We show that the transition of free particles (regardless of their mass) through a periodically driven potential barrier can be almost 100%, although the probability of tunneling through the static potential barrier is almost zero. The conditions for this to happen are discussed and physical candidates for field-induced transparency are examined.

We report on tunneling enhancement in a periodically perturbed double well system. The double well system was realized by a structure of two optical waveguides. The transfer of light power from one waveguide to the another as induced by the periodic variations of the waveguide geometry was investigated. Our experimental measurements show that, in the presence of periodic perturbation, this transfer of light power can be enhanced by more than 500 times. We use an analogy between electromagnetic wave optics and the quantum wave phenomena to provide an experimental support to the theoretical model of tunneling enhancement of a quantum particle, facilitated by its interaction with auxiliary quantum states.

No abstract

A novel adiabatic mode multiplexer enables a 2 x 2 optical switch whose operation does not depend on accumulated phase due to evanescent coupling between waveguides. The adiabatic mode multiplexer has a negligible insertion loss over C+L bands and modal cross talk better than -40 dB for any polarization state. Mode multiplexing is achieved by adiabatic transition from the fundamental mode of the single-mode waveguide to the higher mode of the multimode waveguide. Experimental measurement results for a device realized in silica-on-silicon technology are presented. By directly measuring the nonadiabatic transition probability, we show that the adiabatic mode multiplexer operates in the Landau-Zener regime.

The exchange of power between two identical coupled waveguides with embedded periodic structure along the z direction is studied in the framework of Floquet-Bloch theory. A one-period propagator is calculated and a spectrum of its eigenvalues (eigenphases) is studied. We show that due to special symmetry properties of the Floquet-Bloch operator, a strong enhancement or a total suppression of power exchange can be obtained. The power exchange control is realized by the interaction of lowest order waveguide modes with high-order modes. A numerical example is presented in which the beat length is shortened by more than five orders of magnitude.