freely-moving quantum particle. The phenomenon of field-induced transparency is specifically discussed here for photonic transport in waveguide arrays and demonstrated by full numerical simulations of the paraxial (Schr\"{o}dinger) wave equation beyond the tight-binding approximation.