For atomic systems under strong influence of electromagnetic fields, the values of Einstein A and B coefficients have been observed to change from those of isolated atoms. However in our previous experiments which demonstrated the changes of A-coefficients, the self absorption of spontaneous emission was very strong and might the experimental result. In order to reduce the absorption drastically so that its effect can be neglected, we conducted a new experiment. In our new experiment, we measured the spontaneous emission from a very short discharge tube where the absorption was less than 4%. We also use a multichannel detector to monitor a number of spontaneous emission lines simultaneously. We observed that, as the incident photon flux increased, the intensity ratio of two spontaneous emission lines from the same upper level decreased. Any possible instrumental effect has been checked and eliminated. Therefore we can conclude that such observed decrement can only due to the change of Einstein A-coefficients.For atomic systems under strong influence of electromagnetic fields, the values of Einstein A and B coefficients have been observed to change from those of isolated atoms. However in our previous experiments which demonstrated the changes of A-coefficients, the self absorption of spontaneous emission was very strong and might the experimental result. In order to reduce the absorption drastically so that its effect can be neglected, we conducted a new experiment. In our new experiment, we measured the spontaneous emission from a very short discharge tube where the absorption was less than 4%. We also use a multichannel detector to monitor a number of spontaneous emission lines simultaneously. We observed that, as the incident photon flux increased, the intensity ratio of two spontaneous emission lines from the same upper level decreased. Any possible instrumental effect has been checked and eliminated. Therefore we can conclude that such observed decrement can only due to the change of Einstein A-coefficients.

Annual Meeting Optical Society of AmericaJan 1, 19930 citations

Comparison of the classical rate and the Einstein coefficient for spontaneous emission in a light-absorbing cavity

Vitaly V. Datsyuk, Saulius Juodkazis, Hiroaki Misawa

The rate of spontaneous electromagnetic emission in a cavity is the normalized output radiation rate in the classical electrodynamics and the Einstein $A$ coefficient in a quantum theory. We reveal the difference and similarity between the quantum and classical rates by calculations of the relative output power of the resonant spontaneous electric-dipole emission as a function of light absorption in a high- $Q$ cavity. We show that the relative resonant output power is equal to the relative width of a morphology-dependent resonance in the spectral dependence of the Einstein $A$ coefficient. The validity of the theory is demonstrated by numerical verification of an experimental result on a microsphere.The rate of spontaneous electromagnetic emission in a cavity is the normalized output radiation rate in the classical electrodynamics and the Einstein $A$ coefficient in a quantum theory. We reveal the difference and similarity between the quantum and classical rates by calculations of the relative output power of the resonant spontaneous electric-dipole emission as a function of light absorption in a high-$Q$ cavity. We show that the relative resonant output power is equal to the relative width of a morphology-dependent resonance in the spectral dependence of the Einstein $A$ coefficient. The validity of the theory is demonstrated by numerical verification of an experimental result on a microsphere.

Physical Review AAug 15, 20054 citations

Spontaneous radiation by a three-level atom in a dissipative medium

Hui W. Cao, Chang-qi Cao

Spontaneous radiation by three-level atoms in a dissipative medium (such as plasma) has been investigated by Langevin equations and the modified Weisskopf-Wigner approximation. General formulae for calculating spontaneous emission coefficients, i.e. Einstein A coefficients, are presented. Numerical calculation shows that the dissipation of plasmas can modify the spontaneous emission coefficients significantly and causes a pit in the coefficient-density curves for relatively low temperature plasmas, and also a pit in the coefficient-temperature curves.Spontaneous radiation by three-level atoms in a dissipative medium (such as plasma) has been investigated by Langevin equations and the modified Weisskopf-Wigner approximation. General formulae for calculating spontaneous emission coefficients, i.e. Einstein A coefficients, are presented. Numerical calculation shows that the dissipation of plasmas can modify the spontaneous emission coefficients significantly and causes a pit in the coefficient-density curves for relatively low temperature plasmas, and also a pit in the coefficient-temperature curves.

Journal of Physics B Atomic Molecular and Optical PhysicsMar 28, 19955 citations

The rate of spontaneous electromagnetic emission in a cavity is the normalized output radiation rate in the classical electrodynamics and the Einstein

A

coefficient in a quantum theory. We reveal the difference and similarity between the quantum and classical rates by calculations of the relative output power of the resonant spontaneous electric-dipole emission as a function of light absorption in a high-

Q

cavity. We show that the relative resonant output power is equal to the relative width of a morphology-dependent resonance in the spectral dependence of the Einstein

A

coefficient. The validity of the theory is demonstrated by numerical verification of an experimental result on a microsphere.