Comparison of different switching techniques in a cavity soliton laser (original) (raw)
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Cavity soliton laser based on a VCSEL with saturable absorber
Localized States in …, 2011
In this Chapter we intend to make a review on our work on cavity solitons in semiconductor lasers with saturable absorbers, with a special attention to the most recent results.We study theoretically a broad-area vertical cavity surface emitting laser (VCSEL) with a saturable absorber, and show numerically the existence of cavity solitons in the system: they exist as solitary structures superposed on a background with zero intensity. Therefore, this system can work as a cavity soliton laser, ensuring maximum contrast and compactness of the device, in comparison with other systems supporting cavity solitons. In particular, in absence of a holding beam, these solitons do not rely on a proper phase of the addressing pulses to be either created or deleted.We also show that the properties of the system are deeply influenced by the radiative recombination of carriers. Taking into account this process, the existence of solitons is shown numerically for a choice of parameters suitable to describe real devices, where the same material is used for the active and the passive parts. Furthermore, we compare three different switching techniques for the control of cavity solitons in a VCSEL based cavity soliton laser, one incoherent and the other two semicoherent with different injection frequencies. We show that the switching dynamics and energies can be very different depending on the type of injection. Finally, we show that in a cavity soliton laser based on a VCSEL with a saturable absorber the solitons can spontaneously move if the ratio of the carrier lifetimes in the amplifier and in the absorber takes appropriate values. The direction of the motion is arbitrary, while its velocity is determined by the parameters of the system. In devices with a finite cross section the CS describes different trajectories depending on the shape of the boundary of the pumped region. For a circular pump the CS moves on circular trajectories along the boundary. This dynamical regime can be exploited to create controllable trains of pulses, together with frequency and amplitude modulation.
Moving Solitons in a Cavity Soliton Laser
PIERS Online, 2009
We show that in a cavity soliton laser based on a VCSEL with a saturable absorber the solitons can spontaneously move. A key parameter ruling the dynamical instability is the ratio of the carrier lifetimes in the amplifier and in the absorber. The direction of the spontaneous motion is arbitrary but it can be controlled by injecting a low-intensity guiding beam for a short interval of time. The final velocity of the moving soliton is determined by the parameters of the system.
Cavity soliton laser based on VCSEL with saturable absorber
Applied Physics B-lasers and Optics, 2005
We study theoretically a broad-area vertical cavity surface emitting laser (VCSEL) with a saturable absorber. We show numerically the presence of cavity solitons in the system: they exist as solitary structures formed through a modulationally unstable homogeneous lasing state that coexists with a background with zero intensity. Such a peculiar scenario endows the solitons with unique properties compared to cavity solitons in most previously studied optical systems. In particular, these solitons do not as such rely on a proper phase of the addressing pulses to be either created or deleted. We show that exciting and deleting the solitons depend crucially on whether a threshold in the soliton peak has been reached.
The European Physical Journal D, 2010
We present recent experimental results on the control and dynamics of cavity solitons in a monolithic, vertical cavity surface emitting laser with saturable absorber. On one hand, the fast and independent manipulation of two laser cavity solitons is achieved and a flip-flop operation is demonstrated with a single control-beam. On the other hand, a pulsing localized structure is presented and we demonstrate the control of a pulsing multispot structure that we can switch-on and off. These results are promising in view of the obtainment of a pulsed and monolithic cavity soliton laser.
Cavity solitons in a driven VCSEL above threshold
IEEE Journal of Selected Topics in Quantum Electronics, 2000
We experimentally demonstrate the existence and the control of cavity solitons in externally driven vertical-cavity semiconductor lasers above threshold. A model including material polarization dynamics is used to predict and confirm the experimental findings.
Cavity Solitons in VCSEL Devices
Advances in Optical Technologies, 2011
We review advances on the experimental study of cavity solitons in VCSELs in the past decade. We emphasize on the design and fabrication of electrically or optically pumped broad-area VCSELs used for CSs formation and review different experimental configurations. Potential applications of CSs in the field of photonics are discussed, in particular the use of CSs for all-optical processing of information and for VCSELs characterization. Prospects on self-localization studies based on vertical cavity devices involving new physical mechanisms are also given.
Using the Lagrange method to fit the curve of maximum gain as a function of carrier density for an active region consisting of an AlGaAs/GaAs layers sandwiched between DBR layers, it is found that the curve is better approximated assuming a quadratic dependence on the carrier density. By summarizing all of the calculations into a nonlinear gain coefficient parameter, β, in the Maxwell-Bloch equations we numerically studied the effect of nonlinear gain on the characteristics of the VCSEL and also on the cavity solitons (CSs) forming in such a device. Particularly, it is shown that with nonlinear gain a wider locked region can be achieved along with enhanced sustained relaxation oscillation amplitude. The switching on/off time of CSs is modified and there appears a considerable enhancement in their efficiency and contrast.
Cavity solitons in driven VCSELs above threshold
2007
CSs have been theoretically predicted and recently experimentally demonstrated in broad area, vertical cavity driven semiconductor lasers (VCSELs) slightly below the lasing threshold. Above threshold, the simple adiabatic elimination of the polarization variable is not correct, leading to oscillatory instabilities with a spuriously high critical wave-number. To achieve real insight on the complete dynamical problem, we study here the complete system of equations and find regimes where a Hopf instability, typical of lasers above threshold, affects the lower intensity branch of the homogeneous steady state, while the higher intensity branch is unstable due to a Turing instability. Numerical results obtained by direct integration of the dynamical equations show that writable/erasable CSs are possible in this regime, sitting on unstable background
Spontaneously moving solitons in a cavity soliton laser with circular section
European Physical Journal D, 2010
We show that in a cavity soliton laser based on a VCSEL with a saturable absorber the solitons can spontaneously move if the ratio of the carrier lifetimes in the amplifier and in the absorber takes appropriate values. The velocity is determined by the parameters of the system. In devices with a finite circular cross section the solitons move on circular trajectories along the boundary. This dynamical regime can be exploited to create trains of pulses with controlled intensity, frequency and wherein a determined delay can be applied.