scholarly journals Cryogenic nanosecond and picosecond high average and peak power (HAPP) pump lasers for ultrafast applications

2016 ◽  
Vol 4 ◽  
Author(s):  
David C. Brown ◽  
Sten Tornegård ◽  
Joseph Kolis
Keyword(s):  
Thermal Effects ◽  
Peak Power ◽  
Beam Quality ◽  
Damage Threshold ◽  
Nonlinear Effects ◽  
Computer Code ◽  
Laser Systems ◽  
Laser Induced Damage ◽  
Pump Lasers ◽  
Important Design

Using cryogenic laser technology, it is now possible to design and demonstrate lasers that have concomitant high average and peak powers, with near-diffraction-limited beam quality. We refer to these new laser systems as HAPP lasers. In this paper, we review important laser crystal materials properties at cryogenic temperature, with an emphasis on Yb lasers, and discuss the important design considerations, including the laser-induced damage threshold, nonlinear effects and thermal effects. A comprehensive model is presented to describe diode pulsed pumping with arbitrary duration and repetition rate, and is used with the Frantz–Nodvik equation to describe, to first order, the performance of HAPP laser systems. A computer code with representative results is also described.

scholarly journals Hexagonal boron nitride nanosheets incorporated antireflective silica coating with enhanced laser-induced damage threshold

2018 ◽  
Vol 6 ◽  
Author(s):  
Jing Wang ◽  
Chunhong Li ◽  
Wenjie Hu ◽  
Wei Han ◽  
Qihua Zhu ◽  
...  
Keyword(s):  
Boron Nitride ◽  
High Power ◽  
Damage Threshold ◽  
Fused Silica ◽  
High Power Laser ◽  
Power Laser ◽  
Silica Substrate ◽  
Laser Systems ◽  
Laser Induced Damage ◽  
Ar Coating

Boron nitride (BN) nanosheets incorporated silica antireflective (AR) coating was successfully prepared on fused silica substrate to improve the antilaser-damage ability of transmissive optics used in high-power laser systems. The BN nanosheets were obtained by urea assisted solid exfoliation, and then incorporated into basic-catalyzed silica sols without any further treatment. The transmission electron microscope (TEM) images indicated that the BN nanosheets generally consisted of 2–10 layers. The antireflective BN/$\text{SiO}_{2}$ coating exhibited excellent transmittance as high as 99.89% at 351 nm wavelength on fused silica substrate. The thermal conductivity $0.135~\text{W}\cdot \text{m}^{-1}\cdot \text{K}^{-1}$ of the BN/$\text{SiO}_{2}$ coating with 10% BN addition was about 23% higher than $0.11~\text{W}\cdot \text{m}^{-1}\cdot \text{K}^{-1}$ of the pure $\text{SiO}_{2}$ AR coating. The laser-induced damage threshold (LIDT) of that BN/$\text{SiO}_{2}$ coating is also 23.1% higher than that of pure $\text{SiO}_{2}$ AR coating. This research provides a potential application of BN/$\text{SiO}_{2}$ coatings in high-power laser systems.

scholarly journals Laser-Induced Damage Threshold of Nonlinear GaSe and GaSe:In Crystals upon Exposure to Pulsed Radiation at a Wavelength of 2.1 μm

2021 ◽  
Vol 11 (3) ◽  
pp. 1208
Author(s):  
Chongqiang Zhu ◽  
Victor Dyomin ◽  
Nikolay Yudin ◽  
Oleg Antipov ◽  
Galina Verozubova ◽  
...  
Keyword(s):  
Repetition Rate ◽  
Pulse Repetition Rate ◽  
Peak Power ◽  
Damage Threshold ◽  
Radiation Energy ◽  
Incident Radiation ◽  
Pulse Repetition ◽  
Optical Parametric Oscillators ◽  
Parametric Oscillators ◽  
Laser Induced Damage

The paper defined the laser-induced damage threshold from the fluence and the peak power of GaSe and GaSe:In single crystals upon exposure to nanosecond radiation in the two micron range and assessed the influence of test radiation energy parameters (pulse repetition rate, pulse duration) on the damage threshold. Laser-induced damage threshold was determined with the parameters of the incident radiation close to the pump radiation parameters of promising dual-wavelength optical parametric oscillators (effective pump sources for THz difference frequency oscillators): wavelength was ≈2.1 μm; pulse repetition rates were 10, 12, 14, and 20 kHz; and pulse durations were 15, 18, 20, and 22 ns. The obtained results made it possible to conclude that the value of GaSe damage threshold at a wavelength of 2.091 μm of the incident radiation was influenced by the accumulation effects (the damage threshold decreased as the pulse repetition rate increased). The accumulation effects were more significant in the case of the In-doped sample, since a more significant decrease in the damage threshold was observed with increasing frequency in terms of the peak power and the fluence.

The Optimization of Termination in Combined Technique of Magnetorheological Finishing and HF Etching for Laser-Induced Damage Threshold High-Efficiency Improving of Fused Silica

2014 ◽  
Vol 1027 ◽  
pp. 199-202
Author(s):  
Ye Tian ◽  
Xiao Qiang Peng ◽  
Yi Fan Dai ◽  
Feng Shi ◽  
Wen Wan
Keyword(s):  
High Efficiency ◽  
Experimental Parameter ◽  
Damage Threshold ◽  
Fused Silica ◽  
Fdtd Simulation ◽  
Structural Defects ◽  
Process Time ◽  
Optical Elements ◽  
Laser Systems ◽  
Laser Induced Damage

The developing high-power laser systems are requiring higher laser-induced damage threshold (LIDT) and fabrication efficiency of fused silica optical elements. To solve these problems, MRF polishing and HF etching have been combined utilized wiping and passivating structural defects as well as removing impurities. Furthermore, the LIDT improvement is dependent greatly on the corporation of processes. But the LIDT improving mechanism is partly ambiguous yet, that may lead to random or experimental parameter choice and ultimately generate unsatisfied results. Consequently, this paper focuses on the termination mechanism of the process. Atom Force Microscope (AFM) measurement, finite difference time-domain (FDTD) simulation and LIDT test will be utilized to analysis and validate the optimization theoretically and practically. Finally, in one side, the LIDT value of optimized-terminated sample is 16.7J/cm2, which is about the same level (even 3.7% higher) as that of the over-etched one. In another side, the etching process time could be shorted by 32% using the optimized method.

scholarly journals High Repetition-Rate Laser Z-Scan Measurements: Criterion for Recognizing Adverse Thermal Effects

2019 ◽  
Vol 11 (2) ◽  
pp. 73
Author(s):  
Raymond Edziah
Keyword(s):  
Repetition Rate ◽  
Thermal Effects ◽  
Nonlinear Response ◽  
Damage Threshold ◽  
High Repetition Rate ◽  
Closed Aperture ◽  
High Repetition ◽  
Fused Quartz ◽  
Laser Induced Damage ◽  
Erroneous Interpretation

This study reports z-scan measurements in which high-repetition-rate and reduced repetition-rate (pulse-picked) laser beams were employed using a standard sample, carbon disulfide (CS2) contained in supposedly high damage-threshold spectroscopic-grade pristine fused-quartz cuvettes. The results suggest that at reduced repetition rates, the closed aperture z-scan profile for CS2 displays the expected configuration. However, at high repetition-rates the closed aperture z-scans are distinctly different resulting in unexpectedly large nonlinear refractive index of CS2 due to thermal effects that resulted in below-threshold laser-induced damage of the cuvettes. Normaski microscope images confirm the damage and open aperture z-scan study of the damaged fused-quartz cuvettes yielded about two orders of magnitude enhancement in the nonlinear absorption coefficient of silica. Based on these findings, the necessary criterion for recognizing below-threshold laser-induced damage in any high-repetition-rate laser z-scan measurement has been formulated in order to help avoid erroneous interpretation of the origin and strength of nonlinear response in such studies.

FEMTOSECOND LASER-INDUCED DAMAGE OF DIELECTRICS

1999 ◽  
Vol 13 (13) ◽  
pp. 1559-1578 ◽  
Author(s):  
M. LENZNER
Keyword(s):  
Current Knowledge ◽  
Laser System ◽  
Damage Threshold ◽  
Laser Pulses ◽  
Dielectric Materials ◽  
Optical Systems ◽  
Irreversible Damage ◽  
Optical Damage ◽  
Laser Systems ◽  
Laser Induced Damage

Optical damage in non-metals (dielectrics) may severely affect the performance of high-power laser systems as well as the efficiency of optical systems based on nonlinear processes and has therefore been subject to extensive research for some 30 years. The current knowledge of laser-induced optical damage in these materials is reviewed. Emphasis is placed on the recent extension of available experimental data into the femtosecond range. Recent results are presented achieved with a sub-10 fs laser system which explores the limits of time resolution as well as the limit of intensities that a solid can sustain without irreversible damage. It is concluded that sub-10fs laser pulses open up the way to reversible nonperturbative nonlinear optics at intensities greater than 1014 W/cm 2 (slightly below damage threshold) and to nanometer-precision laser ablation (slightly above threshold) in dielectric materials.

scholarly journals Femtosecond Laser-Induced Damage Characterization of Multilayer Dielectric Coatings

Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 603 ◽  
Author(s):  
Praveen Kumar Velpula ◽  
Daniel Kramer ◽  
Bedrich Rus
Keyword(s):  
Femtosecond Laser ◽  
High Power ◽  
Damage Threshold ◽  
Test Methods ◽  
Optical Components ◽  
Damage Mechanisms ◽  
Coating Failure ◽  
Raster Scan ◽  
Laser Systems ◽  
Laser Induced Damage

The laser-induced damage threshold (LIDT) of optical components is one of the major constraints in developing high-power ultrafast laser systems. Multi-layer dielectric (MLD) coatings-based optical components are key parts of high-power laser systems because of their high damage resistance. Therefore, understanding and characterizing the laser-induced damage of MLD coatings are of paramount importance for developing ultrahigh-intensity laser systems. In this article, we overview the possible femtosecond laser damage mechanisms through damage morphologies in various MLD optical coatings tested in our facility. To evaluate the major contributions to the coating failure, different LIDT test methods (R-on-1, ISO S-on-1 and Raster Scan) were carried out for a high reflective hybrid Ta2O5/HfO2/SiO2 MLD mirror coating at a pulse duration of 37 fs. Different LIDT test methods were compared due to the fact that each test method exposes the different underlying damage mechanisms. For instance, the ISO S-on-1 test at a higher number of laser pulses can bring out the fatigue effects, whereas the Raster Scan method can reveal the non-uniform defect clusters in the optical coating. The measured LIDT values on the sample surface for the tested coating in three test methods are 1.1 J/cm2 (R-on-1), 0.9 J/cm2 (100k-on-1) and 0.6 J/cm2 (Raster Scan) at an angle of incidence of 45 deg. The presented results reveal that the performance of the tested sample is limited by coating defects rather than fatigue effects. Hence, the Raster Scan method is found to be most accurate for the tested coating in evaluating the damage threshold for practical applications. Importantly, this study demonstrates that the testing of different LIDT test protocols is necessary in femtosecond regime to assess the key mechanisms to the coating failure.

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