scholarly journals Characterization of Absorption Losses and Transient Thermo-Optic Effects in a High-Power Laser System

Photonics ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 94
Author(s):  
Lukasz Gorajek ◽  
Przemyslaw Gontar ◽  
Jan Jabczynski ◽  
Jozef Firak ◽  
Marek Stefaniak ◽  
...  
Keyword(s):  
High Power ◽  
Continuous Wave ◽  
Beam Quality ◽  
Laser System ◽  
Infrared Camera ◽  
High Energy ◽  
Laser Source ◽  
Transient Temperature ◽  
Temperature Profiles ◽  
Beam Diameter

(1) Background: The modeling, characterization, and mitigation of transient lasers, thermal stress, and thermo-optic effects (TOEs) occurring inside high energy lasers have become hot research topics in laser physics over the past few decades. The physical sources of TOEs are the un-avoidable residual absorption and scattering in the volume and on the surface of passive and active laser elements. Therefore, it is necessary to characterize and mitigate these effects in real laser systems under high-power operations. (2) Methods: The laboratory setup comprised a 10-kW continuous wave laser source with a changeable beam diameter, and dynamic registration of the transient temperature profiles was applied using an infrared camera. Modeling using COMSOL Multiphysics enabled matching of the surface and volume absorption coefficients to the experimental data of the temperature profiles. The beam quality was estimated from the known optical path differences (OPDs) occurring within the examined sample. (3) Results: The absorption loss coefficients of dielectric coatings were determined for the evaluation of several coating technologies. Additionally, OPDs for typical transmissive and reflective elements were determined. (4) Conclusions: The idea of dynamic self-compensation of transient TOEs using a tailored design of the considered transmissive and reflecting elements is proposed.

scholarly journals Towards Ultimate High-power Scaling: Coherent Beam Combing of Fiber Lasers

2021 ◽  
Author(s):  
Hossein Fathi ◽  
Mikko Närhi ◽  
Regina Gumenyuk
Keyword(s):  
Fiber Laser ◽  
High Power ◽  
Fiber Lasers ◽  
Continuous Wave ◽  
Beam Quality ◽  
Coherent Beam ◽  
Laser Source ◽  
Coherent Beam Combining ◽  
Beam Combining ◽  
Wide Range

Fiber laser technology has been demonstrated as a versatile and reliable approach for laser source manufacturing with a wide range of applicability in various fields ranging from science to industry. The power/energy scaling of single fiber laser systems has faced several fundamental limitations. To overcome them and to boost the power/energy level even further, combining the output powers of multiple lasers has become the primary approach. Among various combining techniques, the coherent beam combining of fiber amplification channels is the most promising approach, instrumenting ultra-high power/energy lasers with near-diffraction-limited beam quality. This paper provides a comprehensive review of the progress of coherent beam combining for both continuous-wave and ultrafast fiber lasers. The concept of coherent beam combining from basic notions to specific details of methods, requirements, and challenges are discussed, along with reporting some practical architectures for both continuous and ultrafast fiber lasers.

scholarly journals Towards Ultimate High-Power Scaling: Coherent Beam Combining of Fiber Lasers

Photonics ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 566
Author(s):  
Hossein Fathi ◽  
Mikko Närhi ◽  
Regina Gumenyuk
Keyword(s):  
Fiber Laser ◽  
High Power ◽  
Fiber Lasers ◽  
Continuous Wave ◽  
Beam Quality ◽  
Coherent Beam ◽  
Laser Source ◽  
Coherent Beam Combining ◽  
Beam Combining ◽  
Wide Range

Fiber laser technology has been demonstrated as a versatile and reliable approach to laser source manufacturing with a wide range of applicability in various fields ranging from science to industry. The power/energy scaling of single-fiber laser systems has faced several fundamental limitations. To overcome them and to boost the power/energy level even further, combining the output powers of multiple lasers has become the primary approach. Among various combining techniques, the coherent beam combining of fiber amplification channels is the most promising approach, instrumenting ultra-high-power/energy lasers with near-diffraction-limited beam quality. This paper provides a comprehensive review of the progress of coherent beam combining for both continuous-wave and ultrafast fiber lasers. The concept of coherent beam combining from basic notions to specific details of methods, requirements, and challenges is discussed, along with reporting some practical architectures for both continuous and ultrafast fiber lasers.

scholarly journals Optimized Growth and Laser Application of Yb:LuAG Single-Crystal Fibers by Micro-Pulling-Down Technique

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 78
Author(s):  
Anye Wang ◽  
Jian Zhang ◽  
Shuai Ye ◽  
Xiaofei Ma ◽  
Baiyi Wu ◽  
...  
Keyword(s):  
Single Crystal ◽  
High Power ◽  
Slope Efficiency ◽  
Continuous Wave ◽  
Beam Quality ◽  
Axial Direction ◽  
Optical Quality ◽  
Central Wavelength ◽  
High Power Lasers ◽  
Crystal Fibers

Single-crystal fibers (SCFs) have a great application potential in high-power lasers due to their excellent performance. In this work, high-quality and crack-free Yb3+:Lu3Al5O12 (Yb:LuAG) SCFs were successfully fabricated by the micro-pulling-down (μ-PD) technology. Based on the laser micrometer and the X-ray Laue diffraction results, these Yb:LuAG SCFs have a less than 5% diameter fluctuation and good crystallinity along the axial direction. More importantly, the distribution of Yb ions is proved to be uniform by electron probe microanalysis (EPMA) and the scanning electron microscope (SEM). In the laser experiment, the continuous-wave (CW) output power using a 1 mm diameter Yb:LuAG single-crystal fiber is determined to be 1.96 W, at the central wavelength of 1047 nm, corresponding to a slope efficiency of 13.55%. Meanwhile, by applying a 3 mm diameter Yb:LuAG SCF, we obtain a 4.7 W CW laser output at 1049 nm with the slope efficiency of 22.17%. The beam quality factor M2 is less than 1.1 in both conditions, indicating a good optical quality of the grown fiber. Our results show that the Yb:LuAG SCF is a potential solid-state laser gain medium for 1 μm high-power lasers.

Four-wave mixing effect on high-power continuous-wave all-fiber lasers

2018 ◽  
Vol 32 (23) ◽  
pp. 1850275
Author(s):  
Jinkun Zheng ◽  
Wei Zhao ◽  
Baoyin Zhao ◽  
Zhe Li ◽  
Gang Li ◽  
...  
Keyword(s):  
High Power ◽  
Fiber Lasers ◽  
Continuous Wave ◽  
Beam Quality ◽  
Matching Condition ◽  
Four Wave Mixing ◽  
Theoretical Description ◽  
Phase Matching ◽  
Wave Mixing ◽  
Mixing Effect

A four-wave mixing effect on high-power continuous-wave fiber lasers has been demonstrated theoretically and experimentally. Detailed theoretical description of phase matching is presented and we found that the phase matching condition is satisfied at the frequency shift of 5.16 THz. While the intensity in fiber core region is more than about 394 MW/cm2, the four-wave mixing products of 1100 nm and 1060 nm were also observed in high-power all-fiber laser. The comparison shows that the experiment result is in good agreement with the simulation result. In addition, the beam quality deterioration for the laser is caused by the four-wave mixing effect and the mode instability. The [Formula: see text] factor measured at maximal intensity of 478 MW/cm2 is 2.80.

Research on Nonlinear Degeneration and Compensation of Beam Quality in High Power Laser System

2014 ◽  
Vol 34 (2) ◽  
pp. 0214005
Author(s):  
张鲁薇 Zhang Luwei ◽  
李晓彤 Li Xiaotong ◽  
岑兆丰 Cen Zhaofeng ◽  
阮望超 Ruan Wangchao ◽  
罗红妹 Luo Hongmei
Keyword(s):  
High Power ◽  
Beam Quality ◽  
Laser System ◽  
High Power Laser ◽  
Power Laser ◽  
High Power Laser System

High power high beam quality in-band pumping picosecond amplification laser system

2015 ◽  
Vol 27 (6) ◽  
pp. 61001
Author(s):  
毛小洁 Mao Xiaojie ◽  
秘国江 Bi Guojiang ◽  
庞庆生 Pang Qingsheng ◽  
邹跃 Zou Yue ◽  
吕华昌 Lü Huachang
Keyword(s):  
High Power ◽  
Beam Quality ◽  
Laser System ◽  
High Beam ◽  
High Beam Quality

High power and beam quality continuous-wave Nd:GdVO_4 laser in-band diode-pumped at 912  nm

2017 ◽  
Vol 5 (4) ◽  
pp. 346 ◽  
Author(s):  
Mohammad Nadimi ◽  
Tanant Waritanant ◽  
Arkady Major
Keyword(s):  
High Power ◽  
Continuous Wave ◽  
Beam Quality ◽  
Diode Pumped

scholarly journals Micromachining of Invar with 784 Beams Using 1.3 ps Laser Source at 515 nm

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2962 ◽  
Author(s):  
Petr Hauschwitz ◽  
Bohumil Stoklasa ◽  
Jiří Kuchařík ◽  
Hana Turčičová ◽  
Michael Písařík ◽  
...  
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Light Emitting Diode ◽  
Laser System ◽  
Ultrashort Pulses ◽  
High Energy ◽  
Laser Source ◽  
Organic Light Emitting Diode ◽  
Energy Pulse ◽  
Cost Efficient ◽  
Monitoring Module

To fulfil the requirements for high-resolution organic light-emitting diode (OLED) displays, precise and high-quality micrometer-scale patterns have to be fabricated inside metal shadow masks. Invar has been selected for this application due to its unique properties, especially a low coefficient of thermal expansion. In this study, a novel cost-efficient method of multi-beam micromachining of invar will be introduced. The combination of a Meopta beam splitting, focusing and monitoring module with a galvanometer scanner and HiLASE high-energy pulse laser system emitting ultrashort pulses at 515 nm allows drilling and cutting of invar foil with 784 beams at once with high precision and almost no thermal effects and heat-affected zone, thus significantly improving the throughput and efficiency.

Numerical Investigation on Transient Conjugate Optical-Thermal Fields in Thin Films Irradiated by Moving Sources for Front Treatments

2010 ◽  
Vol 297-301 ◽  
pp. 1439-1444
Author(s):  
Nicola Bianco ◽  
Oronzio Manca ◽  
Daniele Ricci
Keyword(s):  
Thin Film ◽  
Maxwell Equations ◽  
Film Structure ◽  
Laser Source ◽  
Transient Temperature ◽  
Temperature Profiles ◽  
Temperature Dependent ◽  
Motion Direction ◽  
One Dimensional ◽  
Thermal Fields

In this paper a numerical analysis on two-dimensional transient of the combined optical-thermal fields caused by a moving Gaussian laser source in a multilayer thin film structure on a glass substrate is carried out. The workpiece is considered semi-infinite along the motion direction and its optical and thermophysical properties are assumed temperature dependent. The COMSOL Multiphysics 3.4 code has been used to solve the combined thermal and electromagnetic problem. In this way, the optical field is considered locally one-dimensional and Maxwell equations are solved in order to evaluate the absorption in thin film. Results, in terms of transient temperature profiles and fields, are presented for different Peclet numbers and thin film thicknesses.

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