Physical Review A

Phase and amplitude correlations induced by the switch-on chirp of a detuned laser

Sergio Ciuchi, Maxi San Miguel, N. B. Abraham, FERDINANDO DE PASQUALE

Published Dec 1, 1991• 11 citations

Abstract

The correlations of the fluctuations of the electric field are studied for a simple model of the buildup from spontaneous-emission noise of the output of a single mode of a laser cavity. Results for when the laser cavity is detuned with respect to the center frequency of the gain medium are compared with the case in which the cavity is resonantly tuned. Resonantly tuned lasers display transient phase and amplitude correlations with a peak at the time that the evolving amplitude departs from the neighborhood of the origin in the complex plane of the amplitude where phase diffusion dominates. Deterministic frequency chirps during the switch-on of a detuned laser delay and significantly strengthen the transient correlation of phase and intensity fluctuations when the detuning is sufficiently large compared with the strength of the noise. In this case the peak in the correlations is related to the anomalous intensity fluctuations characteristic of transient switching.

DOI: 10.1103/physreva.44.7657

Related papers

The noise fluxes produced by the degree of first-order temporal coherence in a single mode class-A laser amplifier

S. Kiashemshaki, J. Jahanpanah

The noise feature of a single mode class-A laser is investigated in the presence (amplifier) and absence (free-running) of an input signal. The Maxwell-Bloch equations of motion have been solved after adding the cavity Langevin force to calculate fluctuations that imposed to the atomic population inversion and the amplitude and phase of cavity electric field. The correlation function of these fluctuations is then used to derive the spontaneous emission, amplitude, and phase noise fluxes in the below and above-threshold states. The bandwidth of noise fluxes is not only adjusted by the amplitude and frequency detuning of input signal, but also by the laser pumping and cavity damping rates. On the other hand, the degree of first-order temporal coherence (DFOTC) is turned out as the correlation function of the amplitude fluctuation so that its Fourier transform led to the amplitude noise flux. The coherence time plays a dual role in order that it is equal to the damping rate invers of DFOTC and at the same time has an uncertainty relation with the bandwidth of amplitude noise flux. Finally, the flux conservation requires a balance between the input pumping noise flux and the output amplitude and spontaneous emission noise fluxes.

arXiv:1912.01485Dec 3, 20190 citations

Variance and spectra of fluorescence-intensity fluctuations from two-level atoms in a phase-diffusing field

M. H. Anderson, R. D. Jones, J. Cooper +4 more

We have measured the variance in fluorescence intensity and the spectrum of those fluctuations for two-level atoms in a phase-diffusing laser field. We compare our results with recent theoretical predictions that have been extended to include the effects of Doppler broadening and spatial variation of the laser intensity. Our study includes the effects of laser power, bandwidth, and shape (Lorentzian and non-Lorentzian) of the laser spectrum. At lower laser intensities, our measured variances versus detuning are in quantitative agreement with the theoretical predictions. At intensities above saturation, the variance is sensitive to inhomogeneities in the distribution of laser intensity in the interaction region, and only qualitative agreement is achieved. Asymmetries in the variance versus detuning resulting from correlated amplitude and phase noise have been observed. Spectra of the phase-noise-induced fluorescence-intensity fluctuations are shown to contain contributions from transients excited by the phase noise and are more sensitive to artifacts in the noise modulation process than the intensity spectrum of the laser field itself.

Physical Review ADec 1, 199032 citations

Theory of resonance fluorescence in a fluctuating laser field

W. Vogel, D.‐G. Welsch, K. Wódkiewicz

A method of calculation of multiple-time correlation functions of the resonance fluorescence light from a two-level atom driven by a realistic laser field with phase and amplitude fluctuations is developed. Both kinds of fluctuations are assumed to be Gaussian. The phase fluctuations are treated in the phase-diffusion model. The averaging over the amplitude fluctuations can be performed in a closed way when the relative mean-square amplitude fluctuation is small compared with the ratio of the amplitude correlation decay rate to the characteristic atomic relaxation rate. There is no restriction to Markovian amplitude fluctuations. Arbitrary values for the mean Rabi frequency are allowed. Results are presented for the intensity, the intensity correlation function, and the spectrum of the fluorescent light. It is shown that even in the case when the relative strength of the amplitude fluctuations is small, significant effects can occur due to the finite correlation length of the fluctuations. The results for fast amplitude correlation decay correspond to the situation without amplitude fluctuations. When the correlation time of the amplitude fluctuations becomes comparable with the atomic relaxation times, the Rabi oscillations of the intensity and the intensity correlation function are nearly washed out, and non-Lorentzian line shapes for the side peaks in the spectrum are observed. It is found that the ratio of the heights of the central peak to the side peak increases with increasing correlation time.

Physical Review ASep 1, 198320 citations

Balance Between Noise Fluxes in Free-Running Single-Mode Class-A Lasers

Jafar Jahanpanah, Azam Soleimani, Fatemeh Shavandi

The fluctuation effect of laser pumping rate on the output noise fluxes of class-A lasers is investigated. The method is based on the role of cavity Langevin force as a fluctuating force in the absence of the atomic population inversion and dipole moment Langevin forces. The temporal fluctuations induced to the phase and amplitude of the cavity electric field and the atomic population inversion are calculated in both below and above threshold states. Our aim is to derive correlation functions for the fluctuating variables of the cavity electric field and the atomic population inversion to determine the noise fluxes emerging from the cavity mirrors and measured by an optical detector and those radiated in the form of a spontaneous emission in all spatial directions. We introduce a heuristic conservation relation that connects the noise flux generated by the laser pumping system with those distributed among the laser variables. Finally, the results are confirmed by demonstrating the energy conservation law.

arXiv:1211.7107IEEE Journal of Quantum ElectronicsJul 28, 20129 citations

Near threshold buildup times of individual modes in a multimode short-cavity dye laser

Steven E. Hodges, W. Gadomski, M. G. Raymer

A short-cavity dye laser has been constructed to study fluctuations arising from quantum noise and mode coupling in multimode systems. Typical dye lasers (i.e., long-cavity) have been found to have cw dynamics that are dominated by coherent wave mixing effects.1 The quantum noise in these lasers also manifests itself as a variance in the buildup times of the laser light intensity. Buildup times of singlemode long-cavity lasers have been studied.2 The relative importance of quantum noise is enhanced in short cavities making the turn-on transient the dominant feature in the laser light fluctuations. We have measured the turn-on transient of individual modes from a multimode short-cavity dye laser following sudden turn-on of the pump power. The shortness of the cavity has the effect of making the decay times of the intracavity field and the molecular population similar. The observed buildup and rise times are compared with those predicted by a semiclassical multimode laser theory with stochastic noise added for several pump rates. Moreover, semiregular oscillations of the total intensity have been observed to occur in short bursts separating intervals of nearly constant cw laser output.

Annual Meeting Optical Society of AmericaJan 1, 19910 citations

Frequency dependence of laser light fluctuations

Surendra Singh, Stephen R. Friberg, L. Mandeļ

The equations of motion for an inhomogeneously broadened laser operating off resonance in the neighborhood of threshold are solved. It is shown that the effects of detuning cannot be described just by a frequency-dependent laser pump parameter, but that the laser characteristics are modified in other ways also. The relative intensity fluctuations and the correlation time of the laser are calculated as a function of mean intensity and frequency, and it is shown that both are affected by detuning. These theoretical conclusions are then confirmed quantitatively by direct photoelectric counting and two-time correlation measurements of a He:Ne laser.

Physical Review AJan 1, 198313 citations