Elisabeth Giacobino

Bistability, self-pulsing and chaos in optical parametric oscillators

SummaryWe consider a degenerate parametric oscillator and show that, when the cavity is detuned both with respect to the pump and with respect to its subharmonic, the system can display bistable or self-pulsing behaviour. Bistability (self-pulsing) requires that the product of the two detuning parameters is positive (negative). In the self-pulsing regime, the system exhibits period doubling and chaos. We generalize our steady-state analysis to the case in which the cavity has a poor finesse for the pump mode.RiassuntoSi considera un oscillatore parametrico degenere e si mostra che, quando la cavità è fuori risonanza sia rispetto alla pompa che rispetto alla sua subarmonica, il sistema può esibire comportamento bistabile o autoimpulsato. Il comportamento bistabile (autoimpulsato) richiede che il prodotto dei due parametri di fuori risonanza sia positivo (negativo). Nel regime autoimpulsato, il sistema mostra raddoppiamento di periodo e caos. Si generalizza lanalisi stazionaria al caso in cui la cavità ha qualità cattiva per il modo di pompa.РезюмеМы рассматриваем вырозденный параметрический осциллятор и показываем, что, когда резонатор находится вне резонанса относительно накачки и относительно субгармоник, тогда система может обнаруживать бистабильное или самопульсирующее поведение. Бистабильность (самопульсирование) требует, чтобы произведение двух параметров расстройки являлось положительным (отрицательным). В режиме самопульсирования система обнаруживает удвоение и хаос. Мы обобщаем наш стационарный анализ на случай, в котором резонатор имеет плохое качество для моды накачки.

Observation of bistability and delayed bifurcation in a triply resonant optical parametric oscillator

We have experimentally studied the various dynamical regimes appearing in an optical parametric oscillator that is simultaneously resonant for the pump, the signal, and the idler modes, and we have observed bistability and instability. When the pump intensity is swept through the static threshold value in the monostable region, we observe that the oscillation is delayed by a time interval that is much larger than the characteristic evolution times of the system. The measurements are in good agreement with the theoretical predictions.

Type-II continuous-wave optical parametric oscillators: oscillation and frequency-tuning characteristics

We detail the oscillation properties of cw type-II optical parametric oscillators (signal and idler modes with orthogonal polarizations). When the signal and idler frequencies are very close, they are shown to have characteristics that are quite different from the well-known type-I optical parametric oscillators. We determine in particular the cavity-length values for which the oscillation occurs and how the frequencies of the output fields vary when one changes this length, the crystal angle, or the temperature. Finally, we determine the influence of the mirror phase shifts on the oscillation characteristics of a linear-cavity OPO.

Squeezing in detuned degenerate optical parametric oscillators

The authors calculate analytically the squeezing spectra of the signal and pump fields in a degenerate optical parametric oscillator for arbitrary values of the detuning parameters. For this purpose they use the recently introduced semi-classical method as well as the standard quantum approach.

Four wave mixing oscillation in a semiconductor microcavity: generation of two correlated polariton populations.

We demonstrate a novel kind of polariton four wave mixing oscillation. Two pump polaritons scatter towards final states that emit two beams of equal intensity, separated both spatially and in polarization with respect to the pumps. The measurement of the intensity fluctuations of the emitted light demonstrates that the final states are strongly correlated.

I Quantum Fluctuations in Optical Systems

Publisher Summary This chapter discusses the quantum fluctuations in optical systems. Quantum fluctuations are present in every measurement. In the measurement device, quantum fluctuations have an effect similar to that of the instrumental noise or thermal fluctuations. The chapter describes the principal experiments that have generated light with reduced quantum fluctuations, and the applications of such light. Straightforward calculations involving squeezed fields help to explain the experimental results. The squeezed fields are treated in the framework of the semiclassical linear input output theory, which models the quantum fluctuations by classical random fields. The standard representations of quantum optics are used to treat the quantum fluctuations and properties of the squeezed states, and to study the ideal parametric interaction Hamiltonian in detail. The chapter also discusses the quantum properties of the parametric generation in an optical cavity, including the two regimes below and above the oscillation threshold.

Twin polaritons in semiconductor microcavities

The quantum correlations between the beams generated by polariton pair scattering in a semiconductor microcavity above the parametric oscillation threshold are computed analytically. The influence of various parameters, including the cavity-exciton detuning, the intensity mismatch between the signal and idler beams, and the amount of spurious noise, is analyzed. We show that very strong quantum correlations between the signal and idler polaritons can be achieved. However, the quantum effects in the outgoing light fields are strongly reduced due to the large mismatch in the coupling of the signal and idler polaritons to the external photons.

Spatial quantum noise of semiconductor lasers

The transverse distribution of intensity noise in the far field of semiconductor lasers has been experimentally studied. For a single-mode edge-emitting laser, it has been found that a large amount of noise is present in higher-order nonlasing transverse modes parallel to the diode junction. In the case of a spatially multimode vertical-cavity surface-emitting laser, each mode exhibits a large noise, but these noises show strong anticorrelations.

SPATIAL DISTRIBUTION OF THE INTENSITY NOISE OF A VERTICAL-CAVITY SURFACE-EMITTING SEMICONDUCTOR LASER

We studied anticorrelated quantum fluctuations between the TEM(00) and the TEM(01) transverse modes of a vertical-cavity surface-emitting semiconductor laser by measuring the transverse spatial distribution of the laser beam intensity noise. Our experimental results are found to be in good agreement with the predictions of a phenomenological model that accounts for quantum correlations between transverse modes in a light beam.

Atomic number fluctuations in a falling cold atom cloud

We evaluate the effective number of atoms in experiments where a probe laser beam with a Gaussian transverse profile passes through an atomic medium consisting of a cold atom cloud released from a magneto-optical trap. Considering the case where the initial distribution is a Gaussian function of position and of velocity, we give a quantitative description of the time variation of the effective number while the cloud is exploding and falling. We discuss the two cases where the effective number is defined from the linear and nonlinear phase shifts, respectively. We also evaluate the fluctuations of the effective atomic number by calculating their correlation functions and the associated noise spectra. Finally, we estimate the effect of these fluctuations on experiments where the probe beam passes through a cavity containing the atomic cloud.