ABSTRACT
We study the slow-light performance in the presence of exciton-exciton interaction in films of linear molecular aggregates at the nanometer scale. In particular, we consider a four-level model to describe the creation/annihilation of two-exciton states that are relevant for high-intensity fields. Numerical simulations show delays comparable to those obtained for longer propagation distances in other media. Two-exciton dynamics could lead to larger fractional delays, even in presence of disorder, in comparison to the two-level approximation. We conclude that slow-light performance is a robust phenomenon in these systems under the increasing complexity of the two-exciton dynamics.
ABSTRACT
We have observed extreme nonlinear optical phenomena produced by intense midinfrared (MIR) pulses in semiconductors. These phenomena include multiple off-resonance optical sidebands (up to +/-3 MIR photons interacting with a near-infrared photon), multiple MIR harmonics (up to the seventh harmonic), and significant broadening and modification of MIR harmonic spectra. The generation of these extreme MIR nonlinear optical phenomena is primarily aided by cross-phase modulation.
ABSTRACT
We present evidence of stochastic resonance in free-electron lasers. In order to do that, we have analyzed theoretically the dynamics of a free-electron laser oscillator. A weak modulation and a noise source have been applied to the initial energy of the electron beam. We have found stochastic resonance for different frequencies and amplitudes of the modulation. A threshold crossing mechanism leads to the stochastic resonance in this system.