Journal of the Optical Society of America B

Inhomogeneous broadening-dependent spectral features in a four-level atomic system

W. H. Burkett, Yongqing Li, Min Xiao

Published Feb 1, 2000• 4 citations

Abstract

New spectral features in an inhomogeneously broadened N-type four-level atomic system are analyzed and discussed. The atomic-level scheme uses an incoherent pumping rate in place of the incoherent recycling pump. We show that the gain profile includes an extra dip that appears only in the Doppler-broadened case. The dependence of this feature on various parameters, as well as consequences for the dispersion, are explored theoretically. For certain combinations of temperature and incoherent pump rate, this gain is shown to be independent of temperature fluctuations.

DOI: 10.1364/josab.17.000293

Related papers

Gain without inversion in a V-type system with low coherence decay rate for the upper levels

Dipankar Bhattacharyya, Biswajit Ray, Pradip Narayan Ghosh

Inversionless gain is observed in a V-type inhomogeneously broadened system without introducing any incoherent pumping and only by changing the collisional dephasing decay rate. In this system sub-Doppler linewidth is achieved with off-resonance pump detuning.

arXiv:physics/0405079May 15, 20040 citations

Role of incoherent pumping scheme on gain without population inversion in four-level systems

Bibhas Kumar Dutta, P.K. Mahapatra

We have studied gain without population inversion in two similar four-level systems by employing semiclassical density-matrix formalism. If the incoherent pumping process is not taken into account, both systems can be visualized as an ideal V-type system. Along with the application of strong pump and weak probe fields, an incoherent pump field is added to each of the systems in a different configuration. It has been shown that the different mechanisms of application of an incoherent pump to the system can appreciably change the population difference between the energy levels of the strongly driven transition and results in the evolution of inversionless gain either at the line center or at the sidebands on probe detuning. The effect of inhomogeneous broadening on the probe gain has also been studied.

Physica ScriptaJan 23, 200814 citations

Lasing without inversion with a fluctuating pump: Gain dependence on pump noise and frequency

Gautam Vemuri, Donald M. Wood

Recently it was reported that replacing an incoherent pumping mechanism by a spectrally colored (partially coherent) pump can lead to significant gain enhancement in lasing without inversion schemes [Phys. Rev. A 48, R4055 (1993)]. We extend that study further by considering the effects of the noise parameters (strength and bandwidth) of the pump on the gain in two types of three-level atomic energy-level schemes---the ladder and the \ensuremath{\Lambda} models. The calculations presented in this paper show a way to continuously ``tune'' the bandwidth of the pump and make a direct comparison between the gain obtained for coherent, incoherent, and partially coherent pumping. We find that for a given set of atom-field parameters, the gain for coherent pumping is larger than for incoherent pumping, and that maximum gain is obtained for a partially coherent pump. Increasing the strength of the noise also leads to an increase in the gain. The frequency of the colored pump plays a critical role in determining the maximum gain that can be obtained.

Physical Review AJul 1, 199417 citations

Physical origin of the gain in a model of a laser without inversion

Heide Doss, Lorenzo M. Narducci, Marlan O. Scully +2 more

We consider a four-level atomic system with a degenerate or quasidegenerate ground-state doublet and two excited states. One of the upper levels is coupled to the ground doublet by a coherent field of variable strength, which we refer to as the Raman field, whose role is to create atomic coherence between the driven atomic states. The other higher lying state is coupled to the ground states when laser action develops. This model includes an incoherent pump mechanism to create some population in the top lasing state. In appropriate conditions, for the incoherent pump rate and the Raman field strength, the absorption profile of the laser transition develops gain features. We discuss the physical origin of this gain which we find to be the consequence of a population inversion between dressed atomic states. It is interesting to compare the results of this analysis with a similar study of a three-level lambda system which was previously recognized to yield lasing without inversion.1 In this case the appearance of gain can be attributed to the induced atomic coherence.

Annual Meeting Optical Society of AmericaJan 1, 19910 citations

Influence of Doppler broadening and spontaneously generated coherence on propagation effect in a quasi lambda-type four-level system

Zhongbo Liu, Ying Liang, Kening Jia +1 more

In this paper we study influences of Doppler broadening, spontaneously generated coherence, and other system parameters on propagation effect in a quasi lambda-type four-level atomic system. It is shown that when the Doppler broadening is present, generally speaking, the values of gain and intensity of lasing without inversion (i.e. the probe field) in the co-propagating probe and driving fields case are much larger than those in the counter-propagating case; considerably larger gain and intensity of lasing without inversion than those without the Doppler broadening can be obtained by choosing appropriate values of the Doppler broadening width and spontaneously generated coherence strength. The gain and intensity of lasing without inversion increase with the increase of spontaneously generated coherence strength; when spontaneously generated coherence is present, much larger gain and intensity of lasing without inversion than those in the case without spontaneously generated coherence can be obtained. Choosing suitable values of the probe detuning, Rabi frequencies of the driving and pump fields at the entrance of the medium also can remarkably enhance the gain and intensity of lasing without inversion.

Chinese Physics BFeb 1, 20125 citations

Modulation of atomic exit and injection rates on the phase-dependent gain without inversion in a Doppler broadened open four-level system

Zhongbo Liu, Kening Jia, Ying Liang +2 more

It is shown that in a Doppler broadened open N-type four-level atomic system with spontaneously generated coherence (SGC), the gain without inversion (GWI) is very sensitive to the variation of the relative phase between the probe field and the driving field; the atomic exit rate ( R 0 ) and the ratio ( S ) of the atomic injection rates have a considerable modulation effect on the phase-dependent GWI. GWI first increases and then decreases with Ro increasing; in a certain value range of S , GWI increases monotonically with S increasing; by adjusting the values of R 0 and S , in an open system a much larger GWI can be obtained than in the corresponding closed system [ 2011 Phys. Rev. A 83 043805 ]. The modulation effects of R 0 and S on the phase-dependent GWI in the case with the counter-propagating probe and driving fields are stronger than those in the co-propagating case, GWI in the co-propagating case is much larger than that in the counter-propagating case.

Chinese Physics BJun 1, 20122 citations