Snake orbits and related magnetic edge states

We study the electron motion near magnetic field steps at which the strength and/or sign of the magnetic field changes. The energy spectrum for such systems is found and the electron states (bound and scattered) are compared with their corresponding classical paths. Several classical properties as the velocity parallel to the edge, the oscillation frequency perpendicular to the edge and the extent of the states are compared with their quantum mechanical counterpart. A class of magnetic edge states is found which do not have a classical counterpart.Comment: 8 pages, 10 figure

Laser-Induced Above-Bandgap Transparency in GaAs

We report the observation of large ($\sim 40$) laser-induced above-bandgap transparency in GaAs at room temperature. The induced transparency is present only during the pulse width of the driving midinfrard laser pulses and its spectral shape is consistent with a laser-induced blue shift of the band edge. Our simulations based on the dynamic Franz-Keldysh effect reproduce the salient features of the experimental results, demonstrating in particular that the amount of the band edge shift is approximately given by the ponderomtive potential.Comment: 4 pages, 4 figure

Bilateral symmetry breaking in a nonlinear Fabry-Perot cavity exhibiting optical tristability

We show the existence of a region in the parameter space that defines the field dynamics in a Fabry-Perot cylindrical cavity, where three output stable stationary states of the light are possible for a given localized incident field. Two of these states do not preserve the bilateral (i.e. left-right) symmetry of the entire system. These broken-symmetry states are the high-transmission nonlinear modes of the system. We also discuss how to excite these states.Comment: 5 pages, 5 figure