Record Details

Title:
Observation of Reverse Saturable Absorption of an X-ray Laser
Affiliation(s):
EuXFEL staff, Other
Author group:
Instrument HED
Topic:
Scientific area:
Abstract:
A nonlinear absorber in which the excited state absorption is larger than the ground state can undergo a process called reverse saturable absorption. It is a well-known phenomenon in laser physics in the optical regime, but is more difficult to generate in the x-ray regime, where fast nonradiative core electron transitions typically dominate the population kinetics during light matter interactions. Here, we report the first observation of decreasing x-ray transmission in a solid target pumped by intense x-ray free electron laser pulses. The measurement has been made below the $K$-absorption edge of aluminum, and the x-ray intensity ranges are ${10}^{16}-{10}^{17}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$. It has been confirmed by collisional radiative population kinetic calculations, underscoring the fast spectral modulation of the x-ray pulses and charge states relevant to the absorption and transmission of x-ray photons. The processes shown through detailed simulations are consistent with reverse saturable absorption, which would be the first observation of this phenomena in the x-ray regime. These light matter interactions provide a unique opportunity to investigate optical transport properties in the extreme state of matters, as well as affording the potential to regulate ultrafast x-ray free-electron laser pulses.
Imprint:
2017
Journal Information:
Physical Review Letters, 119, 075002 (2017)
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Language(s):
English
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Record created 2017-12-07, last modified 2019-01-30

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