Abstract
The nodular defect shape and the laser incidence angle have a dramatic
impact on the spatial distribution of light intensification within the
nodule as well as how the laser light is drained from the defect.
Nodular defect geometries unique to ion beam sputtering, ion-assisted
deposition, and electron-beam (e-beam) deposition, respectively, are
modeled in this parametric study over a wide range of nodular
inclusion diameters and layer count for optical interference mirror
coatings constructed with quarter-wave thicknesses and capped with a
half wave of the low index material. It was found for hafnia (
n
=
1.9
) and silica (
n
=
1.45
) multilayer mirrors that the light
intensification in nodular defects with a
C
factor of 8, typical of e-beam
deposited coatings deposited with a wide range of deposition angles,
was maximized for a 24-layer design. For intermediate size inclusion
diameters, increasing the layer count for normal incidence multilayer
mirrors reduced the light intensification within the nodular defect. A
second parametric study explored the impact of the nodule shape on the
light intensification for a fixed number of layers. In this case,
there is a strong temporal trend for the different nodule shapes.
Narrow nodules tend to drain more laser energy through the bottom of
the nodule into the substrate while wide nodules tend to drain more
laser energy through the top of the nodule when irradiated at normal
incidence. At a 45° incidence angle, waveguiding is an additional
method to drain laser energy from the nodular defect. Finally, laser
light resonates within nodular defects longer than within the adjacent
nondefective multilayer structure.
Funder
U.S. Department of Energy
Subject
Atomic and Molecular Physics, and Optics,Engineering (miscellaneous),Electrical and Electronic Engineering
Cited by
1 articles.
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