Nonlinearities In Quantum Wells Research Articles

All-optical bistable switching in curved microfiber-coupled photonic crystal resonators

The authors report low-power optical bistability under continuous wave pumping conditions in five-cell photonic crystal linear resonators containing InGaAsP quantum wells, by employing the fiber-coupling technique. The threshold bistable power is measured to be 35μW at the normalized detuning of −1.724. Owing to the high band-edge nonlinearities of quantum wells and the efficient fiber coupling, minimal instability is observed. In addition, all-optical switching is demonstrated with switching energy less than 75.4fJ.

Adiabatic nonperturbative derivation of electric-field-induced optical nonlinearities in quantum wells.

We show that, for dc electric fields easily applicable to quantum wells, and for optical fields close to a transition frequency, the nonlinear susceptibilities derived from perturbation theory diverge. Alternatively, a general expression for the susceptibility based on solving the adiabatic quantum-well problem is presented, leading to a radically different behavior at large fields. Our approach is valid at low modulating rates for any system which is soluble under an applied electric field

Coulomb enhancement of the third-order optical nonlinearities in quantum wells

The investigation of Khurgin and Li [Appl. Phys. A 53, 527 (1991)] on the electrostatic Coulomb enhancement of the third-order intersubband nonlinearities in stepped quantum wells is extended by taking into account the modification of the intersubband resonant energy by the depolarization effect. It was found that the ratio of the depolarization enhancement factor (ηd) to the electrostatic Coulomb enhancement factor (ηe) strongly depends on the shape of the quantum well. Obtained results show that, in the case of the conventional square quantum well, factor ηd is several times larger than ηe while in strongly asymmetric stepped quantum wells ηd≪ηe.