TY - CONF A1 - Mann, Guido A1 - Krüger, Jörg ED - Jitsuno, T. ED - Shao, J. ED - Rudolph, W. T1 - Nanosecond laser damage of optical multimode fibers N2 - For pulse laser materials processing often optical step index and gradient index multimode fibers with core diameters ranging from 100 to 600 μm are used. The design of a high power fiber transmission system must take into account limitations resulting from both surface and volume damage effects. Especially, breakdown at the fiber end faces and self-focusing in the fiber volume critically influence the fiber performance. At least operation charts are desirable to select the appropriate fiber type for given laser parameters. In industry-relevant studies the influence of fiber core diameter and end face preparation on laser-induced (surface) damage thresholds (LIDT) was investigated for frequently used all-silica fiber types (manufacturer LEONI). Experiments on preform material (initial fiber material) and compact specimens (models of the cladding and coating material) accompanied the tests performed in accordance with the relevant LIDT standards ISO 21254-1 and ISO 21254 2 for 1-on-1 and S-on-1 irradiation conditions, respectively. The relation beam diameter vs. LIDT was investigated for fused silica fibers. Additionally, laser-induced (bulk) damage thresholds of fused silica preform material F300 (manufacturer Heraeus) in dependence on external mechanical stress simulating fiber bending were measured. All experiments were performed with 10-ns laser pulses at 1064 and 532 nm wavelength with a Gaussian beam profile. T2 - Pacific Rim Laser Damage 2016 CY - Yokohama, Japan DA - 18.05.2016 KW - laser damage KW - optical fiber KW - nanosecond laser KW - fused silica PY - 2016 DO - https://doi.org/10.1117/12.2238515 VL - 9983 SP - 99830T AN - OPUS4-37140 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mann, Guido A1 - Vogel, Jens A1 - Preuß, Rüdiger A1 - Vaziri, Pouya A1 - Zoheidi, M. A1 - Eberstein, Markus A1 - Krüger, Jörg T1 - Nanosecond laser-induced surface damage of optical multimode fibers and their preforms N2 - High-power optical multimode fibers are essential components for materials processing and surgery and can limit the performance of expensive systems due to breakdown at the end faces. The aim of this paper is the determination of laser-induced damage thresholds (LIDT) of fibers (FiberTech) and preforms (Heraeus Suprasil F300). Preforms served as models. They were heated up to maximum temperatures of 1100, 1300 and 1500°C and cooled down to room temperature at rates of 10 K min-1 (oven) and ~105 K min-1 (quenched in air) to freeze in various structural states simulating different conditions similar to a drawing process during the production of fibers. Single- and multi-pulse LIDT measurements were done in accordance with the relevant ISO standards. Nd:YAG laser pulses with durations of 15 ns (1064 nm wavelength) and 8.5 ns (532 nm) at a repetition rate of 10 Hz were used. For the preforms, LIDT values (1-on-1) ranged from 220 to 350 J/cm² (1064 nm) and from 80 to 110 J/cm² (532 nm), respectively. A multi-pulse impact changed the thresholds to lower values. The LIDT (1064 nm wavelength) of the preforms can be regarded as a lower limit for those of the fibers. PY - 2008 DO - https://doi.org/10.1007/s00339-008-4576-1 SN - 0947-8396 VL - 92 IS - 4 SP - 853 EP - 857 PB - Springer CY - Berlin AN - OPUS4-17779 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Eberstein, Markus A1 - Zoheidi, M. A1 - Vogel, Jens A1 - Mann, Guido A1 - Krüger, Jörg ED - Wolf, Jonas C. ED - Luka Lange, T1 - Influence of fictive temperature on laser-induced damage of silica glass KW - Silica glass KW - Fictive temperature KW - Multimode fiber KW - Nanosecond laser KW - Damage threshold PY - 2008 SN - 978-1-60456-578-2 IS - Chapter 10 SP - 275 EP - 286 PB - Nova Science Publishers, Inc. CY - New York, USA AN - OPUS4-17903 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eberstein, Markus A1 - Mann, Guido A1 - Vogel, Jens A1 - Zoheidi, M. A1 - Krüger, Jörg T1 - Influence of Technological Parameters on Nanosecond Laser-induced Surface Damage of Optical Multimode Fibers N2 - High-power optical multimode fibers are essential components for materials processing and surgery and can limit the reliability of expensive systems due to breakdown at the end faces. The breakdown threshold of fibers is determined by intrinsic materials properties and parameters of the technology applied. The aim of this paper is the identification of technological parameters that are crucial for the fiber quality. Fibers were drawn from preforms of Heraeus SWU with core material F300 and a low amount of OH-. Both, the cladding (fluorine doped SiO2) to core diameter ratio (CCDR) and the drawing speed were varied. CCDR values between 1.05 and 1.4 were used. Afterwards, the laser-induced damage thresholds (LIDT) of the fibers were determined. For comparison, also samples from preforms, which underwent different thermal treatments above the transition temperature, were tested with respect to their damage resistivity. Single and multi pulse LIDT measurements were done in accordance with the relevant ISO standards. Nd:YAG laser pulses with durations of 15 ns (1064 nm wavelength) and 8.5 ns (532 nm) at a repetition rate of 10 Hz were utilized. For the fibers, LIDT values (1-on-1, 1064 nm and 532 nm) increased with growing CCDR and with decreasing drawing velocities. KW - Silica glass KW - Multimode fiber KW - Nanosecond laser KW - Damage threshold PY - 2005 SN - 1022-6680 SN - 1662-8985 VL - 39-40 SP - 225 EP - 230 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-17339 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mann, Guido A1 - Vogel, Jens A1 - Zoheidi, M. A1 - Eberstein, Markus A1 - Krüger, Jörg T1 - Breakdown limits of optical multimode fibers for the application of nanosecond laser pulses at 532 nm and 1064 nm wavelength N2 - For many applications, optical multimode fibers are used for the transmission of powerful laser radiation. High light throughput and damage resistance are desirable. Laser-induced breakdown at the end faces of fibers can limit their performance. Therefore, the determination of laser-induced damage thresholds (LIDT) at the surface of fibers is essential. Nanosecond (1064 nm and 532 nm wavelength) single-shot LIDT were measured according to the relevant standard on SiO2 glass preforms (Suprasil F300) as basic materials of the corresponding fibers. For 10 kinds of fused silica fibers (FiberTech) with core diameters between 180 µm and 600 µm, an illumination approach utilizing a stepwise increase of the laser fluence on a single spot was used. For both wavelengths, the LIDT values (0% damage probability) obtained by means of the two methods were compared. The influence of surface preparation (polishing) on damage resistance was investigated. For equal surface finishing, a correlation between drawing speed of the fibers and their surface LIDT values was found. In addition to the surface measurements, bulk LIDT were determined for the preform material. KW - Fiber waveguides KW - Physical radiation damage KW - Laser-beam impact phenomena KW - Glasses KW - Radiation treatment PY - 2009 DO - https://doi.org/10.1016/j.apsusc.2008.07.157 SN - 0169-4332 SN - 1873-5584 VL - 255 IS - 10 SP - 5519 EP - 5522 PB - North-Holland CY - Amsterdam AN - OPUS4-19036 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mann, Guido T1 - Influence of core diameter and coating material on nanosecond laser-induced damage threshold of optical multimode fibers T2 - European Materials Research Society (EMRS) Spring Meeting 2009, Symposium Q "Laser and Plasma Processing for Advanced Materials" CY - Strasbourg, France DA - 2009-06-08 PY - 2009 AN - OPUS4-19218 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mann, Guido T1 - Influence of core diameter and coating material on nanosecond laser-induced damage threshold of optical multicode fibers T2 - 10. Konferenz der ESG und 84. Glastechnische Tagung CY - Magdeburg, Germany DA - 2010-05-30 PY - 2010 AN - OPUS4-20891 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mann, Guido A1 - Jurke, Mathias A1 - Zoheidi, M. A1 - Eberstein, Markus A1 - Krüger, Jörg T1 - Influence of core diameter and coating material on nanosecond laser-induced damage threshold of optical multimode fibers N2 - Single and multi pulse laser-induced damage thresholds (LIDT) of core, cladding, and coating materials of high-power optical multimode fibers were determined in accordance with ISO 11254 for 532 nm and 1064 nm wavelength in the 10-ns pulse duration regime with spatial Gaussian beam shape. For all-silica fibers, LIDT increases with rising core diameter in a range between 100-600 µm for a constant cladding-core ratio of 1.2. The damage resistance of the low refracting cladding (0.3 % fluorine doped fused silica) is comparable to the undoped SiO2 core. Coating materials show significantly lower LIDT than light-guiding parts of the fibers. KW - Fiber waveguides (42.81.Qb) KW - Physical radiation damage (61.80.-x) KW - Laser-beam impact phenomena (79.20.Ds) KW - Glasses (81.05.Kf) PY - 2010 SN - 1454-4164 VL - 12 IS - 3 SP - 711 EP - 714 PB - INOE & INFM CY - Bucharest AN - OPUS4-21083 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mann, Guido T1 - Bestimmung des Wärmeübergangskoeffizienten von Kieselglas in Luft unterhalb Tg mit Unterstützung von FEM T2 - 82. Glastechnische Tagung CY - Hamelin, Germany DA - 2008-05-19 PY - 2008 AN - OPUS4-17513 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mann, Guido A1 - Vogel, Jens A1 - Preuß, Rüdiger A1 - Vaziri, Pouya A1 - Zoheidi, M. A1 - Eberstein, Markus A1 - Krüger, Jörg T1 - Nanosecond laser damage resistance of differently prepared semi-finished parts of optical multimode fibers N2 - Optical multimode fibers are applied in materials processing (e.g. automotive industry), defense, aviation technology, medicine and biotechnology. One challenging task concerning the production of multimode fibers is the enhancement of laser-induced damage thresholds. A higher damage threshold enables a higher transmitted average power at a given fiber diameter or the same power inside a thinner fiber to obtain smaller focus spots. In principle, different material parameters affect the damage threshold. Besides the quality of the preform bulk material itself, the drawing process during the production of the fiber and the preparation of the fiber end surfaces influence the resistance. Therefore, the change of the laser-induced damage threshold of preform materials was investigated in dependence on a varying thermal treatment and preparation procedure. Single and multi-pulse laser-induced damage thresholds of preforms (F300, Heraeus) were measured using a Q-switched Nd:YAG laser at 1064 nm wavelength emitting pulses with a duration of 15 ns, a pulse energy of 12 mJ and a repetition rate of 10 Hz. The temporal and spatial shape of the laser pulses were controlled accurately. Laser-induced damage thresholds in a range from 150 J cm-2 to 350 J cm-2 were determined depending on the number of pulses applied to the same spot, the thermal history and the polishing quality of the samples, respectively. KW - Laser ablation KW - Optical fibers KW - Physical radiation damage KW - Radiation treatment KW - Glass transitions KW - Glasses PY - 2007 DO - https://doi.org/10.1016/j.apsusc.2007.09.032 SN - 0169-4332 SN - 1873-5584 VL - 254 IS - 4 SP - 1096 EP - 1100 PB - North-Holland CY - Amsterdam AN - OPUS4-16207 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -