With numerous manufacturers providing different laser-induced damage threshold (LIDT) values in the nanosecond regime, a simple ranking based on numbers alone may not provide a clear picture of the best choice. Variations in testing procedures, albeit following the ISO 21254 standard, further complicate the selection process. By employing a comprehensive 1-on-1 test procedure, it becomes possible to observe various parameters that influence LIDT values. When sharing test results within the community, adhering to good practices and meticulous attention to the error budget and its contributors are crucial. Above all, laser optics users must comprehend the intricacies of laser-induced damage testing and seek detailed information instead of relying solely on numerical comparisons. This study explores the challenges and considerations in selecting and testing laser optics, emphasizing the importance of a comprehensive approach.
Glass sheets with ~ 0.1 mm thickness are a promising material from which interposers for high density chip packaging can be produced due to its electrical and mechanical properties. For successful application in microelectronics, it is necessary to develop a way of efficient, high-speed production of interconnecting holes through such glass substrate, socalled through glass vias (TGVs). One of the most promising technique is Laser-Induced Deep Etching (LIDE), where picosecond laser is used to modified particular areas on the glass substrate. Then, using wet etching process, the area exposed to the laser will be etched more quickly than unexposed area. However, effective and large-scale glass modification often requires use of high-energy pulsed UV laser source, which unnecessary complicates the whole application. Here we present effective preparation of treated glass substrate using Yb:YAG laser at its fundamental wavelength 1030 nm, which is capable to overcome such disadvantage. We induced 5-15 m diameter regular affected areas on ~100 m substrate at various pitch, enabling scaled-up production of precise TGVs.
Laser-induced damage threshold (LIDT) of dielectric coatings prepared on monocrystalline neodymium-doped yttrium aluminium garnet (YAG) substrates was studied. Various coating designs were prepared using either reactive or ionassisted e-beam deposition technology and tested at 1030 nm 10 ns in r-on-1 mode according to the ISO 21254 standard. Measured damage thresholds were compared and LIDT was discussed with respect to thin-film design and coating technology.
So-called hybrid mirrors consists of broadband metallic surface coated with high reflection dielectric multilayer designed for specific wavelength. Such reflectors become more important with progressing development of multiband laser sources realized using parametric down conversion system, in particular for ultrashort-pulsed sources. Multiple pulse picosecond laser induced damage on such mirrors, tested by s-on-1 ISO-compliant method, is important part in development of such components, as there is a need in feedback predicating performance of novel designs. In following paper, we examine laser damage performance of several different designs of silver protected mirrors equipped with HR coating at 1030 nm.
Laser beam distribution system is a complex system allowing safe and precise delivery of laser beams. The new generation of HiLASE high energy diode-pumped solid state laser systems with high repetition rates requires advanced approach, which makes design of the distribution system a state-of-the-art challenge. The distribution system delivers four different laser beams multiway from laboratories to several experimental stations. We report results in design and testing of a distribution system for high-power laser beam delivery developed within the HiLASE project of the IOP in the Czech Republic. We use modular framing that allows gradual modification and flexible change of the distribution according to current laboratory needs. The system is extendable and has already proven performance.
Laser Induced Damage Threshold (LIDT) is an important property of laser system components. It is obtained as a statistical value from controlled experiments and defines the maximum optical intensity, which does not cause damage to certain components. Correlation between maximum optical intensity, beam pulse length and focal spot size provides a unique characterization of a specimen. Some specimen requires conditions or environment unreachable in stationary setup, therefore a lighten, portable, version of testing setup may be used with proper source and surroundings. The advantage of the mobile LIDT station is access to different laser systems with variety of beam properties (repetition rate, pulse length, etc). In following paper were investigated accuracy of measurements done by the mobile LIDT station and copared to stationary, ISO compliant LIDT station measurements as reference.
Several sets of fused silica and BK7 windows were anti-reflection (AR) coated for 1030 nm wavelength using ion assisted e-beam deposition under various conditions (substrate temperature, ion-beam energy). Samples were tested for laser-induced damage threshold (LIDT) at 1030 nm, 10 ns with 10 Hz repetition rate in 1000-on-1 mode according to ISO 21254 standard. Measured damage thresholds at normal (0 deg) incidence were compared and discussed.
Optical glasses, in particular fused silica and BK7, are the most common and used substrates for components manufacturing in laser technology and optics in general. Dielectric coating technologies for those materials are well known and established; both high-reflective and anti-reflective coatings prepared on such substrates demonstrated laser induced damage threshold (LIDT) exceeding tens J·cm-2 in nanosecond regime. However, LIDT became a major issue in further exploitation of crystalline materials as yttrium aluminum garnet (YAG) crystals, which often serves as a host in laser media and would be used in other components as well. One of the current challenge is the ability to transfer thin film coating technology used on glass to YAG in order to reach the same performance as in the case of fused silica or BK7 counterparts. HR dielectric coatings prepared on fused silica, BK7 and YAG substrates by reactive or ion-assisted e-beam deposition technique were tested on LIDT by s-on-1 method according to the ISO standard recommendations. Results from tests are presented and discussed in following paper.
Several sets of polished substrates were manufactured from monocrystalline yttrium-aluminium-garnet (YAG) grown by the Czochralski method. Samples were coated by both narrow-band and broad-band dielectric anti-reflection (AR) thin-film system prepared using either reactive or ion-assisted e-beam deposition technology and tested for laser-induced damage threshold (LIDT) at 1030 nm 10 ns in s-on-1 mode according to the ISO 21254 standard. Measured damage thresholds at normal (0 deg) incidence were compared for different thin-film designs and coating technology.
The “Bivoj” 10 J, 10 ns, 10 Hz, Yb:YAG (1030 nm) diode-pumped solid state laser (DPSSL) at the HiLASE Centre was used to investigate the laser-induced damage of optical glasses with different refractive index (BK7, SF8, FS, LIBA2000). The samples were polished using a combination of methods and cleaned in ultrasonic bath or with ion beams. Sample surface was characterized using white-light interferometry (WLI) and laser confocal microscopy (LCM). For the laser-induced damage threshold (LIDT), an S-on-1 procedure was selected, the testing taking place in accordance with the ISO 21254 standard. Due to the high energy per pulse of the “Bivoj” system we were capable of using beams with more than 500 μm diameter (using a long focusing mirror) and thus, including different surface defect in the LIDT measurement. The damage of the glasses was usually observed on the rear side (ballistic damage) due to constructive interference, however we manage to see on few samples front damage also. Values above 50 J/cm2 were common for all tested samples.
Yttrium aluminum garnet (YAG) crystals are one of the most important materials for active media in solid-state laser technology. Reach for higher energies brings more stress into crystals thin film coatings field, where methods used in the past are not sufficient anymore. Laser induced damage threshold (LIDT) became a major issue in further exploitation of YAG crystals as required extraction fluencies exceed tens J·cm-2 in nanosecond regime. Consequently, improved coating techniques based on e-beam deposition were introduced in order to improve damage resistance of active media. Thin films prepared on YAG crystals either by reactive or ion-assisted e-beam deposition technique were tested on LIDT by son- 1 method according to the ISO standards recommendations and results are presented in following paper.
We report recent progress in design and testing of a distribution system for high-power laser beam delivery
developed within the HiLASE project of the IOP in the Czech Republic. Laser beam distribution system is a
technical system allowing safe and precise distribution of different laser beams from laboratories to several
experimental stations. The unique nature of HiLASE lasers requires new approach, which makes design of the
distribution system a state-of-the-art challenge.
So-called hybrid mirrors, consisting of broadband metallic surface coated with dielectric reflector designed for specific
wavelength, becoming more important with progressing development of broadband mid-IR sources realized using
parametric down conversion system. Multiple pulse nanosecond laser induced damage on such mirrors was tested by
method s-on-1, where s stands for various numbers of pulses. We show difference in damage threshold between common
protected silver mirrors and hybrid silver mirrors prepared by PVD technique and their variants prepared by IAD.
Keywords: LIDT,
In this paper we present details of the commissioning of DiPOLE100, a kW-class nanosecond pulsed diode pumped solid
state laser (DPSSL), at the HiLASE Centre at Dolní Břežany in the Czech Republic. The laser system, built at the
Central Laser Facility (CLF), was dismantled, packaged, shipped and reassembled at HiLASE over a 12 month period by
a collaborative team from the CLF and HiLASE. First operation of the laser at the end of 2016 demonstrated
amplification of 10 ns pulses at 10 Hz pulse repetition rate to an energy of 105 J at 1029.5 nm, representing the world’s
first kW average power, high-energy, nanosecond pulsed DPSSL. To date DiPOLE100 has been operated for over
2.5 hours at energies in excess of 100 J at 10 Hz, corresponding to nearly 105 shots, and has demonstrated long term
energy stability of less than 1% RMS for continuous operation over 1 hour. This confirms the power scalability of multislab
cryogenic gas-cooled amplifier technology and demonstrates its potential as a laser driver for next generation
scientific, industrial, and medical applications.
Fused silica based optical fibers are broadly used for beam delivery in laser technology, mostly for continuous lasers. However, powerful pulsed beams are still very challenging for optical fiber technology; in particular in the field of pulsed lasers providing ns-length pulses or shorter at high repetition rate. According to the current knowledge, laser induced damage threshold (LIDT) of optical fiber surfaces does not achieve values generally represented for properly treated fused silica. Therefore, broader testing and understanding of optical fibers surface laser induced damage threshold and influencing factors is a key in utilization of optical fibers in pulsed lasers.
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