Irregular pulsating polarization dynamics in gain-switched vertical-cavity surface-emitting lasers

©2007 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.International audienceIn this paper, we report on experimental and theoretical investigation on the nonlinear dynamics of the two orthogonal linearly polarized fundamental transverse modes of verticalcavity surface-emitting lasers (VCSELs) under sinusoidal current modulation. Irregular pulses of the power of individual polarizations are measured with a period equal to twice the modulation period. In contrast with individual polarizations, total power displays regular pulsing at twice the modulation period. The variability of pulse streams is characterized by using residence times distributions. We show that the residence time distributions for individual linear polarizations display an exponential decay for large values of that time. Those results are well reproduced by using a theoretical model that includes spontaneous emission fluctuations. However the previous qualitative features remain even in the absence of spontaneous emission noise. Our results therefore suggest that the irregular polarization dynamics have a deterministic origin and can be defined as deterministic chaos

Noise-sustained dynamics of drifting patterns in a tilted nonlinear feedback system

We investigate experimentally the dynamics of pattern excitation in presence of an advection-like effect in a nonlinear optical system. This advection effect, created when the angle of incidence of the pump beam is not zero, causes the existence of: (i) a transition from convective to absolute instabilities, (ii) the formation of new pattern geometries, (iii) the seeding of noise-sustained structures. All these phenomena, previously observed in nonlinear Kerr-type systems, are demonstrated in our setup composed by a photorefractive nonlinear medium in a tilted feedback configuration

Polarization switching dynamics and bistability in mutually coupled vertical cavity surface emitting lasers

We theoretically investigate the polarization-resolved dynamics of two vertical-cavity surface-emitting semiconductor lasers that are mutually coupled through coherent optical injection. We find a sequence of bistable polarization switchings that can be induced by either changing the coupling strength or the optical propagation phase. The successive polarization switchings are correlated to the creation of new compound-cavity modes when these parameters are continuously varied. The switching dynamics and the role of asymetries are also discussed.The authors acknowledge financial support from MEC (Spain) and Feder, project FIS2004-00953. Josep Mulet is supported by the CSIC (Spain) through the program I3P-PC2003. Marc Sciamanna acknowledges the financial support of UIB (Spain) in the frame of a visiting professor stay.Peer reviewe

Transverse Mode Switching and Locking in Vertical-Cavity Surface-Emitting Lasers Subject to Orthogonal Optical injection

©2007 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.In this paper, we report on theoretical and experimental investigation on polarization and transverse mode behavior of vertical-cavity surface-emitting lasers (VCSELs) under orthogonal optical injection as a function of the injection strength and of the detuning between the injection frequency and the free-running frequency of the solitary laser. As the injection strength increases the VCSEL switches to the master laser polarization. We find that the injection power necessary to obtain such polarization switching is minimum at two different values of the frequency detuning: the first one corresponds to the frequency splitting between the two linearly polarized fundamental transverse modes, and the second one appears at a larger positive frequency detuning, close to the frequency difference between the first-order and the fundamental transverse modes of the solitary VCSEL. We show theoretically that both the depth and the frequency corresponding to the second minimum increase when the relative losses between the two transverse modes decrease. Bistability of the polarization switching is obtained for the whole frequency detuning range. Such a bistability is found for the fundamental mode only or for both transverse modes, depending on the value of the detuning. The theoretical and experimental optical spectra are in good agreement showing that the first-order transverse mode appears locked to the external injection

Spatiotemporal complexity of chaos in a phase-conjugate feedback laser system

International audienceAn 852 nm semiconductor laser is experimentally subjected to phase-conjugate time-delayed feedback achieved through four-wave mixing in a photorefractive (BaTiO3) crystal. Permutation entropy (PE) is used to uncover distinctive temporal signatures corresponding to the sub-harmonics of the round-trip time and the relaxation oscillations. Complex spatiotemporal outputs with high PE mostly upwards of ∼0.85 and chaos bandwidth (BW) up to ∼31GHz are observed over feedback strengths up to 7%. The low-feedback region counterintuitively exhibits spatiotemporal reorganization, and the variation in the chaos BW is restricted within a small range of 1.66 GHz, marking the transition between the dynamics driven by the relaxation oscillations and the external cavity round-trip time. The immunity of the chaos BW and the complexity against such spatiotemporal reorganization show promise as an excellent candidate for secure communication applications

Control of pattern formation in a single feedback system by photonic lattices

We present the observation of the manipulation of modulational instability in a nonlinear dissipative system by a periodic photonic lattice. We use a setup based on a photorefractive BaTiO3 crystal in a single feedback mirror configuration leading to the formation of hexagonal patterns. Additionally, we impose an optical lattice to induce one or two-dimensional photonic band-gap structures with variable parameters. We show that by varying the lattice periodicity, thus adjusting the transverse spatial frequencies associated to the bandgap, we can induce patterns of particular symmetry or suppress the modulational instability when the position of the lattice bandgap coincides with the instability gain

Experimental evidence of coherence resonance in a time-delayed bistable system

We report on the experimental observation of coherence resonance in a bistable system with delay. Our system consists of a vertical-cavity surface-emitting laser subject to time-delayed optical feedback simultaneously from a long and from an extremely short external cavity. Coherence resonance is experimentally proven by analysis of the residence time distribution of the polarization mode-hopping regime and of the signal to noise ratio in the power spectrum.The authors acknowledge the financial support of the Public University of Navarra, IAP 6/10 —Belgian Science Policy, FWO Flanders, GOA and OZR of the VUB, Conseil Regional de Lorraine, and Project No. TEC-2004-05936-C02-01 of the MEC (Spain)

Modulational instability and solitons in a periodic dissipative feedback system

International audienceWe review our recent experimental results on control of the modulational instability, pattern formation, and solitons in a nonlinear discrete dissipative feedback system. We show that the discreetness and bandgap effects can provide efficient control of the nonlinear instability modes of the system. Furthermore, we explore the possibilities for excitation of dissipative discrete solitons in such system through seeding with a narrow addressing beam

Passively mode-locked high-frequency dual-VCSEL system

Two VCSELs placed facing each other with one biased chip while the second chip is unbiased is shown as a promising alternative to the popularly used conventional SESAM mode-locked VECSEL to generate mode-locked pulses. We propose a theoretical model using time-delay differential rate equations and numerically show that the proposed dual-laser configuration functions as a typical gain-absorber system. Parameter space defined by laser facet reflectivities and current are used to show general trends in the exhibited nonlinear dynamics and pulsed solutions