scholarly journals Cumulative material damage from train of ultrafast infrared laser pulses

2019 ◽  
Vol 7 ◽  
Author(s):  
A. Hanuka ◽  
K. P. Wootton ◽  
Z. Wu ◽  
K. Soong ◽  
I. V. Makasyuk ◽  
...  
Keyword(s):  
Damage Threshold ◽  
Laser Pulses ◽  
Critical Value ◽  
Fused Silica ◽  
Material Damage ◽  
Single Shot ◽  
Threshold Fluence ◽  
Intrinsic Parameter ◽  
Asymptotic Value ◽  
Extrinsic Parameters

We developed a systematic experimental method to demonstrate that damage threshold fluence (DTF) for fused silica changes with the number of femtosecond laser (800 nm, $65\pm 5~\text{fs}$, 10 Hz and 600 Hz) pulses. Based on the experimental data, we were able to develop a model which indicates that the change in DTF varies with the number of shots logarithmically up to a critical value. Above this value, DTF approaches an asymptotic value. Both DTF for a single shot and the asymptotic value as well as the critical value where this happens, are extrinsic parameters dependent on the configuration (repetition rate, pressure and geometry near or at the surface). These measurements indicate that the power of this dependence is an intrinsic parameter independent of the configuration.

scholarly journals Laser-induced damage thresholds of ultrathin targets and their constraint on laser contrast in laser-driven ion acceleration experiments

2020 ◽  
Vol 8 ◽  
Author(s):  
Dahui Wang ◽  
Yinren Shou ◽  
Pengjie Wang ◽  
Jianbo Liu ◽  
Zhusong Mei ◽  
...  
Keyword(s):  
Damage Threshold ◽  
Wide Band ◽  
Laser Pulses ◽  
Laser Damage Threshold ◽  
Single Shot ◽  
Bulk Materials ◽  
Free Standing ◽  
Wide Band Gap ◽  
Different Types ◽  
Laser Induced Damage

Abstract Single-shot laser-induced damage threshold (LIDT) measurements of multi-type free-standing ultrathin foils were performed in a vacuum environment for 800 nm laser pulses with durations τ ranging from 50 fs to 200 ps. The results show that the laser damage threshold fluences (DTFs) of the ultrathin foils are significantly lower than those of corresponding bulk materials. Wide band gap dielectric targets such as SiN and formvar have larger DTFs than semiconductive and conductive targets by 1–3 orders of magnitude depending on the pulse duration. The damage mechanisms for different types of targets are studied. Based on the measurement, the constrain of the LIDTs on the laser contrast is discussed.

scholarly journals Laser-Induced Point Defects in Fused Silica Irradiated by UV Laser in Vacuum

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaoyan Zhou ◽  
Xinda Zhou ◽  
Jin Huang ◽  
Qiang Cheng ◽  
Fengrui Wang ◽  
...  
Keyword(s):  
Point Defects ◽  
Fluorescence Spectra ◽  
Uv Spectroscopy ◽  
Damage Threshold ◽  
Laser Pulses ◽  
Fused Silica ◽  
Third Harmonic ◽  
Structural Modifications ◽  
Laser Induced Damage ◽  
Induced Defects

High-purity fused silica irradiated by third harmonic of the Nd:YAG laser in vacuum with different laser pulse parameters was studied experimentally. Laser-induced defects are investigated by UV spectroscopy, and fluorescence spectra and correlated to the structural modifications in the glass matrix through Raman spectroscopy. Results show that, for laser fluence below laser-induced damage threshold (LIDT), the absorbance and intensity of fluorescence bands increase with laser energies and/or number of laser pulses, which indicates that laser-induced defects are enhanced by laser energies and/or number of laser pulses in vacuum. The optical properties of these point defects were discussed in detail.

scholarly journals SSD detection on LIDT tested coated Fused Silica samples

2021 ◽  
Vol 255 ◽  
pp. 03009
Author(s):  
Heidi Cattaneo ◽  
Daniel Schachtler ◽  
Roelene Botha ◽  
Oliver Fähnle
Keyword(s):  
Laser Energy ◽  
Substrate Surface ◽  
Single Layer ◽  
Damage Threshold ◽  
Surface Damage ◽  
Laser Pulses ◽  
Fused Silica ◽  
Small Surface ◽  
Additional Information ◽  
Laser Induced Damage

Material changes and Sub-Surface Damage (SSD) under Laser Induced Damage Threshold (LIDT) testing sites were investigated on 3 diverse single layer coated transparent fused silica samples to obtain additional information on damage precursors on these samples. As a detection method, photothermal deflection technique utilizing a resonant UV laser beam was used. The local variations in UV absorption and probe beam transmittance due to previous exposure to high fluence laser pulses were strongly dependent on the coating itself and on the laser energy used during the LIDT testing. Also the obtained LIDT values differ from coating to coating. Detected effects on the coatings and substrate surface beneath ranged from small surface dislocations to complete coating damage with material transformations. Additional absorbing damage precursors were found close to the damaged sites.

Fracture of fused silica with 351 nm laser-generated surface cracks

1999 ◽  
Vol 14 (2) ◽  
pp. 597-605 ◽  
Author(s):  
F. Dahmani ◽  
J. C. Lambropoulos ◽  
A. W. Schmid ◽  
S. Papernov ◽  
S. J. Burns
Keyword(s):  
Crack Depth ◽  
Damage Threshold ◽  
Surface Damage ◽  
Laser Pulses ◽  
Fused Silica ◽  
Material Strength ◽  
Failure Strength ◽  
Exit Surface ◽  
Four Point Bending ◽  
Underlying Basis

Laser-induced-surface-flaw experiments on fused silica at 351 nm and 500 ps pulse duration are reported here. Specimens with surface flaws produced at a measured exit-surface damage threshold fluence of Fexit/th = 10 J/cm2 were irradiated at a constant fluence of FL = 1.8 × Fexit/th by different numbers of laser pulses, N = 110 to 520. Micrograph observations show that (i) the produced cracks have a semielliptical shape and (ii) the material strength predictions based on the radial crack depth (normal to the surface) instead of the crack surface length (parallel to the surface) are in good agreement with measured strengths obtained using a four-point bending fixture. The underlying basis of conventional crack analysis is first examined critically and is argued to be deficient in the way the failure strength for the cracks is related to the characteristic parameters of crack geometry. In general, it is necessary to incorporate a residual term into the failure strength formulation. The crack depth and the failure strength are found to increase and decrease with the number of laser pulses, respectively.

scholarly journals High laser induced damage threshold photoresists for nano-imprint and 3D multi-photon lithography

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Elmina Kabouraki ◽  
Vasileia Melissinaki ◽  
Amit Yadav ◽  
Andrius Melninkaitis ◽  
Konstantina Tourlouki ◽  
...  
Keyword(s):  
Nanoimprint Lithography ◽  
Three Dimensional ◽  
Damage Threshold ◽  
Laser Pulses ◽  
Intense Laser ◽  
Optical Elements ◽  
Photonic Circuits ◽  
Future Production ◽  
Intense Laser Pulses ◽  
Laser Induced Damage

Abstract Optics manufacturing technology is predicted to play a major role in the future production of integrated photonic circuits. One of the major drawbacks in the realization of photonic circuits is the damage of optical materials by intense laser pulses. Here, we report on the preparation of a series of organic–inorganic hybrid photoresists that exhibit enhanced laser-induced damage threshold. These photoresists showed to be candidates for the fabrication of micro-optical elements (MOEs) using three-dimensional multiphoton lithography. Moreover, they demonstrate pattern ability by nanoimprint lithography, making them suitable for future mass production of MOEs.

scholarly journals Laser-induced thermal grating spectroscopy based on femtosecond laser multi-photon absorption

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maria Ruchkina ◽  
Dina Hot ◽  
Pengji Ding ◽  
Ali Hosseinnia ◽  
Per-Erik Bengtsson ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Laser Pulses ◽  
Photon Absorption ◽  
Gas Flows ◽  
Single Shot ◽  
Photon Excitation ◽  
Fs Laser ◽  
Thermal Grating ◽  
Grating Spectroscopy ◽  
First Time

AbstractLaser-induced grating spectroscopy (LIGS) is for the first time explored in a configuration based on the crossing of two focused femtosecond (fs) laser pulses (800-nm wavelength) and a focused continuous-wave (cw) laser beam (532-nm wavelength). A thermal grating was formed by multi-photon absorption of the fs-laser pulses by $$\hbox {N}_{{2}}$$ N 2 with a pulse energy around 700 $$\upmu $$ μ J ($$\sim $$ ∼ 45 TW/$$\hbox {cm}^{2}$$ cm 2 ). The feasibility of this LIGS configuration was investigated for thermometry in heated nitrogen gas flows. The temperature was varied from room temperature up to 750 K, producing strong single-shot LIGS signals. A model based on the solution of the linearized hydrodynamic equations was used to extract temperature information from single-shot experimental data, and the results show excellent agreement with the thermocouple measurements. Furthermore, the fluorescence produced by the fs-laser pulses was investigated. This study indicates an 8-photon absorption pathway for $$\hbox {N}_{{2}}$$ N 2 in order to reach the $$\hbox {B}^{3}\Pi _{g}$$ B 3 Π g state from the ground state, and 8 + 5 photon excitation to reach the $$\hbox {B}^{2}\Sigma _{u}^{+}$$ B 2 Σ u + state of the $$\hbox {N}_{2}^{+}$$ N 2 + ion. At pulse energies higher than 1 mJ, the LIGS signal was disturbed due to the generation of plasma. Additionally, measurements in argon gas and air were performed, where the LIGS signal for argon shows lower intensity compared to air and $$\hbox {N}_{{2}}$$ N 2 .

High power supercontinuum generation by dual-color femtosecond laser pulses in fused silica

2021 ◽  
Author(s):  
Saba Zafar ◽  
Dong-Wei Li ◽  
Acner Camino ◽  
Jun-Wei Chang ◽  
Zuo-Qiang Hao
Keyword(s):  
Femtosecond Laser ◽  
High Power ◽  
Microlens Array ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Fused Silica ◽  
Spectral Energy ◽  
Phase Matching ◽  
Fundamental Wavelength ◽  
Fundamental Laser

Abstract High power supercontinuum (SC) is generated by focusing 800 nm and 400 nm femtosecond laser pulses in fused silica with a microlens array. It is found that the spectrum of the SC is getting broader compared with the case of single laser pulse, and the spectral energy density between the two fundamental laser wavelengths is getting significantly higher by optimizing the phase matching angle of the BBO. It exceeds μJ/nm over 490 nm range which is from 380 nm to 870 nm, overcoming the disadvantage of relative lower power in the ranges far from fundamental wavelength.

Transient reflectivity and transmission changes during plasma formation and ablation in fused silica induced by femtosecond laser pulses

2008 ◽  
Vol 92 (4) ◽  
pp. 803-808 ◽  
Author(s):  
D. Puerto ◽  
W. Gawelda ◽  
J. Siegel ◽  
J. Bonse ◽  
G. Bachelier ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Fused Silica ◽  
Plasma Formation
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