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Role of wavelength in photocarrier absorption and plasma formation threshold under excitation of dielectrics by high-intensity laser field tunable from visible to mid-IR
The development of high power mid-IR laser applications requires a study on laser induced damage threshold (LIDT) in the mid-IR. In this paper we have measured the wavelength dependence of the plasma formation threshold (PFT) that is a LIDT precursor. In order to interpret the observed trends numeri...
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Published in: | Scientific reports 2020-08, Vol.10 (1), p.14007-14007, Article 14007 |
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Main Authors: | , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The development of high power mid-IR laser applications requires a study on laser induced damage threshold (LIDT) in the mid-IR. In this paper we have measured the wavelength dependence of the plasma formation threshold (PFT) that is a LIDT precursor. In order to interpret the observed trends numerically, a model describing the laser induced electron dynamics, based on multiple rate equations, has been developed. We show both theoretically and experimentally that PFT at mid-IR wavelengths is controlled by a transition from weak- to strong-field regime of free carrier absorption. In the case of MgF
2
this transition occurs around 3–4
μ
m corresponding to the region of the lowermost PFT. The region of the uppermost PFT is reached around 1
μ
m and is governed by an interplay of photoionization and weak-field free carrier absorption which manifests itself in both MgF
2
and SiO
2
. The PFT observed in considered materials exhibits a universal dependence on the excitation wavelength in dielectrics. Thus, the presented results pave the route towards efficient and controllable laser-induced material modifications and should be of direct interest to laser researchers and application engineers for prevention of laser-induced damage of optical components in high-intensity mid-IR laser systems. |
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ISSN: | 2045-2322 2045-2322 |
DOI: | 10.1038/s41598-020-70862-w |