The change of optical and structural properties of MgO by the exposition to laser pulse irradiation

Abstract

Interaction processes are studied of impulse laser irradiation (λ = 1.06 μm) with the MgO monocrystal. The structural crystal transformations after the exposure are studied by the X‐ray structural analysis (XRA), time‐of‐flight cathodoluminescence (10−8 s), and other optical techniques. The process of the crystal defect formation on the whole volume of the sample (effect of the side opposite to the irradiated one) is ascertained to the exposure of the impulse laser irradiation onto the MgO surface in the melting regime. The laser impulse heating of the MgO surface leads to the process of recrystallization when a material is divided into blocks whose dimensions are much less than the ones of the outcoming (non‐irradiated) samples; at the same time a growth of microstrains is observed in the whole volume of the samples. Formation and transformation of point structural defects occur side by side with density dislocation growth ≈︁ 1011 cm−2. Cathodoluminescence (CL) measurements show changes in the spectrum (2.4 to 2.6), (3.0 to 3.1), (3.3 to 3.4) eV caused by laser irradiation which may be explained by point‐defect formation in MgO. The results obtained allow to understand the process of the defect formation by impulse laser onto the MgO crystal surface.