2 Ultrafast Laser Enabling Versatile Fabrication of Surface …
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Attributing to that, no degradation on the antireflection properties has occurred,
confirming the stability of the ultrafast fabricated SMNS. Therefore, it is demonstrated that the ultrafast laser fabricated antireflection SMNS is advantageous for both
its wavelength-independent antireflection performance and its structural robustness,
which has essential importance for practical applications.
2.5.3 General Broadband Antireflection of Metal Surfaces
via Micro-nano Dual-scale Structures
In addition to Cu, the micro-nano antireflection structures can be conveniently made
on other kinds of metal substrates by the high repetition rate high power ultrafast
laser in high efficiencies. As shown in Fig. 2.26, we have successfully produced black
Al SMNS, black Ti SMNS, and black steel SMNS, whose total reflectance in the
UV–VIS-NIR spectrum regions significantly decreases down to around 10%, 5%,
and 5%, respectively. Thus, the high repetition rate high power ultrafast laser micronano structuring approach is proved to be generally applicable in forming desired
SMNS on metal surfaces to realize highly effective optical functions.
2.6 Antireflection of Metal Surface
Macro-micronano-nanowire Multiscale Structures
2.6.1 Enhanced IR Antireflection of Metal Surfaces
via Multiscale Structures
Here, the 2D periodic surface structural architectures are taken as an example
for demonstrating the antireflection properties of the produced macro-micronanonanowire multiscale structures. When a scanning interval of 40 µm was used with
other optimized ultrafast laser conditions, micro cone arrays uniformly distributing on
the Cu surface in a periodicity of 40 µm were fabricated, among which were regular
micro holes (Fig. 2.27a). These micro cones are covered by plenty of nanoscale
features, e.g., nano particles and nano corrugations. After thermal oxidation, oxide
nanowires with a dense and uniform distribution radially grow out from the outer
surface of the micro cones, turning the micro cones to be fluffy and the micro holes
to be blurry, as shown in Fig. 2.27c.
The antireflection properties of the 2D periodic Cu multiscale structures in the
MIR region (2.5–25 µm) were measured by a mid-infrared spectroscope equipped
with an integrating sphere. As presented in Fig. 2.28, the polished Cu surface without
any SMNS has high reflectance throughout the MIR spectrum. With the micro cone
arrays fabricated above, the hemispherical reflectance of Cu surface shows a 20–
30 percentage-point decrease in comparison with the polished one. However, the
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Attributing to that, no degradation on the antireflection properties has occurred,
confirming the stability of the ultrafast fabricated SMNS. Therefore, it is demonstrated that the ultrafast laser fabricated antireflection SMNS is advantageous for both
its wavelength-independent antireflection performance and its structural robustness,
which has essential importance for practical applications.
2.5.3 General Broadband Antireflection of Metal Surfaces
via Micro-nano Dual-scale Structures
In addition to Cu, the micro-nano antireflection structures can be conveniently made
on other kinds of metal substrates by the high repetition rate high power ultrafast
laser in high efficiencies. As shown in Fig. 2.26, we have successfully produced black
Al SMNS, black Ti SMNS, and black steel SMNS, whose total reflectance in the
UV–VIS-NIR spectrum regions significantly decreases down to around 10%, 5%,
and 5%, respectively. Thus, the high repetition rate high power ultrafast laser micronano structuring approach is proved to be generally applicable in forming desired
SMNS on metal surfaces to realize highly effective optical functions.
2.6 Antireflection of Metal Surface
Macro-micronano-nanowire Multiscale Structures
2.6.1 Enhanced IR Antireflection of Metal Surfaces
via Multiscale Structures
Here, the 2D periodic surface structural architectures are taken as an example
for demonstrating the antireflection properties of the produced macro-micronanonanowire multiscale structures. When a scanning interval of 40 µm was used with
other optimized ultrafast laser conditions, micro cone arrays uniformly distributing on
the Cu surface in a periodicity of 40 µm were fabricated, among which were regular
micro holes (Fig. 2.27a). These micro cones are covered by plenty of nanoscale
features, e.g., nano particles and nano corrugations. After thermal oxidation, oxide
nanowires with a dense and uniform distribution radially grow out from the outer
surface of the micro cones, turning the micro cones to be fluffy and the micro holes
to be blurry, as shown in Fig. 2.27c.
The antireflection properties of the 2D periodic Cu multiscale structures in the
MIR region (2.5–25 µm) were measured by a mid-infrared spectroscope equipped
with an integrating sphere. As presented in Fig. 2.28, the polished Cu surface without
any SMNS has high reflectance throughout the MIR spectrum. With the micro cone
arrays fabricated above, the hemispherical reflectance of Cu surface shows a 20–
30 percentage-point decrease in comparison with the polished one. However, the