K. Al Naimee

Mixed mode oscillations and chaotic spiking in Quantum Dot Light Emitting Diodes

We report both experimentally and theoretically the appearance of Mixed Mode Oscillations and chaotic spiking in Quantum Dot Light Emitting Diode. The proposed dimensionless model exhibits homoclinic chaos Furthermore, it is also able to reproduce Mixed Mode Oscillations and chaotic spiking regimes. The chaotic dynamics is completely determined by the variation of the injecting bias current and modulating current of the carrier in the wetting layer, as evidenced by means of the modulation depth of the system and bifurcation diagram. The influence of the injecting current on the transition between Mixed Mode Oscillations and chaos has been also investigated.

Fourier projection method for measuring the two-point correlation of Laguerre?Gaussian modes

The spatial distribution and signature of vorticity of Laguerre–Gaussian modes is analysed by measuring the two-point spatial correlation function of the one-dimensional projection of the vortex field. We describe an interferometric approach, based on a Fourier projection algorithm, for the experimental determination of the two-point correlation function of the full complex vortex field at the cross-section plane of the recorded interference pattern. The two-point correlation at any transverse plane along the beam axis is retrieved by the angular spectrum of plane waves technique, allowing us to characterize the vortex structure and spatial coherence along the direction of propagation.

Polarization dynamics in a transverse multimode class b laser: Role of the optical feedback

We investigate the polarization dynamics in a quasi-isotropic CO2 laser emitting on the annular mode subjected to an optical feedback. We observe a complex dynamics in which spatial mode and polarization competition are involved. The observed dynamics is well reproduced by a model that discriminates between the intrinsic asymmetry due to the kinetic coupling of molecules with different angular momenta and the anisotropy induced by the polarization feedback. We observe various dynamical regimes including chaotic dynamics and show that feedback changes these states from regular to chaotic and vice versa. Such a dynamics is also accompanied by spontaneous between the patterns that indicate the existence of bistability in the system. Finally the possible applications to polarization coding are discussed.

Polarization spatial dynamics in a transverse multimode CO 2 laser with optical feedback

We experimentally study the polarization dynamics in a quasi isotropic CO2 laser emitting on the TEM*01 mode subjected to an optical feedback. We observe a complex dynamics in which spatial mode and polarization competition are involved. The observed dynamic is well reproduced by means of a model that provides a quantitative discrimination between the intrinsic asymmetry due to the kinetic coupling of molecules with different angular momenta and the anisotropy induced by the polarization feedback. Possible applications to polarization coding and synchronization will be presented.

Polarized optical feedback and noise effects on CO2 laser polarization dynamics: spatial and temporal behavior

We present the role of the discharge current and noise on the polarization dynamics in the CO2 laser, showing a transition from stable to bistable states and the presence of coherent resonance. We also explore the role of an optical feedback to achieve polarization stabilization or alternation between first-order transverse modes.

Polarization Coding in CO2 Lasers: Spatial and Temporal Behavior

We study the polarization dynamics in a CO2 laser, showing a transition from stable to bistable states and the presence of coherent resonance when noise is added. We discuss the role of optical feedback to achieve polarization stabilization or alternation between first order transverse modes. We discuss the potential applications of this dynamics showing that polarization of a given transverse mode can be controlled by means of a suitable polarized optical feedback. In this way, information can be encoded in the polarization process and it can be safely recovered at an identical laser receiver synchronized with the sender.