Photonic Switching Due To Local Field Effects

It is well known that quantum coherence and interference in atomic systems can lead to lots of interesting optical phenomena such as coherent population trapping, electromagnetically induced transparency,index enhancement without absorption,lasing without a population inversion,etc.These new effects have great potential for the control of the coherence properties of a medium,the production of high frequency lasers.In all of these studies it is assumed that the atomic density is small such that local field effects are unimportant.But as the effect takes place in the vicinity of an atomic resonance,large nonlinearities are to be expected and need to be taken into account for potential applications of high-index materials.Aaron S.Manka,Jonathan P.Dowling and Charles M.Bowden have studied the influence of near dipole-dipole(NDD) interactions by taking into account the full nonlinear response of the atoms.They predict the piezophotonic switching due to local field effects in a coherently prepared medium of three-level A system.The gain curve can be made to switch suddenly from high loss to high inversionless gain as a sensitive function of the atomic density.They dub this process piezophotonic effect:a pressure sensitive sudden amplification of light.In this paper,we have studies new phenomena of piezophotonic switching in the three-level V system.The results indicate that as the density is further increased in the regime of moderate E,there is a threshold value of density where the absorption and dispersion curve to become one of large gain.By varying the density about the threshold value,this effect could be exploited in the form of an optical switch.We predict the existence of a range of frequencies where the gain and the index of refraction are simultaneously very large after the flip.