Zero-Field Level-Crossing Effects in a Cascade Process Induced by Highly Saturated Xenon Laser Field

Abstract

Intensity change of spontaneous emission from the lower laser level induced by a linearly polarized laser transition has been studied as a function of magnetic field. By using a zero-field interference effect between magnetic sublevels, the decay times of the upper and lower laser levels can be measured. The intensity change of spontaneous emission has been investigated experimentally in a 3.51 μm (5d₃₃→6p₂₂) and a 5.57 μm (5d₃₄→6p₂₃) xenon laser as a function of polarization directions of the laser radiation and the spontaneous emission, the parameters being the gas pressure and the discharge current. The observed intensity change has two overlapping components of different widths, their ratio being about 1:20. It is found that the narrow component is caused by fourth-order perturbation of the laser field, the coherence among sublevels of the upper laser state being transferred to the lower state.
The observed decay time of the lower laser level is 3.5×10⁻⁸s for the 6p₂₂ level and 2.5×10⁻⁸s for the 6p₂₃ state at a pressure of 13 mTorr. The observed decay time of the upper level is very sensitive to the discharge conditions and takes a value of (3∼8)×10⁻⁷s for the 5d₃₄ level.