Óscar Gómez Calderón

Rotational dynamics in dipolar colloidal suspensions: video microscopy experiments and simulations results

Abstract The dynamics of field-induced structures in very dilute dipolar colloidal suspensions subject to rotating magnetic fields have been experimentally studied using video microscopy. When a rotating field is imposed the chain-like aggregates rotate with the magnetic field frequency. We found that the size of the induced structures at small rotational frequencies is larger than at zero rotating frequency, i.e. when an uniaxial magnetic field is applied. At higher frequencies, the average size of the aggregates decreases with frequency following a power law with exponent −0.5 as the hydrodynamic friction forces overcome the dipolar magnetic forces, causing the chains break up. A non-thermal molecular dynamics simulations are also reported, showing good agreement with the experiments.

Tunable Phase Control of Coherent Population Oscillations

We study the propagation of an amplitude modulated 1550-nm signal along an EDF pumped with an amplitude modulated 980-nm beam. A transition from super- to subluminal light depending on the phase between them is observed.

Fractional Advancement Enhancement in Erbium-Doped Fiber Amplifiers by Bi-Directional Pumping

We experimentally analyze the fractional advancement of amplitude-modulated 1550 nm signals when propagating through highly-doped erbium fibers pumped at 980 nm in different pump configurations.

Dynamic Control of the Time Delay in a Semiconductor Quantum Well

In this work we propose a scheme for coherent control of time delay of light pulses that employs quantum interference and coherence in the conduction inter-subband transitions of a double-quantum well.