NEW APPLICATION NOTE
Laser Microprocessing of Transparent Materials with a Visible
or IR Picosecond Fiber Laser
Processing transparent materials often requires
undesirable UV illumination, but the ultra-high peak
power of Fianium’s ultrafast fiber lasers provide a
capability of enhanced visible and IR energy absorption
through nonlinear effects. This capability provides an
avenue to marking and scribing transparent materials
such as glass, polymers and plastics, sapphire and
other crystals, and transparent conducting oxides
(TCOs). Fiber lasers are of course the preferred
embodiment over conventional free-space lasers due
to their low operating and start-up costs and extremely
low maintenance requirements.
Fianium’s high energy picosecond laser produces picosecond pulses with energies up to 125 µJ and ultra-high peak power along with
tunable repetition rates from single shot on demand and up to 40MHz, which makes it a versatile tool for high-throughput laser processing.
Fianium’s high energy picosecond lasers provide the capability of inexpensive, maintenance-free, virtually defect-free scribing, patterning
and marking of transparent materials and films for flat panel displays, back-contact layers in thin-film photovoltaics, marking and security
watermarking, as well as other applications at very high process rates.
• Up to 125 μJ pulse energy and 25W average power
• Picosecond and femtosecond pulse widths
• Single-shot to 40MHz variable repetition rate
• 1064 nm or 532 nm wavelength
• Designed for 24/7 operation and OEM integration
• Maintenance-free
Applications Lab
Fianium’s application lab in Portland, Oregon is available for clients to
evaluate the effectiveness of Fianium lasers for their custom application.
We offer a host of micromachining application capabilities including but
not limited to microprocessing of transparent materials.
End-on 3D view of a surface scribe and break of 330μm thick Sapphire made
with a high energy picosecond fiber laser from Fianium.
Picosecond laser processing of transparent
materials
Processing transparent materials has conventionally required UV
illumination that severely limits processing tool lifetimes. Not only
does UV illumination limit tool lifetimes, but it also limits material
modification to be near or on the surface of the work piece since it
cannot efficiently propagate into the material. The ultra-high peak
power of visible and IR ultrafast lasers, however, provides the capability
of nonlinear effects of enhanced absorption of energy and thus
material modification that normally would not be possible. Two photon
and multiphoton absorption can be readily achieved when focusing
picosecond pulses in the micro-Joule energy range into transparent
materials. The ultrafast pulses can be focused onto the surface of
transparent materials to etch patterns for applications like marking (see
Single-pulse removal of transparent conducting oxide thin film including
selectively removing (bottom) or leaving behind (top) an underlying
buffer layer.
NEW APPLICATION NOTE
image below), microoptics, or microfluidic devices, or to create
surface scribes for wafer dicing. The short pulsewidths not only
enable nonlinear absorption, but also result in athermal ablation
and cause no heating affects like microcracking, melting, or
recast material.
results. Since the IR or green illumination wavelengths are
transparent to the glass substrate on which the TCOs are typically
deposited, a backside (superstrate) geometry is possible. This
processing mode is utilized to remove thin films with a lift-off
mechanism that is generally cleaner than bulk removal of thin
films, requires less pulse energy, is extremely fast, and leaves
behind less debris and virtually no recast or melted material.
Microscope image of a
patterned area of TCO. The
image demonstrates the
capability
to
selectively
remove and pattern the TCO
layer in arbitrary and complex
patterns. Ultrafast processing
cleanly removes thin TCO
films, requires less pulse
energy, and leaves behind
less debris and virtually no
recast or melted material.
Micro and macroscopic patterns can be written directly on the surface .
More unique, however, is the ability of visible and IR ultrafast
pulses to both efficiently penetrate into transparent materials
and to ablate or selectively modify the bulk material. This
capability for bulk material modification, which is not possible
with UV lasers, is instrumental for a number of applications
such as waveguide writing, 3D machining, ophthalmic surgery,
fabricating security watermarks that are only visible under certain
lighting conditions, and internal scribing. An example of one of
these applications, security watermarking, is demonstrated in
the figure below where the Fianium logo written inside a glass
substrate is only visible under a certain lighting condition. The
lower two images in the figure demonstrate single pulse internal
marking of polycarbonate and borosilicate glass.
Photograph of a security watermark
written inside a glass slide.
A
rectangle was marked on the glass
surface to locate a Fianium logo
watermark, which is only visible under
particular illumination conditions
(center left). Internal marking in
polycarbonate (bottom left) and
borosilicate glass (bottom right) are
possible with ultrafast pulses in the
visible spectrum.
Another transparent material commonly associated with laser
microprocessing is a transparent conducting oxide (TCO). TCOs
are widely used in the PV, display, and consumer electronics
markets, and in some instances require laser microprocessing
to pattern thin TCO films. Conventionally this process has been
conducted with UV lasers, but utilizing the high peak power of
visible and IR ultrafast lasers can lead to significantly improved
The removal of the TCO with a picosecond fiber laser results in
extremely clean scribe channels that create excellent electrical
isolation (>20MΩ) even with scribe channels as narrow as 10 μm.
In addition to scribing the TCOs, 2D patterns can also be created
as shown in the figure above. The achievable removal rate is in
excess of 2000 mm/s and large areas can be removed at rates on
order of 100 mm2/s. The removal quality is so impeccable that
by appropriately setting the applied fluence, the buffer layer that
often separates the TCO from the glass substrate can also be
selectively removed or left behind as desired for the application.
Summary
Fianium’s IR and green picosecond fiber lasers can be used
for a variety of laser microprocessing applications involving
transparent materials such as glass, crystals, polymers, and
TCOs. The ultra-high peak power of picosecond lasers allows
for visible and IR lasers to function in a space conventionally
prescribed to UV lasers. Avoiding UV wavelengths not only extends
tool lifetimes, but also opens up applications involving bulk and
3D material modification that aren’t possible when working with
sources in the UV regime. Fianium’s picosecond fiber lasers are
capable of marking arbitrary patterns, scribing, cutting, and
etching virtually any transparent materials, in addition to being
able to create modification in the bulk for applications such as
waveguide writing, security watermarking, and internal scribing
among others. These all-fiber based lasers are the ideal reliable
and versatile tools for a vast array of industrial applications
involving transparent materials.
This note generally discusses possible uses for Fianium products. Your use could require
licensing of intellectual property, depending on the details of the system you assemble
or particular method you practice. You are solely responsible for obtaining any such
licenses and for any infringement should you fail to do so.