P. Anantha Lakshmi

Effect of cooperativity on squeezing in resonance fluorescence

Squeezing characteristics of the radiation field produced by a collective system of atoms driven by a coherent field are calculated. The collective behavior is found to affect the squeezing behavior considerably.

Spectral fluctuation characterization of random matrix ensembles through wavelets

A recently developed wavelet based approach is employed to characterize the scaling behaviour of spectral fluctuations of random matrix ensembles, as well as complex atomic systems. Our study clearly reveals anti-persistent behaviour and supports the Fourier power spectral analysis. It also finds evidence for multi-fractal nature in the atomic spectra. The multi-resolution and localization nature of the discrete wavelets ideally characterizes the fluctuations in these time series, some of which are not stationary.

MODE HOPPING IN EXTERNAL-CAVITY DIODE LASERS

Mode hopping in external-cavity AlGaAs diode lasers has been studied experimentally. Its dependence on the amount of feedback and the external-cavity round-trip phase has been studied. The results are compared with the predictions of potential well models. As the feedback is increased the results differ considerably from this theory. A qualitative treatment is also presented.

Nonlinear magneto-optical rotation in calcium - theory and experiment

Theoretical and experimental studies of nonlinear magneto-optical rotation in the principal series of calcium are reported. These are believed to be the first experiments on high magnetic field Faraday rotation (defined as achieving rotation angles of the order of or more) in which the nonlinear optical regime has been entered by using laser fields. The present theory is valid both in the linear and nonlinear domains and our theoretical predictions which take into account propagation effects agree very well with experimental results over the entire range of laser strengths.

Scaling laws for atomic compressibility

We consider the concept of atomic pressure for atoms subjected to quantum confinement. New scaling rules are introduced which allow the compressibility to be expressed as the product of two factors. The first is a term independent of compression, which varies widely from atom to atom, but can be computed in the free atom limit. The second is a term expressed in dimensionless variables, whose dependence on compression is in general nonlinear and may exhibit discontinuities. However, it is shown not to vary much from one atom to another and to follow general rules which are easily understood. We have performed fully relativistic ab initio calculations to illustrate these general rules of atomic compressibility, and we characterize the variation of atomic compressibility for both soft and hard atoms.

Cooperative effects in optical double resonance

A theory of optical double resonance which takes into account the cooperative interactions among atoms is formulated. The analytical result for the double resonance spectra in the conventional situation when the probe field is weak, is given. The changes in the nature of the spectra as one sweeps from cooperative to single atom branch are discussed. The cooperative interaction is shown to reduce considerably the asymmetry of the Autler-Townes doublet.