Laser Damage Research Articles

Unbiased Screening of Novel Infrared Nonlinear Optical Materials with High Thermal Conductivity: Long-neglected Nitrides and Popular Chalcogenides.

Traditional infrared (IR) nonlinear optical (NLO) materials such as AgGaS2 are crucial to key devices for solid-state lasers, however, low laser damage thresholds intrinsically hinder their practical application. Here, a robust strategy is proposed for unbiased high-throughput screening of more than 140 000 materials to explore novel IR NLO materials with high thermal conductivity and wide band gap which are crucial to intrinsic laser damage threshold. Via our strategy, 106 compounds with desired band gaps, NLO coefficients and thermal conductivity are screened out, including 8 nitrides, 68 chalcogenides, in which Sr2 SnS4 is synthesized to verify the reliability of our process. Remarkably, thermal conductivity of nitrides is much higher than that of chalcogenides, e.g., 5×AgGaS2 (5.13 W/m K) for ZrZnN2 , indicating that nitrides could be a long-neglected system for IR NLO materials. This strategy provides a powerful tool for searching NLO compounds with high thermal conductivity.

Unbiased Screening of Novel Infrared Nonlinear Optical Materials with High Thermal Conductivity: Long‐neglected Nitrides and Popular Chalcogenides

AbstractTraditional infrared (IR) nonlinear optical (NLO) materials such as AgGaS2 are crucial to key devices for solid‐state lasers, however, low laser damage thresholds intrinsically hinder their practical application. Here, a robust strategy is proposed for unbiased high‐throughput screening of more than 140 000 materials to explore novel IR NLO materials with high thermal conductivity and wide band gap which are crucial to intrinsic laser damage threshold. Via our strategy, 106 compounds with desired band gaps, NLO coefficients and thermal conductivity are screened out, including 8 nitrides, 68 chalcogenides, in which Sr2SnS4 is synthesized to verify the reliability of our process. Remarkably, thermal conductivity of nitrides is much higher than that of chalcogenides, e.g., 5×AgGaS2 (5.13 W/m K) for ZrZnN2, indicating that nitrides could be a long‐neglected system for IR NLO materials. This strategy provides a powerful tool for searching NLO compounds with high thermal conductivity.

Design and preparation of resin matrix composite coating with good ablation resistance performance under high-energy laser irradiation

High-energy lasers can cause severe damage to conventional materials in an extremely short time. Highly reflective coatings are effective against damage, but they cannot withstand high laser power densities. In this study, a composite coating with two characteristics, namely, reflection and energy consumption, was designed and prepared. TiO2 and BN powders, as light reflective media, were introduced into a boron-modified phenolic resin (BPF) to prepare an anti-laser composite coating. The results show that the initial reflectivity of the composite coating can reach 78.8% at a wavelength of 1064 nm. After damage-free protection for 0.4 s, ablation occurred in the irradiation region. Owing to the formation of residual char, which is the pyrolysis product of BPF, the coating maintained its protective performance. When the composite coating was irradiated at 1000 W/cm2 for 10 s, the back-surface temperature was 186 °C, which indicates decent anti-laser performance. We also studied the role of BN by setting a control experiment. The high conductivity and energy consumption caused by the evaporation of B2O3, which is the oxidation product of BN, helped in improving the anti-laser performance. The residual char with high porosity and degree of graphitization proved to be effective to isolate laser energy. This study provides a new design for protection of conventional materials against laser damage.

Influence of defects on the femtosecond laser damage resistance of multilayer dielectric gratings.

Multilayer dielectric (MLD) gratings with high diffraction efficiency and a high laser-induced damage (LID) threshold for pulse compressors are key to scaling the peak and average power of chirped pulse amplification lasers. However, surface defects introduced by manufacturing, storage, and handling processes can reduce the LID resistance of MLD gratings and impact the laser output. The underlying mechanisms of such defect-initiated LID remain unclear, especially in the femtosecond regime. In this Letter, we model dynamic processes in interactions of a 20-fs near-infrared (NIR) laser pulse and a MLD grating design in the presence of cylindrically symmetrical nodules and particle contaminants and cracks at the surface. Utilizing a dynamic model based on a 2D finite difference in time domain (FDTD) field solver coupled with photoionization, electron collision, and refractive index modification, we study the simulation results for the damage site distribution initiated by defects of various types and sizes and its impact on the LID threshold of the grating design.

Evolution of the point defects involved under the action of mechanical forces on mechanically machined fused silica surfaces.

Point defects with different species are concentrated on most mechanically machined fused silica optical surfaces with surface defects, which would sharply decrease the laser damage resistance under intense laser irradiation. Various point defects have distinct roles in affecting the laser damage resistance. Especially, the proportions of various point defects have not been identified, posing the challenge in relating the intrinsic quantitative relationship among various point defects. To fully reveal the comprehensive effect of various point defects, it is necessary to systematically explore the origins, evolution laws and especially the quantitative relationship among point defects. Herein, seven types of point defects are determined. The unbonded electrons in point defects are found to tend to be ionized to induce laser damage and there is a definite quantitative relationship between the proportions of oxygen-deficient point defects and that of peroxide point defects. The conclusions are further verified based on the photoluminescence (PL) emission spectra and the properties (e.g., reaction rule and structural feature) of the point defects. On basis of the fitted Gaussian components and electronic-transition theory, the quantitative relationship between PL and the proportions of various point defects is constructed for the first time. E'-Center accounts for the highest proportion among them. This work is beneficial for fully revealing the comprehensive action mechanisms of various point defects and providing new insights in elucidating the defect-induced laser damage mechanisms of optical components under intense laser irradiation from the atomic scale.

Resonant Second Harmonic Generation in Proline Hybrid Lead Halide Perovskites

AbstractChiral hybrid organic−inorganic perovskites (HOIPs) with intrinsic noncentrosymmetry have shown great potentials for chiroptoelectronic applications including second‐order nonlinear optics (NLO). Ideal NLO materials should simultaneously feature a large NLO coefficient, wide optical transparency, high laser damage threshold, and physicochemical stability. However, the development of applicable second‐order NLO materials has been largely restricted due to their strict requirement on structural noncentrosymmetry. Here, chiral amino acids abundant in nature have been adopted to synthesize hybrid lead halide perovskites (D‐/L‐Pro)PbI3·H2O (Pro = Proline) with resonance enhanced second‐harmonic generation (SHG). Their crystals feature balanced NLO performances with a large NLO coefficient, wide transparent region, high laser damage threshold, and high polarization ratio. This work demonstrates the promise of naturally abundant amino acids for the construction of hybrid chiral metal halide perovskites for next generation optoelectronic materials.

Significant intensity dependence of anisotropic two-photon absorption in ZnSe and GaP

Using polarized femtosecond laser transmission measurements toward (100), (110), (111) ZnSe, and (100) GaP, we show that in a wide laser irradiation intensity range over two orders of magnitude before the laser damage threshold, a periodic amplitude modulation always appears clearly in the angle-dependent two-photon absorption (TPA) curves for (100), (110) ZnSe, and (100) GaP. It also exhibits a close connection between the orientation-dependent TPA and the ionic bonding symmetrical characteristics of specific crystal plane, thus revealing the origin of the orientation dependence of nonlinear absorption in the strong field laser-solid interaction. Interestingly, the modulation amplitudes of orientation-dependent TPA exhibit significant intensity dependence, with the maxima occurring around 1011 W cm−2. For the orientation-dependent nonlinear absorption in solids, such a nonmonotonic relationship between the irradiation intensity and the modulation amplitude has not been revealed previously in the near-damage-threshold regime by direct transmission measurements. In particular, with the intensity approaching the laser damage threshold, the significant descending trend of modulation amplitude confirms the consistent characteristics of saturation or even attenuation for the orientation dependence of TPA in the two crystals, which might be considered as a product of absorption saturation phenomenon of TPA at high irradiation intensity and would provide new understanding about the orientation-dependent TPA in the near-damage-threshold regime.

Studying Vulnerability in Quantum-Key-Distribution Systems to Attacks with Laser Damage to Optical Components Based on a Collapsing Mirror Device

Studying Vulnerability in Quantum-Key-Distribution Systems to Attacks with Laser Damage to Optical Components Based on a Collapsing Mirror Device

Machine Learning Regression Model for Predicting the Formation Energy of Nonlinear Optical Crystals

AbstractNonlinear optical crystals have been a key material in lasers due to their excellent frequency conversion properties. The search for new nonlinear crystals has been extremely active due to the inherent drawbacks of existing nonlinear crystals, such as the low laser damage threshold of infrared nonlinear crystals and the phenomenon of two‐photon absorption. The stability of a material can be characterized by calculating the formation energy, and machine learning (ML) is currently the most mainstream tool to explore materials. In this paper, the digital features of nonlinear crystals are established by using only the component information. Based on the low‐variance and cross‐validated recursive feature elimination (RFECV), 11 features with strong correlation are obtained for model training. Among them, the two features related to electronegativity account for 71.44% of all features, and become the most critical factor for the formation energy predicted by the model. Three ML regression models have been proposed to predict the formation energy of nonlinear crystals. Among them, the gradient boosting regression model shows excellent prediction performance with R2 = 0.939, RMSE = 0.205, and MAE = 0.132 eV per atom. The model provides a useful tool for fast and low‐cost prediction of nonlinear crystal formation energy.

Full-scale optic designed for onsite study of damage growth at the Laser MegaJoule facility.

Large fusion scale laser facilities aim at delivering megajoules laser energy in the UV spectrum and nanosecond regime. Due to the extreme laser energies, the laser damage of final optics of such beamlines is an important issue that must be addressed. Once a damage site initiates, it grows at each laser shot which decreases the quality of the optical component and spoil laser performances. Operation at full energy and power of such laser facilities requires a perfect control of damage kinetics and laser parameters. Monitoring damage kinetics involves onsite observation, understanding of damage growth process and prediction of growth features. Facilities are equipped with cameras dedicated to the monitoring of damage site growth. Here we propose to design and manufacture a dedicated full size optical component to study damage growth at increased energy, on the beamline, i.e. in the real environment of the optics on a large laser facility. Used for the first time in 2021, the growth statistics acquired by this approach at the Laser MegaJoule (LMJ) facility provides a new calibration point at a fluence less than 5 J cm-2 and a flat-in-time pulse of 3 ns.

Influence of the multilayer dielectric mirror design on the laser damage growth in the sub-picosecond regime.

The peak power of high-power laser facilities is limited by the laser-induced damage to the final optical components. Also, when a damage site is generated, the damage growth phenomenon limits the lifetime of the component. Many studies have been performed to improve the laser-induced damage threshold of these components. The question now arises as to whether improvement of the initiation threshold leads to a reduction of the damage growth phenomenon. To address this question, we performed damage growth experiments on three different multilayer dielectric mirror designs exhibiting different damage thresholds. We used classical quarter-wave designs and optimized designs. The experiments were carried out with a spatial top-hat beam, spectrally centered at 1053nm with a pulse duration of 0.8ps in s- and p-polarization. The results showed the impact of design on the improvement of the damage growth thresholds and a reduction of the damage growth rates. A numerical model was used to simulate damage growth sequences. The results reveal similar trends to those observed experimentally. On the basis of these three cases, we have shown that improvement of the initiation threshold through a modification of the mirror design can lead to the reduction of the damage growth phenomenon.

Optical model-based calibration of gray levels for laser damage size assessment.

Fused silica is prone to damage under ultraviolet laser irradiation. Because they are key components to achieve fusion on high energy laser facilities, final fused silica optics are analyzed after each laser shot. The quantification of damage sites is limited by the image resolution. Measurements of scattered light by damage sites allow for sub-pixel detection and growth monitoring after a calibration step based on time-consuming measurements at laser facilities. It is proven herein that modeling laser damage size monitoring based on light scattering is efficient to link gray levels to damage diameters, thereby avoiding any experimental calibration based on reference optics at the facility.

Studies on the growth and characterization of a new organic nonlinear optical single crystal: 2-amino 5-methyl-pyridinium 4-methoxybenzoate for optoelectronic and photonic devices

Single crystals of an efficient nonlinear optical material 2-amino 5-methylp yridinium 4-methoxybenzoate (2A5MP4MB) have been grown successfully from the aqueous solution by slow evaporation technique. Single crystal XRD reveals that the crystal belongs to monoclinic system with the space group P21/c. The various functional groups present in the material were ascertained by FT-IR spectral studies. The UV–Visible NIR spectrum of 2A5MP4MB shows excellent transmittance in the entire UV visible and near IR region with a lower cut off wavelength of 269 nm. The photoluminescence spectrum confirms the photon excitation process and wide band gap of the 2A5MP4MB crystal. The dielectric study on 2A5MP4MB crystal reveals normal dielectric behavior and the optical quality of the grown crystal for device applications. The laser damage threshold value of 2A5MP4MB crystal was estimated to be 4.11 GW/cm2. The third-order nonlinear optical parameters were calculated by Z-scan technique using 532 nm diode pumped CW Nd: YAG Laser and the results of the studies are discussed detail in this paper.

Effect of subsurface impurity defects on laser damage resistance of beam splitter coatings

Abstract The laser-induced damage threshold (LIDT) of plate laser beam splitter (PLBS) coatings is closely related to the subsurface absorption defects of the substrate. Herein, a two-step deposition temperature method is proposed to understand the effect of substrate subsurface impurity defects on the LIDT of PLBS coatings. Firstly, BK7 substrates are heat-treated at three different temperatures. The surface morphology and subsurface impurity defect distribution of the substrate before and after the heat treatment are compared. Then, a PLBS coating consisting of alternating HfO2–Al2O3 mixture and SiO2 layers is designed to achieve a beam-splitting ratio (transmittance to reflectance, s-polarized light) of approximately 50:50 at 1053 nm and an angle of incidence of 45°, and it is prepared under four different deposition processes. The experimental and simulation results show that the subsurface impurity defects of the substrate migrate to the surface and accumulate on the surface during the heat treatment, and become absorption defect sources or nodule defect seeds in the coating, reducing the LIDT of the coating. The higher the heat treatment temperature, the more evident the migration and accumulation of impurity defects. A lower deposition temperature (at which the coating can be fully oxidized) helps to improve the LIDT of the PLBS coating. When the deposition temperature is 140°C, the LIDT (s-polarized light, wavelength: 1064 nm, pulse width: 9 ns, incident angle: 45°) of the PLBS coating is 26.2 J/cm2, which is approximately 6.7 times that of the PLBS coating deposited at 200°C. We believe that the investigation into the laser damage mechanism of PLBS coatings will help to improve the LIDT of coatings with partial or high transmittance at laser wavelengths.

Study of the vulnerability of device based on collapsing mirror used in quantum key distribution systems

An attack on equipment with laser damage of optical components called " laser damage attack", can allow the eavesdropper to reduce the attenuation of optical elements and compromise distributed keys. A method of protection against this attack based on a device with a collapsing mirror has been considered. The conclusion based on experimental data about the effectiveness of the proposed method of protection has been made.. Keywords: quantum key distribution, laser damage attack, eavesdropper, symmetric cryptography.

Flexible optical limiters based on Cu3VSe4 nanocrystals.

Optical limiters are greatly needed to protect eyes and sensitive optoelectronic devices such as photodetectors and sensors from laser damage, but they are currently plagued by low efficiency. In this work, we utilized Cu3VSe4 nanocrystals (NCs) to enhance laser protection performance, and they exhibit higher saturation intensity and broader nonlinear spectral response extending into the near IR region than the C60 benchmark. A flexible optical limiter goggle prototype based on the NCs significantly attenuated the incident laser beam, with Z scan and I scan measurements demonstrating a giant nonlinear absorption coefficient β value of 1.0 × 10-7 m W-1, a large optical damage threshold of 3.5 J cm-2, and a small starting threshold of 0.22 J cm-2. Transient absorption spectroscopy disclosed that the origin of the excellent nonlinearity was associated with quasi-static dielectric resonance behavior and a large TPA cross-section of 3.3 × 106 GM was measured for Cu3VSe4 NCs, suggesting the potential of intermediate bandgap (IB) semiconductors as alternatives to plasmonic noble metals for ultrafast photonics. Hence, optical limiters based on such semiconductors offer new avenues for laser protection in optoelectronic and defense fields.

Research progress of laser dazzle and damage CMOS image sensor (invited)

Research progress of laser dazzle and damage CMOS image sensor (invited)

Исследование уязвимости систем квантового распределения ключей от атак с лазерным повреждением оптических компонентов на основе устройства с разрушающимся зеркалом

An attack on equipment with laser damage of optical components called "laser damage attack", can allow the eavesdropper to reduce the attenuation of optical elements and compromise distributed keys. A method of protection against this attack based on a device with a collapsing mirror has been considered. The conclusion based on experimental data about the effectiveness of the proposed method of protection has been made.

Influence of succinic acid species on structural, spectroscopic,optical, Z-scan, frequency doubling, photoconductivity and antibacterial properties of glycine single crystals

With succinic acid as an additive, glycine single crystals were grown by conventional solvent slow evaporation route. Effect of succinic acid on the growth, optical and dielectric properties of glycine polymorphs has been investigated. The occurrence of functional groups has been identified by vibrational FTIR spectrophotometer. The low value of dielectric constant and dielectric loss at higher frequency range attested the grown crystal for frequency doubling applications. The laser damage threshold energy of the grown crystal was calculated. Third order nonlinear susceptibilityχ (3) (esu) of succinic acid added glycine crystals were evaluated from Z-scan experiment.

IrSi3As3: a first transition metal arsenide non-linear optical material

Transition metal silicon arsenide with Ir–Si and Ir–As covalent bonding exhibits remarkable non-linear optical properties: high second harmonic generation activity and a large laser damage threshold.