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Effects of ion beam etching of fused silica substrates on the laser-induced damage properties of antireflection coatings at 355?nm
摘要： Antire?ection (AR) coatings are deposited on UV grade fused silica substrates, which are cleaned in the dual ion beam sputtering device. Compared to ultrasonic and acid etching cleaning progress, ion beam etching improves the laser-induced damage threshold (LIDT) of substrates and AR coatings signi?cantly at 355 nm. Ion beam etching declines the low LIDT defects drastically and removes lots of the impurity elements (Ce, Fe, K, and Na). Roughness test shows that the AR coatings and substrates with ion beam etching are very ?at and of low roughness. Ion beam etching reduces the density of deep defect from substrates greatly. Damage morphologies show double layers delamination, which is explained via calculation of layer stress. This study will be helpful for preparation of high LIDT optical coatings.
关键词： Laser damage,AR coatings,355 nm,Substrate cleaning
更新于2025-11-14 15:19:41
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Laser damage characteristics of indium-tin-oxide film and polyimide film
摘要： This report focuses on the damage characteristics of the indium-tin-oxide (ITO) layer and the polyimide (PI) layer, which are two constituent components of a LCD. This investigation is different from the previous study, in which the alignment layer was deposited directly on a glass substrate. The PI alignment layer is pinned on the ITO film to imitate the structure of the LCD as much as possible in our current study. The damage process of the ITO/Glass sample involves melting, vaporization near the laser-induced damage threshold (LIDT), and removal at a higher fluence. However, the damage process of the PI/ITO/Glass sample involves thermally induced plastic deformation, followed by cooling when the irradiation fluence is near the LIDT, and rupture when the irradiation fluence is higher. The LIDTs of the PI/ITO/Glass samples, as determined by the on-line CCD detection technique, are higher than those of the ITO/Glass samples. The favorable mechanical properties of the PI are primarily responsible for this result.
关键词： PI film,ITO film,near-infrared laser damage
更新于2025-10-22 19:40:53
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Investigation of laser damage of grating waveguide structures submitted to sub-picosecond pulses
摘要： Grating waveguide structures (GWS) are reflective diffractive optical elements that operate based on the combination of sub-wavelength gratings (periodic microstructures) integrated with planar waveguides. They can be used for high-power laser applications for pulse compression, spectral stabilization, wavelength multiplexing, as well as polarization shaping. In this work, we investigate the laser-damage resistance of GWS based on Ta2O5/SiO2 multilayers at pulse durations of 500 fs and wavelength of 1030 nm. We particularly study the influence of the material of the multilayer sequence, the designed grating structure, and the operational conditions (angle of incidence and polarization of the laser beam) on the laser-damage resistance of the GWS. Comparison of measurements to simulation of the electric-field distribution in the structure reveals a good correlation between laser-induced damage threshold (LIDT) values and electric-field enhancement in the structure. Based on this work, an optimized design has been defined to increase the LIDT of the GWS. An improvement of the LIDT of a factor 2 has been obtained.
关键词： Ta2O5/SiO2 multilayers,Grating waveguide structures,Electric-field distribution,Sub-picosecond pulses,Laser-damage resistance
更新于2025-09-23 15:21:01
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Morphology study and threshold measurement of laser induced damage of nano-porous antireflective silica thin films in nano- and femtosecond pulse regimes
摘要： Laser induced damage threshold (LIDT) of nano-porous antire?ective silica thin ?lms is measured using 10 ns laser pulses at k = 532 nm. The thin ?lms are prepared by dip-coating of BK7 substrates and then drying them by three different heating methods, to see how their LIDT and transmission are affected. Furthermore, using SEM imaging, the morphology of the laser induced damages is inspected and compared to those of similar samples, previously irradiated by femtosecond laser pulses at k = 800 nm. The images evidently show that in the regions damaged by nanosecond pulses, the silica nanoparticles are melted and fused to each other, while in the samples irradiated by femtosecond pulses, the silica nanoparticles are sputtered and dispersed around, in the damaged area. The SEM images clearly demonstrate the different damage mechanisms involved in the nanosecond and femtosecond regimes of interaction.
关键词： Optical thin ?lms,Silica thin ?lms,Nano-porous thin ?lms,Laser damage
更新于2025-09-23 15:21:01
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LiGa0.54In0.46S2: A New Infrared Nonlinear Optical Material with Large Laser Damage Threshold Designed by Gallium substitution in LiInS2
摘要： Larger second-order harmonic generation (SHG) efficiency and high laser damage threshold (LDT) are two crucial requirements for the practical applications of IR nonlinear optical (NLO) materials. Li-(Ga, In)-Q2 (Q = S, Se) is a well-known IR NLO materials system, in which In–Q bonds are more covalent than Ga–Q bonds and benefit larger SHG efficiency. However, the incompatibility between LDT and SHG leads to a smaller LDT of LiInS2 than that of LiGaS2. A new IR NLO compound LiGa0.54In0.46S2 was successfully synthesized by the introduction of gallium in LiInS2, where mixing Ga3+ in In3+ sites result in a wider band-gap of 3.86 eV and a smaller thermal expansion anisotropy value (0.26) compared with LiInS2, leading to the large LDT of 12 times that of commercial AgGaS2 under 1064 nm at room temperature. Meanwhile, the title compound had a relatively strong SHG efficiency of about 0.6 times that of AgGaS2 under a 1910 nm laser radiation. This work highlights the strategy of pursuing IR NLO materials with high LDTs by atom doping in classic material systems.
关键词： laser damage threshold,Infrared nonlinear optical,second-order harmonic generation
更新于2025-09-23 15:19:57
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Rb <sub/>10</sub> Zn <sub/>4</sub> Sn <sub/>4</sub> S <sub/>17</sub> : A Chalcogenide with Large Laser Damage Threshold Improved from the Mn-Based Analogue
摘要： In the military and civilian fields, with the development of new technologies, high-powered nonlinear optical (NLO) crystals demonstrate broad application prospects. For purposes of designing a better NLO material, a new chalcogenide Rb10Zn4Sn4S17 was successfully designed with a high temperature solid-state method on the basis of previously reported compound Sr3MnSn2S8. The experimental results indicate that Rb10Zn4Sn4S17 possesses a prominent band gap of 3.59 eV, compared with the laser damage threshold (LDT) of Sr3MnSn2S8 (3 times that of AgGaS2); Rb10Zn4Sn4S17 shows an outstanding LDT about 5 times that of AgGaS2. Meanwhile, it has an ideal second harmonic generation (SHG) response approximately 0.7 times that of AgGaS2.
关键词： second harmonic generation (SHG),laser damage threshold (LDT),chalcogenide,nonlinear optical (NLO) crystals
更新于2025-09-19 17:13:59
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LiBa <sub/>4</sub> Ga <sub/>5</sub> Q <sub/>12</sub> (Q = S, Se): Noncentrosymmetric Metal Chalcogenides with a Cesium Chloride Topological Structure Displaying a Remarkable Laser Damage Threshold
摘要： The exploration of novel infrared nonlinear optical (IR NLO) materials with large second-harmonic generation (SHG) responses and wide band gaps has become very imperative recently. Herein we reported two noncentrosymmetric compounds, LiBa4Ga5Q12 (Q = S, Se), crystallizing in space group P421c (No. 114), which feature 3D frameworks built by a basic [Ga5Q16]17? windmill cluster and LiQ4 tetrahedra in a cesium chloride topological structure. Both compounds satisfy the desired balance between good SHG responses (～1.5× that of AgGaS2) and wide band gaps (3.43 and 2.44 eV) with remarkable laser damage thresholds (21× and 6× that of AgGaS2). The theoretical calculations uncover that the [Ga5Q16]17? cluster makes major contributions to the SHG e?ect in LiBa4Ga5Q12. In addition, the structure?performance relationship among all compounds in the I?II4?III5?VI12 system has been discussed systematically, which indicates that the introduction of the alkali metal lithium in the I site is bene?cial for the production of large band gaps. This work will be helpful in exploring novel IR NLO materials with special structures and comprehensive properties in the chalcogenide system.
关键词： chalcogenides,infrared nonlinear optical materials,laser damage thresholds,cesium chloride topological structure,second-harmonic generation
更新于2025-09-19 17:13:59
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Laser-Damage Attack Against Optical Attenuators in Quantum Key Distribution
摘要： Many quantum key distribution systems employ a laser followed by an optical attenuator to prepare weak coherent states in the source. Their mean photon number must be precalibrated to guarantee the security of key distribution. Here we experimentally show that this calibration can be broken with a high-power laser attack. We test four fiber-optic attenuator types used in quantum key distribution systems, and find that two of them exhibit a permanent decrease in attenuation after laser damage. This results in higher mean photon numbers in the prepared states and may allow an eavesdropper to compromise the key.
关键词： laser damage,optical attenuator,quantum key distribution,security
更新于2025-09-19 17:13:59
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The damage mechanism and process of metal multi-layer dielectric gratings induced by ps-pulsed laser
摘要： In the present paper, we have prepared a multi-layer grating on a layer of gold ?lm. The gratings laser damage threshold and damage morphologies have been tested using an 800 nm wavelength, 450 ps laser pulse. The gratings laser damage threshold is 0.95 J/cm2. Based on the tested damage characteristics and the calculated temperature ?eld and stress ?eld in gratings, the gratings damage mechanism has been analyzed. In theoretical calculation, the ionization process of dielectric layers in gratings and the distribution as well as evolution of the dielectric absorption coe?cient have been considered. It can be concluded that the gratings damage process is thermal ablation action dominated.
关键词： ps-pulsed laser,Metal multi-layer dielectric gratings,Laser damage
更新于2025-09-16 10:30:52
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Growth, structural, Hirshfeld surface, optical, laser damage threshold, dielectric and chemical etching analysis of 4-dimethylaminopyridinium 4-nitrophenolate 4-nitrophenol (DMAPNP)?single crystal
摘要： The organic 4-dimethylaminopyridinium 4-nitrophenolate 4-nitrophenol (DMAPNP) single crystal was grown by slow evaporation solution growth technique at 35 °C. The single crystal X-ray diffraction analysis confirms that the grown crystal belongs to the orthorhombic crystal system with the space group of P212121. Different functional groups were affirmed using FT-IR and FT-Raman analysis. The intermolecular interactions of the DMAPNP molecule were executed using Hirshfeld surface study. The Mulliken atomic charge population analysis was performed using density functional theory (DFT). The bonding interactions between two orbital atoms and groups were executed by the density of state (DOS). The optical transmittance study shows that the grown crystal has 60 to 78% transmittance in the Vis–NIR region. It has an emission peak at 482 nm in the photoluminescence (PL) spectrum. The photoconductivity analysis shows that the DMAPNP has negative photoconductive behavior. The thermal stability of the DMAPNP crystal was investigated by TG–DTA analysis. The etch pit density of the title crystal was investigated using chemical etching study. The mechanical stability of the DMAPNP crystal was tested by Vickers microhardness tester. Laser damage threshold analysis reveals that the DMAPNP is stable up to 10 mJ of laser power. The dielectric properties were assessed and the electronic polarizability of the DMAPNP was evaluated by the different empirical relations. The second harmonic generation (SHG) efficiency of DMAPNP crystal was measured by Kurtz–Perry powder technique.
关键词： optical,4-dimethylaminopyridinium 4-nitrophenolate 4-nitrophenol (DMAPNP) single crystal,Growth,chemical etching analysis,dielectric,Hirshfeld surface,structural,laser damage threshold
更新于2025-09-16 10:30:52