Thin-film layer systems coated by various techniques on the optical component surface are the most common method to finishing laser optics. Anti-reflective thin-film coatings are essential in laser optics to limit unwanted retro-reflections and decrease the reflection-induced losses occurring on boundaries of optical materials and air. Several different technologies are available to prepare laser-quality coatings, when the most common are magnetron sputtering and electron-beam ion-assisted deposition. However, coating materials and deposition parameters may significantly affect both laser resistance and optical quality of the coatings, and the influence of mentioned factors is getting stronger with shorter wavelengths. In following will be disseminated laser damage threshold of anti-reflective coatings prepared by e-beam evaporation with ion assisted deposition and plasma activated reactive magnetron sputtering at wavelength 343 nm in ultra-short pulses regime.
For most of the laser applications is optics equipped with antireflective coatings must. Therefore, laser damage resistance and stability at high energies of used components is a key performance limiting factor at the large portion of the user cases. In UV region, issue of laser damage is particularly enhanced as many optical materials tends to degrade at longer exposure and any contamination may accelerate that. In the following paper will be disseminated laser damage performance of selected commercially available optical windows equipped with AR coatings, designed for high-power lasers in UV region. Damage threshold measured with mm-size laser beam will be compared and influence of the long exposure to ultrashort pulses will be considered.
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.
This article is focused on the design of a beam delivery system based on hollow-core photonic crystal fiber. For our experiment, we chose a fiber with the Kagome structure developed by GLOphotonics. The central wavelength of the delivered beam was 1030 nm, so we chose the fiber PMC-C-Yb-7C. The first part of the article is a brief introduction to PERLA 100, the laser used for testing the efficiency of the beam delivery system developed by HiLASE Centre. The reader will be acquainted with the laser system parameters. The input beam parameters play an important role in the efficiency of focusing into the fiber. One of the key parameters is the M2 of the beam, as it has a direct effect on the size of the waist at the point of entry into the fiber. Another important parameter is the maximum energy in one pulse which can destroy the fiber structure. The size of the focusing point must match the size of the MFD of the fiber. Therefore, it is necessary to precisely define the size of the input beam into the focusing assembly with an accuracy of micrometers and to get rid of as many degrees of freedom as possible in the actual setup of the entire system. Another critical parameter is the size of the fiber input angle. The article aims to eliminate as many critical points as possible when setting up a focusing system and thus prevent damage to the fiber structure. One of the points is the simulation and calculation of the maximum possible loading of the fiber microstructure before its damage. With the help of gradual design modification, the aim is to achieve a coupling efficiency of more than 90 % by scaling the PERLA 100 output power from units of W up to 100 W.
Laser-Induced Deep Etching (LIDE) is considered as the one of the most promising techniques for production of so-called TGVs (Through Glass Vias). In the production process, thin glass sheet is treated with ultra-short lasers pulses to induce surface and volume modification, allowing efficient wet etching and formation of through hole. Precise knowledge of damage threshold of such glass is essential when optimizing the whole process and scaling up the production via laser beam parallelization. In following paper, we present recent results on LIDT measurement of D263 glass sheets at wavelengths 1030 nm and 515 nm, effective utilization of such knowledge for setting up multi-Bessel beam processing optics, and we demonstrate resulting substrates with TGVs.
The removal of multi-compound protective thin PVD films for stressed industrial tools using laser ablation could enhance or replace currently used procedures. Developing a laser removal process can shorten the processing time and costs. In the first step, the laser-induced damage threshold of the thin CrAlSiN coating and the WC-Co material was measured. Nanosecond and picosecond laser pulses were used for comparison. Furthermore, the dependence of the ablated material volume and ablation depth on the fluence and the number of pulses was measured. Finally, spectral analysis of the laser plasma generated during ablation was performed.
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.
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 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.
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.
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