title: Correlations in electrically coupled chaotic lasers.
abstract: We show how two electrically coupled semiconductor lasers having optical feedback can present simultaneous antiphase correlated fast power fluctuations, and strong in-phase synchronized spikes of chaotic power drops. This quite counterintuitive phenomenon is demonstrated experimentally and confirmed by numerical solutions of a deterministic dynamical system of rate equations. The occurrence of negative and positive cross correlation between parts of a complex system according to time scales, as proved in our simple arrangement, is relevant for the understanding and characterization of collective properties in complex networks.
authors.affiliation: Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Cidade Universitária, Recife, PE, Brazil.
authors.forename: E J
authors.initials: EJ
authors.lastname: Rosero
authors.affiliation: Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Cidade Universitária, Recife, PE, Brazil.
authors.forename: W A S
authors.initials: WA
authors.lastname: Barbosa
authors.affiliation: Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Cidade Universitária, Recife, PE, Brazil.|Departamento de Física, Universidade Federal de Sergipe, Av. Marechal Rondon, S/N Jardim Rosa Elze, 49100-000 São Cristóvão, SE, Brazil.
authors.forename: J F
authors.initials: JF
authors.lastname: Martinez Avila
authors.affiliation: Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Cidade Universitária, Recife, PE, Brazil.|Instituto de Física, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza S/N, 24210-346 Niteroi, RJ, Brazil.
authors.forename: A Z
authors.initials: AZ
authors.lastname: Khoury
authors.affiliation: Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Cidade Universitária, Recife, PE, Brazil.
authors.forename: J R
authors.initials: JR
authors.lastname: Rios Leite