Infrared Laser Beam Research Articles

Attosecond vortex pulse trains

The landscape of ultrafast structured light pulses has significantly advanced thanks to the ability of high-order harmonic generation (HHG) to translate the spatial properties of infrared laser beams to the extreme-ultraviolet (EUV) spectral range. In particular, the up-conversion of orbital angular momentum (OAM) has enabled the generation of high-order harmonics whose OAM scales linearly with the harmonic order and the topological charge of the driving field. Having a well-defined OAM, each harmonic is emitted as an EUV femtosecond vortex pulse. However, the order-dependent OAM across the harmonic comb precludes the synthesis of attosecond vortex pulses. Here we demonstrate a method for generating attosecond vortex pulse trains, i.e., a succession of attosecond pulses with a helical wavefront, resulting from the coherent superposition of a comb of EUV high-order harmonics with the same OAM. By driving HHG with a polarization tilt-angle fork grating, two spatially separated circularly polarized high-order harmonic beams with order-independent OAM are created. Our work opens the route towards attosecond-resolved light-matter interactions with two extra degrees of freedom, spin and OAM, which are particularly interesting for probing chiral systems and magnetic materials.

High-angular-momentum Rydberg states in a room-temperature vapor cell for dc electric-field sensing

We prepare and analyze Rydberg states with orbital quantum numbers ℓ≤6 using three-optical-photon electromagnetically induced transparency (EIT) and radio frequency (rf) dressing, and employ the high-ℓ states in electric-field sensing. Rubidium-85 atoms in a room-temperature vapor cell are first promoted into the 25F5/2 state via Rydberg-EIT with three infrared laser beams. Two rf dressing fields then (near-)resonantly couple the 25F, 25H(ℓ=5), and 25I(ℓ=6) Rydberg states. The dependence of the rf-dressed Rydberg-state level structure on rf powers, rf and laser frequencies is characterized using EIT. Furthermore, we discuss the principles of dc-electric-field sensing using high-ℓ Rydberg states and experimentally demonstrate the method using test electric fields of ≲50 V/m induced via photo-illumination of the vapor-cell wall. We measure the highly nonlinear dependence of the dc-electric-field strength on the power of the photo-illumination laser. Numerical calculations, which reproduce our experimental observations well, elucidate the underlying physics. Our paper is relevant to high-precision spectroscopy of high-ℓ Rydberg states, Rydberg-atom-based electric-field sensing, and plasma electric-field diagnostics. Published by the American Physical Society 2024

Microstructure, hardness, and tribological properties of CoCrFeNiX (X = Mo, Ti, W) high entropy alloy coating by red-blue composite laser cladding on copper alloy

In this study, the problem of high reflectivity of copper alloy surface to traditional infrared laser beam was overcome by red-blue composite laser cladding technology. The problem of cracks and other defects caused by the large difference in thermal expansion coefficient between copper substrate and high entropy alloy coating was overcome by electroplating Ni intermediate layer on the surface of copper alloy. A high-entropy alloy coating with tight bonding and no obvious defects was successfully prepared on the surface of copper alloy. The phase composition, microstructure evolution, hardness and tribological properties of high-entropy alloy coatings after adding different elements were studied. The experimental results show that all the CoCrFeNi coatings are FCC phase. After the addition of Mo, Ti and W elements, σ phase rich in Mo and Cr, TiCo2-type Laves phase and Fe7W6-type μ phase appeared in the high entropy alloy coating, respectively. The average microhardness of CoCrFeNiX (X = Mo, Ti, W) high entropy alloy coatings reached 730 HV0.2, 1090 HV0.2 and 378 HV0.2, respectively. The wear rates of CoCrFeNiMo, CoCrFeNiTi and CoCrFeNiW high-entropy alloy coatings were 47.17 %, 90.56 % and 22.64 % lower than those of CoCrFeNi coating, respectively. The wear scars were analyzed by SEM and EDS, and the friction and wear behavior mechanism of CoCrFeNiX (X = Mo, Ti, W) high-entropy alloy coating was investigated. It is mainly composed of abrasive wear, adhesive wear and oxidation wear. The research results provide practical guidance for the preparation of high-entropy alloy coatings on copper surface, and lay a theoretical foundation for laser cladding such high-entropy alloy materials and substrate materials.

Directed high-energy infrared laser beams for photovoltaic generation of electric power at remote locations

Transferring energy without transferring mass is a powerful paradigm to address the challenges faced when the access to, or the deployment of, the infrastructure for energy conversion is locally impossible or impractical. Laser beaming holds the promise of effectively implementing this paradigm. With this perspective, this work evaluates the optical-to-electrical power conversion that is created when a collimated laser beam illuminates a silicon photovoltaic solar cell that is located kilometers away from the laser. The laser is a CW high-energy Yb-doped fiber laser emitting at a center wavelength of 1075 nm with ∼1 m2 of effective beam area. For 20 kW illumination of a solar panel having 0.6 m2 of area, optical simulations and thermal simulations indicate an electrical output power of 3000 W at a panel temperature of 550 K. Our investigations show that thermo-radiative cells are rather inefficient. In contrast, an optimized approach to harvest laser energy is achieved by using a hybrid module consisting of a photovoltaic cell and a thermoelectric generator. Finally, practical considerations related to infrared power beaming are discussed and its potential applications are outlined.

Wavefront-enhanced laser-induced breakdown spectroscopy (WELIBS) utilizing a crystalline silicon wafer for a flat-top IR laser beam

On passing through a thin crystalline silicon wafer, the profile of an infrared laser beam is changed from a quasi-Gaussian to a flat-top one, improving the LIBS technique's analytical performance. That is the proposed (WELIBS) Wavefront-enhanced laser-induced breakdown spectroscopy approach.

Comparison of quartz and sapphire optical chambers for infrared laser sealing of vascular tissues using a reciprocating, side-firing optical fiber: Simulations and experiments.

Infrared (IR) lasers are being tested as an alternative to radiofrequency (RF) and ultrasonic (US) surgical devices for hemostatic sealing of vascular tissues. In previous studies, a side-firing optical fiber with elliptical IR beam output was reciprocated, producing a linear IR laser beam pattern for uniform sealing of blood vessels. Technical challenges include limited field-of-view of vessel position within the metallic device jaws, and matching fiber scan length to variable vessel sizes. A transparent jaw may improve visibility and enable custom treatment. Quartz and sapphire square optical chambers (2.7 × 2.7 × 25 [mm3 ] outer dimensions) were tested, capable of fitting into a 5-mm-OD laparoscopic device. A 1470 nm laser was used for optical transmission studies. Razor blade scans and an IR beam profiler acquired fiber (550-µm-core/0.22NA) output beam profiles. Thermocouples recorded peak temperatures and cooling times on internal and external chamber surfaces. Optical fibers with angle polished distal tips delivered 94% of light at a 90° angle. Porcine renal arteries with diameters of 3.4 ± 0.7 mm (n = 13) for quartz and 3.2 ± 0.7 mm (n = 14) for sapphire chambers (p > 0.05), were sealed using 30 W for 5 s. Reflection losses at material/air interfaces were 3.3% and 7.4% for quartz and sapphire. Peak temperatures on the external chamber surface averaged 74 ± 8°C and 73 ± 10°C (p > 0.05). Times to cool down to 37°C measured 13 ± 4 s and 27 ± 7 s (p < 0.05). Vessel burst pressures (BP) averaged 883 ± 393 mmHg and 412 ± 330 mmHg (p < 0.05). For quartz, 13/13 (100%) vessels were sealed (BP > 360 mmHg), versus 9/14 (64%) for sapphire. Computer simulations for the quartz chamber yielded peak temperatures (78°C) and cooling times (16 s) similar to experiments. Quartz is an inexpensive material for use in a laparoscopic device jaw, providing more consistent vessel seals and faster cooling times than sapphire and current RF and US devices.

Investigations on laser beam welding of thin aluminum foils with additional filler wire

Nowadays, battery-electric drives and energy storage are elected to be the future technologies. In the manufacturing of parts for electric applications, laser beam welding is an appropriate and favorable welding method. The characteristics of high welding speed, local heat input, and the contact-free process allow efficient and automatable processes. For electrodes, mainly copper and aluminum are used. Many foils with thicknesses of an area of 10 μm have to be connected to create battery cells. Different than expected, aluminum is a more challenging material to produce than others. Pore formation is also extended in aluminum due to the presence of air between the foils. The connecting cross section is thereby reduced. Furthermore, there is detachment in the fusion area and a high weld seam undercut. In addition to insufficient clamping, a lack of material reduces strength and, thus, usability. In the research presented here, the use of aluminum filler wire (AA 1050A) and shielding gas are investigated for the application of welding 40 aluminum foils (AA 1050A) with a thickness of 15 μm to an aluminum sheet with a thickness of 2 mm using infrared laser beam wavelength. The aims of the process development are welds with high connection widths and high quality as well as reproducibility to provide excellent mechanical properties and the highest electrical conductivity.

Combining LAESI Imaging and Tissue Spray Ionization Mass Spectrometry To Unveil Pesticides Contaminants in Fruits.

There is an increasing need for developing a strategy to analyze the penetration of pesticides in cultures during postharvest control with minimal or no sample preparation. This study explores the combined use of laser ablation electrospray ionization mass spectrometry imaging (LAESI imaging) and tissue spray ionization mass spectrometry (TSI-MS) to investigate the penetration of thiabendazole (TBZ) in fruits, simulating a postharvest procedure. Slices of guava and apple were prepared, and an infrared laser beam was used, resulting in the ablation of TBZ directly ionized by electrospray and analyzed by mass spectrometry. The experiments were conducted for 5 days of fruit storage after TBZ administration to simulate a postharvest treatment. During postharvest treatment, TBZ is applied directly to the fruit peel after harvesting. Consequently, TBZ residues may remain on the peel if the consumer does not wash the fruit properly before its consumption. To evaluate the effectiveness of household washing procedures, TSI-MS was employed as a rapid and straightforward technique to monitor the remaining amount of TBZ in guava and apple peels following fruit washing. This study highlights the advantages of LAESI imaging for evaluating TBZ penetration in fruits. Moreover, the powerful capabilities of TSI-MS are demonstrated in monitoring and estimating TBZ residues after pesticide application, enabling the comprehensive unveiling of pesticide contaminants in fruits.

Laser-induced molecular contamination de-risking activity for the Laser Interferometer Space Antenna.

The Laser Interferometer Space Antenna (LISA) will be the first space-based gravitational wave observatory. LISA uses continuous-wave, infrared laser beams propagating among three widely separated spacecrafts to measure their distances with picometer accuracy via time-delay interferometry. These measurements put very high demands on the laser wavefront and are thus very sensitive to any deposits on laser optics that could be induced by laser-induced molecular contamination (LIMC). In this work, we describe the results of an extensive experimental test campaign assessing LIMC related risks for LISA. We find that the LIMC concern for LISA, even considering the high demands on the laser wavefront, may be greatly reduced compared to that observed at shorter wavelengths or with pulsed laser radiation. This result is very promising for LISA as well as for other space missions using continuous-wave, infrared laser radiation, e.g.,in free space laser communication or quantum key distribution.

Infrared spectroscopy of cations in helium nanodroplets.

Here, we describe our pulsed helium droplet apparatus for spectroscopy of molecular ions. Our approach involves the doping of the droplets of about 10nm in diameter with precursor molecules, such as ethylene, followed by electron impact ionization. Droplets containing ions are irradiated by the pulsed infrared laser beam. Vibrational excitation of the embedded cations leads to the evaporation of the helium atoms in the droplets and the release of the free ions, which are detected by the quadrupole mass spectrometer. In this work, we upgraded the experimental setup by introducing an octupole RF collision cell downstream from the electron impact ionizer. The implementation of the RF ion guide increases the transmission efficiency of the ions. Filling the collision cell with additional He gas leads to a decrease in the droplet size, enhancing sensitivity to the laser excitation. We show that the spectroscopic signal depends linearly on the laser pulse energy, and the number of ions generated per laser pulse is about 100 times greater than in our previous experiments. These improvements facilitate faster and more reproducible measurements of the spectra, yielding a handy laboratory technique for the spectroscopic study of diverse molecular ions and ionic clusters at low temperature (0.4K) in He droplets.

Applying Optical Tweezers with TIRF Microscopy to Quantify Physical Interactions Between Organelles in the Plant Endomembrane System.

Plant organelles are associated with each other through tethering proteins at membrane contact sites (MCS). Methods such as total internal reflection fluorescence (TIRF) optical tweezers allow us to probe organelle interactions in live plant cells. Optical tweezers (focused infrared laser beams) can trap organelles that have a different refractive index to their surrounding medium (cytosol), whilst TIRF allows us to simultaneously image behaviors of organelles in the thin region of cortical cytoplasm. However, few MCS tethering proteins have so far been identified and tested in a quantitative manner. Automated routines (such as setting trapping laser power and controlling the stage speed and distance) mean we can quantify organelle interactions in a repeatable and reproducible manner. Here we outline a series of protocols which describe laser calibrations required to collect robust data sets, generation of fluorescent plant material (Nicotiana tabacum, tobacco), how to set up an automated organelle trapping routine, and how to quantify organelle interactions (particularly organelle interactions with the endoplasmic reticulum). TIRF-optical tweezers enable quantitative testing of putative tethering proteins to reveal their role in plant organelle associations at MCS. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Microscope system set-up and stability Basic Protocol 2: Generation of transiently expressed fluorescent tobacco tissue by Agrobacterium-mediated infiltration Basic Protocol 3: Setting up an automated organelle trapping routine Basic Protocol 4: Quantifying organelle interactions.

Synthesis of Antibacterial Copper Oxide Nanoparticles by Pulsed Laser Ablation in Liquids: Potential Application against Foodborne Pathogens.

Spherical copper oxide nanoparticles (CuO/Cu2O NPs) were synthesized by pulsed laser ablation in liquids (PLAL). The copper target was totally submerged in deionized (DI) water and irradiated by an infrared laser beam at 1064 nm for 30 min. The NPs were then characterized by dynamic light scattering (DLS) and atomic emission spectroscopy (AES) to determine their size distribution and concentration, respectively. The phases of copper oxide were identified by Raman spectroscopy. Then, the antibacterial activity of CuO/Cu2O NPs against foodborne pathogens, such as Salmonella enterica subsp. enterica serotype Typhimurium DT7, Escherichia coli O157:H7, Shigella sonnei ATCC 9290, Yersinia enterocolitica ATCC 27729, Vibrio parahaemolyticus ATCC 49398, Bacillus cereus ATCC 11778, and Listeria monocytogenes EGD, was tested. At a 3 ppm concentration, the CuO/Cu2O NPs exhibited an outstanding antimicrobial effect by killing most bacteria after 5 h incubation at 25 °C. Field emission scanning electron microscope (FESEM) confirmed that the CuO/Cu2O NPs destructed the bacterial cell wall.

Laser-Activated Second Harmonic Generation in Flexible Membrane with Si Nanowires.

Nonlinear silicon photonics has a high compatibility with CMOS technology and therefore is particularly attractive for various purposes and applications. Second harmonic generation (SHG) in silicon nanowires (NWs) is widely studied for its high sensitivity to structural changes, low-cost fabrication, and efficient tunability of photonic properties. In this study, we report a fabrication and SHG study of Si nanowire/siloxane flexible membranes. The proposed highly transparent flexible membranes revealed a strong nonlinear response, which was enhanced via activation by an infrared laser beam. The vertical arrays of several nanometer-thin Si NWs effectively generate the SH signal after being exposed to femtosecond infrared laser irradiation in the spectral range of 800-1020 nm. The stable enhancement of SHG induced by laser exposure can be attributed to the functional modifications of the Si NW surface, which can be used for the development of efficient nonlinear platforms based on silicon. This study delivers a valuable contribution to the advancement of optical devices based on silicon and presents novel design and fabrication methods for infrared converters.

Laser induced generation of hydrogen by using NdAlO3 nanocrystals as photocatalysts in alcohols

Laser Induced White Emission (LIWE) using focused infrared laser beam can emit hot electrons and, for this reason, has been described as capable of generating H2. NdAlO3 is described as a photocatalyst for H2 production in several alcohols using a focused 808 nm excitation; the process generated a low concentration of CH4 and no presence of carbon dots in the final solution, improving previous results using graphene foam. The proposed mechanism involves the ejection of hot electrons from the material and their subsequent absorption by the alcohol, ultimately leading to dehydrogenation. Besides that, relative permittivity was correlated with the amount of electrons emitted, which was demonstrated by a superb correlation between H2 production and relative permittivity of the media used. Higher relative permittivity media was able to emit more hot electrons, which ultimately produced more H2.

Development of Three-Dimensional Breast Scan and Measurement Application Using Laser Imaging Detection and Ranging Sensor on iPhone.

Laser imaging detection and ranging (LiDAR) is a modern three-dimensional (3D) technology that uses a time-of-flight method based on the round-trip time of an infrared laser beam to detect the presence and features of objects. The iPhone 12 Pro is the first smart mobile device with built-in LiDAR sensors. The authors' team developed a software application based on iOS devices with built-in LiDAR sensors for 3D breast scanning and automatically analyzing the breast's geometric measurement. Breast geometry, including midclavicle-to-nipple distance, sternal notch-to-nipple distance, nipple-to-inframammary fold (IMF) distance, distance between nipples, and body circumference on nipple and IMF level were measured using the software application and tapeline. The relative technical error of measurement (rTEM) value was used to calculate the error ratios between the measurements acquired by the software application and those of the tapeline. Good rTEM values ranging from 2.99% to 5.19% were found in the midclavicle-to-nipple distance, sternal notch-to-nipple distance, distance between nipples, nipple-level circumference, and IMF-level circumference. However, there was a poor rTEM value greater than 10% in the nipple-to-IMF distance. The proposed software application using current iOS devices with built-in LiDAR sensors can provide an ideal 3D scanning system that has a low cost burden, good accuracy, portability, and ease of use.

Design and characterisation of the JadePix-3 CMOS pixel sensor

The JadePix-3 CMOS pixel sensors have been developed and studied with a design optimised for a high position resolution of 3μm, which is one of the key requirements for the physics programmes at the Circular Electron-Positron Collider (CEPC) experiments. The sensors are orientated to the vertex detector for the experiments at the proposed future CEPC. The sensors with high-resistance substrates were produced using Tower Semiconductor’s 180 nm CMOS Imaging Sensor (CIS) process, which feature small sensing diodes, low power analogue front-ends with an in-pixel discriminator, and a rolling shutter readout scheme to minimise the pixel pitch. In the sensors, the pixel matrix of 512 rows × 192 columns is divided into four sectors with varied pixel size (16μm×26μm and 16μm×23.11μm) and circuit design. Electrical pulse tests reveal that for various sectors, the minimum thresholds range from 90 to 140 e, with a noise hit rate below an upper limit of 1 × 10−10/frame/pixel. An infra-red laser beam and a radioactive source of 90Sr have been used to characterise the sensors. The tests show that with the equivalent threshold charge fixed to 220 e−, a position resolution between pitch/212 and pitch/12 can be achieved by tuning the laser power for a signal charge between 440 e− and 880 e−. The measured power consumption is 127 mW for the JadePix-3 sensor and 87 mW/cm 2 when extrapolated to a large sensor of 1 cm × 2.5 cm.

Characterization of laser-induced shock waves generated during infrared laser ablation of copper by the optical beam deflection method

The shock waves generated during laser ablation of a copper target are investigated using the optical beam deflection method. The fluence of nanosecond pulsed infrared laser beam was in the range of 15-700J/cm2. The density jumps related with the influx of the shock wave at two interaction points were detected with the help of He-Ne laser probes. In general, a supersonic shock wave is produced, which propagates through air and gradually decays into an acoustic wave. Experiments were carried out to study the impact of laser fluence and propagation distance on the shock wave velocity and pressure. The shock wave velocity varies with laser fluence as v∝Fl0.3 and with propagation distance as v∝d-1.5. These results are compared with the predictions of the theoretical models. In the investigated fluence range, shock wave pressure rises by an order of magnitude (∼1-10MPa). We demonstrated that shock wave pressure and ablated mass can be related, yielding mass-specific shock wave pressure that increases linearly with laser fluence. We have also noticed the shock-wave-induced probe beam focusing under certain conditions, which indicates that the shock wave modifies the refractive index of the compressed layer of air. The reported results are useful for the fundamental understanding and pave the way for new applications of laser-induced shock waves.

Directly Mapping the Spatial Distribution of Organic Compounds on Mineral Rock Surfaces by DESI and LAESI Mass Spectrometry Imaging.

Here, we present a new application of desorption electrospray ionization (DESI) and laser ablation electrospray ionization (LAESI) mass spectrometry imaging to assess the spatial location of organic compounds, both polar and nonpolar, directly from rock surfaces. Three carbonaceous rocks collected from an aquatic environment and a berea sandstone subjected to a small-scale oil recovery experiment were analyzed by DESI and LAESI. No rock pretreatment was required before DESI and LAESI analyses. DESI detected and spatially mapped several fatty acids and a disaccharide on the surfaces of carbonaceous rocks, and various nitrogenated and oxygenated compounds on the surfaces of berea sandstone. In contrast, LAESI using a 3.4 μm infrared laser beam was able to detect and map hydrocarbons on the surfaces of all rock samples. Both techniques can be combined to analyze polar and nonpolar compounds. DESI can be used first to detect polar compounds, as it does not destroy the rock surface, and LAESI can then be used to analyze nonpolar analytes, as it destroys a layer of the sample surface. Both techniques have the potential to be used in several scientific areas involving rocks and minerals, such as in the analysis of industry-derived contaminants in aquatic sediments or in small-scale rock-fluid interaction experiments.

Investigations on laser beam welding of thin foils of copper and aluminum regarding weld seam quality using different laser beam sources

Nowadays, there is a strong and growing ambition to switch from combustion technology to battery-electric drives, and energy storage is spotlighted. Laser beam welding is an appropriate and favorable welding technology in battery production. Due to the high welding speed, the local heat input, the contact freeness efficient, and automatable processes can be established. Materials used in batteries for electrodes that have to be connected are commonly copper and aluminum. Specifically, copper is highly reflective for widely used infrared laser beam wavelengths. Furthermore, the thickness in the area of 10 μm is quite challenging to deal with, in terms of gap free clamping and avoidance of damage to the material as well as distortion during welding. There is a fine line regarding energy input between burning the material and generating a lack of fusion. In the presented research, welding approaches with different laser beam sources emitting laser beams with infrared wavelengths, various beam shapes, and welding modes (continuous and pulsed) are studied. A total of 40 copper foils with a thickness of 10 μm and 40 aluminum foils with a thickness of 15 μm are welded to similar sheet metals. Aim of the process development are welds with high quality and high connection widths to provide the best electric conductivity.

Evaluation and Manipulation of Neural Activity using Two-Photon Holographic Microscopy.

Recent advances in optical bioimaging and optogenetics have enabled the visualization and manipulation of biological phenomena, including cellular activities, in living animals. In the field of neuroscience, detailed neural activity related to brain functions, such as learning and memory, has now been revealed, and it has become feasible to artificially manipulate this activity to express brain functions. However, the conventional evaluation of neural activity by two-photon Ca2+ imaging has the problem of low temporal resolution. In addition, manipulation of neural activity by conventional optogenetics through the optic fiber can only simultaneously regulate the activity of neurons with the same genetic background, making it difficult to control the activity of individual neurons. To solve this issue, we recently developed a microscope with a high spatiotemporal resolution for biological applications by combining optogenetics with digital holographic technology that can modify femtosecond infrared laser beams. Here, we describe protocols for the visualization, evaluation, and manipulation of neural activity, including the preparation of samples and operation of a two-photon holographic microscope (Figure 1). These protocols provide accurate spatiotemporal information on neural activity, which may be useful for elucidating the pathogenesis of neuropsychiatric disorders that lead to abnormalities in neural activity.