Abstract
We show that the intensity of self-seeded lasing at 391 nm, assigned to the emission, is enhanced by 2 orders of magnitude by modulating in time the polarization of an intense ultrashort near-IR (40 fs, 800 nm) laser pulse with which is irradiated. We find that this dramatic enhancement of the 391 nm lasing is sensitive to the temporal variation of the polarization state within the laser pulse while the intensity of the spontaneous fluorescence emission at 391 nm is kept constant when the polarization state varies. We conclude that a postionization multiple-state coupling, through which the population can be transferred from the state of to the first electronically excited state, leads to the depletion of the population in the state, and consequently, to the population inversion between the state and the state.
- Received 23 September 2018
DOI:https://doi.org/10.1103/PhysRevLett.122.013202
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