We report on the first experimental observation of spontaneous mirror symmetry breaking (SSB) in coherently driven-dissipative coupled optical cavities. SSB is observed as the breaking of the spatial ...or mirror Z_{2} symmetry between two symmetrically pumped and evanescently coupled photonic crystal nanocavities, and manifests itself as random intensity localization in one of the two cavities. We show that, in a system featuring repulsive boson interactions (U>0), the observation of a pure pitchfork bifurcation requires negative photon hopping energies (J<0), which we have realized in our photonic crystal molecule. SSB is observed over a wide range of the two-dimensional parameter space of driving intensity and detuning, where we also find a region that exhibits bistable symmetric behavior. Our results pave the way for the experimental study of limit cycles and deterministic chaos arising from SSB, as well as the study of nonclassical photon correlations close to SSB transitions.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
Injection-locked semiconductor lasers can be brought to a neuronlike excitable regime when parameters are set close to the unlocking transition. Here we study experimentally the response of this ...system to repeated optical perturbations and observe the existence of a refractory period during which perturbations are not able to elicit an excitable response. The results are analyzed via simulations of a set of dynamical equations which reproduced adequately the experimental results.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
In spite of numerous theoretical and experimental reports of excitability in lasers with injected signal based on the locking-unlocking transition, the response of the system to controlled external ...perturbations (which is at the basis of the definition of excitable systems) has not been experimentally studied yet. In the following, we analyze the response of an injection-locked semiconductor laser to different external perturbations. We demonstrate the existence of a perturbation threshold beyond which the response of the system is independent of the strength of the stimulation and, thus, demonstrate its excitable character. We show that optically perturbing such an excitable system via the control of the phase of the injection beam can be useful for optical pulse generation.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Although machine learning (ML) algorithms are already applied in many fields (e.g. language recognition, temporal series prediction) using software computed on "Von Neumann" architectures, numerous ...technological advances (e.g. robotics, autonomous driving) require dedicated hardware. Integrated optics constitute a highly promising platform that could be harnessed for achieving portable ML chips with unprecedented power-efficiency and bandwidth 1. Despite recent observations of ML key functionalities using integrated Silicon photonics, such as reconfigurable matrix multiplication 2 and nonlinear activation functions 3, excitability observation, the spiking mechanism of our biological neurons, remains incomplete in all-integrated systems; they are based on opto-thermal (slow) effects 4 that drastically limits its applicability in ML systems with high bandwidth requirements. Here, we use InP-based photonic crystal nanocavities heterogeneously integrated on top of a Silicon on Insulator (SOI) waveguide to demonstrate the first all-integrated (fast) excitable nanolaser.
Future optical networks will require processing of phase and not only intensity encoded information. We demonstrate the regeneration and storage of optical phase bits in an experimental device based ...on semiconductor laser with coherent optical injection and delayed retro-action.
Excitable systems (known for their all or nothing and well calibrated response to external perturbations) are obvious candidates for the handling of binary data. In this contribution, we demonstrate ...experimentally that a semiconductor laser based excitable system placed in an optical feedback loop can act as a buffer for optical data. In the process, we demonstrate the existence and control of topological localized states in optics.
Reengineering has become a fact of life for all professionals in the healthcare industry. It is a time of dynamic change and challenge. This article describes ways in which healthcare professionals ...can assess the situation, evaluate the environment, and actively participate and cope with changes—in other words, ways to “survive” the process of reengineering.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
PDF
