Diffusion of resonance radiation in optically saturated sodium vapour

Investigation of Radiation Trapping in Atomic Vapour Excited by Weak Resonant Laser Pulses

“…3. The statistical model confirms again the effect predicted by the numerical and analytic models [24][25][26], and the observations made earlier [27]. At the center of the cell, the excitation is slightly weaker, because the laser pulse intensity decreases due to the absorption in the cell.…”

“…Then the concentration of excited atoms decreases, however, due to the optical bleaching this decrease is similar to the natural decay. A similar behavior of the Na(3P) atoms was already modeled by means of other approaches [24][25][26], and was also confirmed experimentally [28,29]. The evolution of concentration of the excited atoms looks differently at the end of the cell, where the excitation is negligible.…”

“…Due to the strong excitation, the saturation of the resonance transition can occur. Such a case has been investigated intensively within the last decade by several authors using numerical [24], analytic [25][26][27] and experimental methods [27][28][29]. For the strong excitation the Holstein-Biberman equation should be modified.…”

“…It was stated [24] that for the pulsed excitation the concentration of excited atoms can decrease much faster than for the weak excitation because the saturation of the optical transition leads to the transparency of the medium for the resonant photons. It causes also a faster evolution of the fluorescence signal than that for the weak excitation.…”

Investigations of Electron Impact Induced Excitations from 3P to Higher Lying Levels of Sodium

“…A saturation of the optical transition, which occurs for such circumstances, leads to substantial reduction of the absorption coefficient, the phenomenon known as the optical bleaching. As we stated elsewhere [31], due to this effect the decay of the excited atoms is faster for the strong excitation than for a weak one. In this experiment resonant radiation power density was about 80 kW/cm2 with the spectral linewidth about 0.01 nm, then the 3S-3P transition was fully saturated within the whole laser pulse [32,33], i.e.…”