Non-linear properties of strongly pumped lasers (original) (raw)
Related papers
Influence of light polarization on the dynamics of optically pumped lasers
Physical Review A, 1990
The dynamic behavior of a coherently pumped ring laser with a homogeneously broadened four-level medium is analyzed theoretically, considering linearly polarized pump and generated laser beams. The laser is shown to be much more stable when these polarizations are parallel than when they are orthogonal. In the latter case the instability pump threshold can be as low as four times the first laser threshold, and the laser dynamics shows Lorenz-type features. Recent experimental studies of self-pulsing in an optically pumped FIR single-mode ammonia laser showed for the first time Lorenz-like behavior in the real world. ' The theoretical interpretation of these results raises conceptual difficulties, however, since the FIR laser experiments are a priori more complicated than the simple twolevel homogeneously broadened medium interacting with a single mode of a unidirectional ring cavity, which is considered in the Lorenz-Haken model. Recently, we have shown that a more appropriate Doppler-broadened threelevel laser model can explain the appearance of Lorenzlike dynamics in an optically-pumped
Threshold and nonlinear behavior of lasers of Λ and V configurations
Physical Review A, 1998
Dynamic properties of closed three level laser systems are investigated. Two schemes of pumping -Λ and V -are considered. It is shown that the non-linear behavior of the photon number as a function of pump both near and far above threshold is crucially different for these two configurations. In particular, it is found that in the high pump regime laser can turn off in a phase-transition-like manner in both Λ and V schemes. *
Dynamics of coherently pumped lasers with linearly polarized pump and generated fields
Physical Review A, 1993
The inhuence of light polarization on the dynamics of an optically pumped single-mode laser with a homogeneously broadened four-level medium is theoretically investigated in detail. Pump and laser fields with either parallel or crossed linear polarizations are considered, as are typical in far-infraredlaser experiments. Numerical simulations reveal dramatically different dynamic behaviors for these two polarization configurations. The analysis of the model equations allows us to find the physical origin of both behaviors. In particular, the crossed-polarization configuration is shown to be effective in decoupling the pump and laser fields, thus allowing for the appearance of Lorenz-type dynamics. PACS number(s): 42.60.Mi, 42.50.Lc, 42.55.f
Nonlinear effects in optical pumping of a cold and slow atomic beam
Physical Review A, 2015
By photoionizing hyperfine (HF) levels of the Cs state 6 2 P 3/2 in a slow and cold atom beam, we find how their population depends on the excitation laser power. The long time (around 180 μs) spent by the slow atoms inside the resonant laser beam is large enough to enable exploration of a unique atom-light interaction regime heavily affected by time-dependent optical pumping. We demonstrate that, under such conditions, the onset of nonlinear effects in the population dynamics and optical pumping occurs at excitation laser intensities much smaller than the conventional respective saturation values. The evolution of population within the HF structure is calculated by numerical integration of the multilevel optical Bloch equations. The agreement between numerical results and experiment outcomes is excellent. All main features in the experimental findings are explained by the occurrence of "dark" and "bright" resonances leading to power-dependent branching coefficients.
The dynamics of optically pumped molecular lasers. On its relation with the Lorenz-Haken model
Quantum and Semiclassical Optics, 1997
In this paper we review the work on dynamical instabilities in optically pumped molecular lasers (OPLs) that has been carried out during the last 15 years. The main purpose of this review article is to survey and extend the authors' work on optically pumped molecular lasers and to place it in context with other research done in this area, without being a comprehensive review of all previous work done on this topic. In particular, we concentrate on the theoretical interpretation of the Lorenz dynamics observed in the far-infrared ammonia laser by reviewing the results obtained with different models of OPLs. New results corresponding to the dynamics obtained with the Doppler-broadened OPL model are also given. In particular the influence of pump detuning is considered and we also provide a characterization of the chaotic dynamics that definitively clarifies its Lorenz character. Finally a critical account of the present understanding of the far-infrared ammonia laser experiments is given.
Journal of the Optical Society of America B, 1999
We study theoretically the dynamic behavior of a JЈ ϭ 1 → JЉ ϭ 0 laser (J is the angular momentum quantum number) optically pumped by means of a linearly polarized coherent field (coupled to an adjacent transition J ϭ 0 → JЈ ϭ 1) when the pump field polarization is rotated at a constant angular velocity ⍀ and the laser field polarization either is fixed by the cavity or is free (isotropic cavity). Because of a strong pumpinduced gain anisotropy, the dynamic behavior is completely different in each case. In the case of fixed laser field polarization, rich amplitude dynamics, which depend on the pump field strength, are found. At slow modulation frequencies (with respect to the molecular and the cavity relaxation rates), the system does not always follow the sequence of stationary and dynamic solutions that correspond to the autonomous laser as a function of the relative orientation angle between the polarizations of the pump and the laser fields. Phenomena such as delayed switching and suppression of chaos and stabilization of unstable steady states are found. In the case of an isotropic cavity, the pump field vector rotation is transferred to the laser field vector and amplitude unstable regimes are also strongly inhibited.
Mode selectivity and stability of continuously pumped atom lasers
Physical Review A, 2003
A semiclassical, multimode model of a continuously pumped atom laser is presented. For a spatially independent coupling process it is found that the system is unstable below a critical scattering length. As large atomic interactions will increase the phase diffusion of the lasing mode, it is desirable to obtain a stable atom laser with low nonlinearity. It is shown that spatially dependent pumping stabilizes the atom laser to a finite number of modes, and can induce single-mode operation.
International Journal of Infrared and Millimeter Waves, 1980
Within the framework of a semiclassical description, Maxwell's equations coupled to the density matrix equations, the serial three-wave problem comprised of a strong pump (P(32) 9 ~m CO 2 band) and two emission waves (50 Dm and 66 ~m) is studied and compared with experiments in a single pass amplifier configuration. The overall evolution is shown to be consistent with emitted waves evolving as separate stimulated Raman waves, with a chirp on the FIR caused by AC Stark shifts by the pump, and with orientational effects leading to a preferential polarization. No evidence for three-photon interactions is indicated at the intensity levels available in the experiments.
2007
1 INTRODUCTION The dynamics of a single mode CO=laser has been investigated by performing low frequency modulation of either the cavity toss parameter or the pump parameter. Delayed bifurcations/l/ are observed only in the second case. This phenomenor. is related to a dynamic stabilization of the zero state intensity which becomes unstable for a pump value larger than the stationary value. In contrast, when we perform a linear sweep on the cavity loss parameter we 03serve a dynamical hysteresis depending on the modulation depth and on the sweep frequency but without time delay /2/. This difference between pump and loss modulation can be explained by considering a fourlevel molecular model which takes into account the coupling between the two active resonant levels of the P(20) transition and the other rotational levels of the vibrational bands (00'1 and 10'0) to which they belong /3/ .