Download resonant material processing using (ultra-)short

RESONANT MATERIAL PROCESSING USING (ULTRA-)SHORT
LASER PULSES
Ref-No: TA-CPA-1538-LZH
MBM ScienceBridge GmbH
BACKGROUND
The invention relates to the usage of a tunable, resonant electromagnetic field
for both, the targeted fabrication of structures with dimensions smaller than the
used beam diameter and the targeted fabrication of ultra small particles.
Therefore the electromagnetic field that is created by an ultra short laser pulse
on the surface of an object is superposed with an external field to achieve a
resonance rise specific to the processed material.
PROBLEM
Alexander Brinkmann
0551-30724 159
[email protected]
www.sciencebridge.de
DEVELOPMENT STATUS
Proof of concept
PATENT SITUATION
The conventional fabrication of micro- or nano-structured surfaces is of great
interest for a huge amount of industrial or R&D branches. Using (ultra) short
lasers, so called LISOS ("laser induced self organizing structures") can be
produced quite easily. Since the process is taking place in close vicinity to the
ablation threshold, it in general takes little laser intensities to fabricate these
LISOS. But in order to machine larger areas the average laser power needs to be
increased to several kilo watts. Taking today's state of the art, this again results
in high acquisition and maintenance costs for the needed laser systems
consequently raising the inhibition threshold in industry.
DE 102012025294(A1) pending
WO 2014102008(A2) pending
CATEGORIES
//Physical sciences //Optics,
photonics and laser technology
SOLUTION
When an electromagnetic field (e.g. that of a laser) hits a surface, it propagates
within the irradiated material and, depending on the laser geometry used and
the properties of the material, modes develop. If now the material is excited
resonantly (i.e. with a frequency that is specific to said material) these modes
create standing waves leading to a local increase or decrease of the
electromagnetic field on the surface. Hills are represented by nodes, valleys by
antinodes. The emerging structures have dimensions which are in the order of
the wavelength of the laser making them considerably smaller than the actual
beam diameter. The goal is now to find these resonance conditions for a variety
of materials and to reliably adjust them. In order to achieve that goal, it has been
found especially favorable to apply an external electric or magnetic field that
superposes the electromagnetic field of the laser. That way, one can directly
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control and adjust the shape of the resonant modes and therefor structural
surface parameters like the relative pattern distance or the average height
distribution.
ADVANTAGES
Only due to the resonant material processing technique a diversity of industrial
applications become economically feasible or at least much more cost effective.
Reduction of the necessary laser power
Targeted development of nano- and micro-structures
Easy adjustment and control of the resonance conditions through
external fields
Usage of more efficient materials.
SCOPE OF APPLICATION
Some application areas of the resonant material processing technique are
mentioned below:
Lowering of the reflexion of semiconductors resulting in an increase of
the efficiency of photovoltaics
Increasing the sensitivity of photo detectors
Increasing the surface of the effective area
for catalytical applications (e.g. increasing the effectiveness of
LiCoO2-cathodes used in Lithium-Ion batteries)
for tribological applications (e.g. to increase and locally confine
friction parameters)
for medical purposes (e.g. controlling cell growth, proliferation
and adhesion)
Modification of surface properties on the micrometer scale by amplifying
chemical reactions (like oxidations) in the vicinity of nodes or antinodes
Functionalization of surfaces (e.g. for lowering the wetting)
Controlled fabrication of ultra small particles.
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