Multiple pulse nanosecond laser induced damage threshold on hybrid mirrors

Vanda, Jan; Muresan, Mihai-George; Bilek, Vojtech; Sebek, Matej; Hanuš, Martin; Lucianetti, Antonio; Rostohar, Danijela; Mocek, Tomáš; Škoda, Václav

doi:10.1117/12.2280561

Cited by 3 publications

(2 citation statements)

References 2 publications

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“…Hence, the most common matrix for the fabrication of such sources is silica. It is characterized by a significant damage threshold of 0.2 J/cm 2 at 1550 nm and low attenuation up to the spectral range of about 2.2 µm [16][17][18][19]. Production of silica optical fibers, due to high processing temperatures (softening point above 1700 • C), doping of silica is limited to inorganic compounds only.…”

Section: Introductionmentioning

confidence: 99%

Broadband Profiled Eye-Safe Emission of LMA Silica Fiber Doped with Tm3+/Ho3+ Ions

Miluski,

Markowski,

Kochanowicz

et al. 2023

Materials

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LMA (Large Mode Area) optical fibers are presently under active investigation to explore their potential for generating laser action or broadband emission directly within the optical fiber structure. Additionally, a wide mode profile significantly reduces the power distribution density in the fiber cross-section, minimizing the power density, photodegradation, or thermal damage. Multi-stage deposition in the MCVD-CDT system was used to obtain the structural doping profile of the LMA fiber multi-ring core doped with Tm3+ and Tm3+/Ho3+ layer profiles. The low alumina content (Al2O3: 0.03wt%) results in low refractive index modification. The maximum concentrations of the lanthanide oxides were Tm2O3: 0.18wt % and Ho2O3: 0.15wt%. The double-clad construction of optical fiber with emission spectra in the eye-safe spectral range of (1.55–2.10 µm). The calculated LP01 Mode Field Diameter (MFD) was 69.7 µm (@ 2000 nm, and 1/e of maximum intensity), which confirms LMA fundamental mode guiding conditions. The FWHM and λmax vs. fiber length are presented and analyzed as a luminescence profile modification. The proposed structured optical fiber with a ring core can be used in new broadband optical radiation source designs.

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Section: Introductionmentioning

confidence: 99%

Broadband Profiled Eye-Safe Emission of LMA Silica Fiber Doped with Tm3+/Ho3+ Ions

Miluski,

Markowski,

Kochanowicz

et al. 2023

Materials

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show abstract

“…To the best of our knowledge, this system still holds the world record of 1 kW of average output power with nanosecond pulses [11]. Many industrial applications, including laser peening and laser induced damage threshold, do not require high energy of 100 J but rather high average power and would greatly benefit from high repetition rate operation of the laser [12,13]. In order to meet these requirements, HiLASE team in cooperation with Central Laser Facility (CLF) has designed a laser amplifier with the goal to generate 10 J and 100 Hz repetition rate.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Thermal Effects in a Concept of a Cryogenically Cooled Yb: YAG Multislab 10 J/100-Hz Laser Amplifier

Sawicka-Chyla

Divoký

Slezák

et al. 2019

IEEE J. Quantum Electron.

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A thermo-optical design study of different slab geometries for a cryogenically cooled multislab amplifier operating at 10 J/ 100 Hz is presented. A finite element method (FEM) is used for 3-D analysis of heat distribution, temperature, stress and strain. From this data, birefringence, depolarization losses and wavefront distortion are calculated for a single pass through the amplifier consisting of four slabs. A comparison of different slab shapes shows that a square-shape geometry produces the smallest thermal gradients at the outer sides of the beam region, which results in smaller depolarization losses. Although the design with square-shape slabs is more sensitive to misalignment, our study shows better results compared to the case of circular-shape slabs.

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Temperature characteristics of high repetition rate water-cooled Nd:YAG active mirror amplifier

Xiao¹,

Zheng²,

Jiang³

et al. 2021

Acta Phys. Sin.

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In order to deal with the thermal management problem of high-energy high-repetition rate laser amplifiers, the efficient heat removal in water-cooled Nd:YAG active mirror amplifiers is investigated in detail through numerical modeling and experimental analysis. According to the low Reynolds number k-ε turbulence model, a full fluid-solid conjugate heat transfer model is established to give a comprehensive model of flow and thermal characteristics in three dimensions. The thermal distributions obtained from the model are then used to calculate all mechanical stresses in the laser medium and thermally-induced wavefront distortions. In comparison with the standard k-ε turbulence model, the influences of the near-wall treatments of the above model on the process of fluid flow, convection diffusion and heat conduction, and temperature distributions are analyzed. Meanwhile, the effects of coolant flow rate and pump parameter on the flow field characteristics, temperature and wavefront distributions of the YAG disk are also studied. Numerical simulation results reveal that the temperature distribution of the laser medium is closely related to the viscous effect in the solid-liquid boundary layer. Although the heat deposition distribution of the laser medium is symmetrical, the temperature profile is asymmetrical as a result of the increasing water temperature along the water flow. The maximum temperature rise of the disk is at the outlet end, and the position remains almost unchanged. The front-surface temperature distributions and wavefront profiles of Nd:YAG vary nonlinearly with the coolant flow rates, but linearly with the pump parameter. Model predictions show that when the laser amplifier operates at a repetition rate of 50 Hz, the thermal diffusion of the coolant mainly occurs in a range of 100 μm, and the maximum temperature difference of the coolant reaches up to 10.85 ℃. Correspondingly, the maximum temperature variation over the front-surface active region is less than 4 ℃, with an average temperature of 49.62 ℃, which leads to a total peak-to-valley wave front distortion of 7.27λ. The experimentally measured temperature distributions are in reasonable agreement with numerical simulations. The research results are beneficial to designing and optimizing the high-energy, high-repetition rate water-cooled Nd:YAG active mirror amplifiers.

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Multiple pulse nanosecond laser induced damage threshold on hybrid mirrors

Cited by 3 publications

References 2 publications

Broadband Profiled Eye-Safe Emission of LMA Silica Fiber Doped with Tm3+/Ho3+ Ions

Broadband Profiled Eye-Safe Emission of LMA Silica Fiber Doped with Tm3+/Ho3+ Ions

Numerical Analysis of Thermal Effects in a Concept of a Cryogenically Cooled Yb: YAG Multislab 10 J/100-Hz Laser Amplifier

Temperature characteristics of high repetition rate water-cooled Nd:YAG active mirror amplifier

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