Nonlinear dynamics of a two-photon Fabry–Pérot laser

Abstract The steady-state emission, stability and temporal dynamics of a single-mode two-photon laser with a Fabry–Perot cavity is investigated and compared with that of a ring-cavity laser. It is found that the Fabry–Perot cavity makes the laser less efficient than the ring cavity because of spatial hole burning, but the domain of stability is larger for the Fabry–Perot laser. The intensity and phase dynamics are numerically investigated and distinctive features are found in the phase dynamics as compared with one-photon lasers.

Type-II intermittency in a cascade laser model

Low frequencies noise effects on behaviour of Sparus aurata juveniles

Human activities in the oceans, such as marine traffic and Deep Sea Mining (DSM), are increasing in the last years (Ross 2005; Calvo et al 2016). Underwater noise in the oceans, especially at lower frequencies, is mainly produced by marine traffic and DSM could increase this noise in the next future. Marine Strategy Framework Directive promotes the achievement of a good quality environmental status and aims to monitor “continuous low frequency sound” trend in the ambient noise level within the 1/3 octave bands centred at 63 and 125 Hz. The aim of this study is to evaluate the behavioural changes of Sparus aurata juveniles exposed to a four different acoustic signals in a tank. The emitted s…

Domain wall dynamics in an optical Kerr cavity

An anisotropic (dichroic) optical cavity containing a self-focusing Kerr medium is shown to display a bifurcation between static --Ising-- and moving --Bloch-- domain walls, the so-called nonequilibrium Ising-Bloch transition (NIB). Bloch walls can show regular or irregular temporal behaviour, in particular, bursting and spiking. These phenomena are interpreted in terms of the spatio-temporal dynamics of the extended patterns connected by the wall, which display complex dynamical behaviour as well. Domain wall interaction, including the formation of bound states is also addressed.

Types I and II intermittencies in a cascade laser model

Abstract We report on types I and II intermittencies found in a cascade laser model. A continuous transition from one to another type of intermittency, which involves the coexistence of both types of laminar phases within the same time series, is found. Type II intermittency has special characteristics such as its origin at a frequency locked two-torus. When frequency unlocked this torus bifurcates to a three-torus, further giving rise to a type II intermittent like behaviour with new features during the laminar phases.

Class-B two-photon Fabry–Pérot laser

Abstract We study the stationary operation and stability properties of a class-B two-photon Fabry–Perot laser. We show that, differently from the one-photon laser, the intensity emitted by the two-photon laser is larger in a Fabry–Perot than in a ring cavity. The lasing solution loses stability through a subcritical Hopf bifurcation, as it occurs in the unidirectional ring laser. The stability domain in the parameter space is larger in the Fabry–Perot than in the ring cavity configuration.

The effect of low frequency noise on the behaviour of juvenile Sparus aurata.

[EN] Anthropogenic activities are causing increased noise levels in the marine environment. To date, few studies have been undertaken to investigate the effects of different noise frequencies on the behaviour of juvenile fish. In this study, the behavioural changes of juvenile gilthead seabream (Sparus aurata) are evaluated when exposed to white noise filtered in third-octave bands centred at 63, 125, 500, and 1000 Hz (sound pressure level, 140-150 dB re 1 mu& x3a1;a) for 7 h. The group dispersion, motility, and swimming height of the fish were analysed before and during the acoustic emission. Dispersion of the fish was found to reduce immediately upon application of low frequency sound (63…

EFFECT OF SUBMARINE ACOUSTIC NOISE IN JUVENILE SEA BREAM (SPARUS AURATA) AND MUSSELS (MYTILUS GALLOPROVINCIALIS)

The earth’ resources are running out, the population will increase and further sources will be needed. These, were found in the deep ocean. To date the mining activities (Deep Sea Mining, DSM) they have not started. One impact of DSM could be underwater noise. Considering the noise frequencies of anthropic activities in the ocean, and the European directive on underwater noise control, we stressed the animals with four acoustic 1/3 band noises around: 63 Hz, 125 Hz, 500 Hz, 1kHz. We study the effects on Sparus aurata juveniles, and on Mytilus galloprovincialis. We will analyse behavioural., molecular and biochemical responses Los recursos de la tierra se están agotando, la población aumenta…

Anthropogenic noise: the behavioural responses of Sparus aurata juveniles as the basis for a numerical model.

Underwater noise is mainly produced by anthropogenic activities and has increased in recent years. The Marine Strategy Framework Directive aims to monitor “continuous low frequency sound” trends in ambient noise in particular at 1/3rd octave bands centered at 63 and 125 Hz. The aim of this work is to evaluate the possibility of using the results of Sparus aurata juvenile’s behavior for parameterizing a numerical model of the fish behavior. The fishes were stressed with white noise filtered with a band pass filter at 1/3 octave band centered respectively at 63 Hz, 125 Hz, 500 Hz, and 1 kHz (SPL: 140-150 dB re 1µPa). We performed three test replicas for the control (without any sound emission…

One- and two-photon lasers with injected signal in a high-Q fabry-Pérot cavity

Explicit models are derived for good cavity one- and two-photon lasers with an injected signal in a Fabry-Perot cavity. The steady solutions and their stability properties are obtained analytically and compared with the corresponding ring cavity model ones. Only quantitative differences between both types of cavities are found. In particular we show that (i) the Fabry-Perot cavity reduces significantly the domain of self-pulsing with respect to the ring cavity, and for the two-photon laser case (ii) larger output can be extracted from a Fabry-Perot cavity than from a ring cavity under certain conditions, something impossible in free-running lasers. We conclude that ring cavity models are se…