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.

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.

Laser Microprocessing of Transparent Materials with a Visible or IR Picosecond Fiber Laser

• 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

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.

Applications Lab

End-on 3D view of a surface scribe and break of 330μm thick Sapphire made with a high energy picosecond fiber laser from Fianium.

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

Picosecond laser processing of transparent materials

Single-pulse removal of transparent conducting oxide thin film including selectively removing (bottom) or leaving behind (top) an underlying buffer layer.

NEW APPLICATION NOTE

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

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.

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.

Summary

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.

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.

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.

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.

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.

Micro and macroscopic patterns can be written directly on the surface .

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.

NEW APPLICATION NOTE