Quantifying the statistical complexity of low-frequency fluctuations in semiconductor lasers with optical feedback
- Departament de Fisica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Campus de Terrassa, Edif. GAIA, Rambla de Sant Nebridi s/n, Terrassa E-08222 Barcelona (Spain)
- Departamento de Fisica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627 Campus Pampulha, C.P. 702, 30123-970 Belo Horizonte, MG (Brazil)
Low-frequency fluctuations (LFFs) represent a dynamical instability that occurs in semiconductor lasers when they are operated near the lasing threshold and subject to moderate optical feedback. LFFs consist of sudden power dropouts followed by gradual, stepwise recoveries. We analyze experimental time series of intensity dropouts and quantify the complexity of the underlying dynamics employing two tools from information theory, namely, Shannon's entropy and the Martin, Plastino, and Rosso statistical complexity measure. These measures are computed using a method based on ordinal patterns, by which the relative length and ordering of consecutive interdropout intervals (i.e., the time intervals between consecutive intensity dropouts) are analyzed, disregarding the precise timing of the dropouts and the absolute durations of the interdropout intervals. We show that this methodology is suitable for quantifying subtle characteristics of the LFFs, and in particular the transition to fully developed chaos that takes place when the laser's pump current is increased. Our method shows that the statistical complexity of the laser does not increase continuously with the pump current, but levels off before reaching the coherence collapse regime. This behavior coincides with that of the first- and second-order correlations of the interdropout intervals, suggesting that these correlations, and not the chaotic behavior, are what determine the level of complexity of the laser's dynamics. These results hold for two different dynamical regimes, namely, sustained LFFs and coexistence between LFFs and steady-state emission.
- OSTI ID:
- 21443014
- Journal Information:
- Physical Review. A, Journal Name: Physical Review. A Journal Issue: 1 Vol. 82; ISSN 1050-2947; ISSN PLRAAN
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
CHAOS THEORY
CORRELATIONS
CURRENTS
ELECTRIC CURRENTS
ELECTRICAL PUMPING
ELECTROMAGNETIC RADIATION
EMISSION
ENTROPY
FEEDBACK
FLUCTUATIONS
INSTABILITY
LASER RADIATION
LASERS
MATHEMATICS
PHOTON EMISSION
PHYSICAL PROPERTIES
PUMPING
RADIATIONS
SEMICONDUCTOR DEVICES
SEMICONDUCTOR LASERS
SOLID STATE LASERS
STEADY-STATE CONDITIONS
THERMODYNAMIC PROPERTIES
VARIATIONS