Types Of Laser Sources Research Articles

High-throughput cell optoporation system based on Au nanoparticle layers mediated by resonant irradiation for precise and controllable gene delivery

The development of approaches based on genetically modified cells is accompanied by a constant intensive search for new effective and safe delivery systems and the study of existing ones. Recently, we developed a new plasmonic nanoparticle layers-mediated optoporation system that can be proposed for precisely controlled, high-performance laser transfection compatible with broad types of cells and delivered objects of interest. The main goal of the present study is to demonstrate the broad possibilities and advantages of our system for optoporation of several mammalian cells, classified as "easy-to-transfect" cells, namely HeLa and CHO lines, and "hard-to-transfect" cells, namely A431 and RAW 264.7 cells. We show the efficient delivery of various sized cargo molecules: from small molecular dyes propidium iodide (PI) with molecular mass 700 Da, control plasmids (3–10 kb) to fluorophore-labeled dextranes with masses ranging from 10 kDa up to 100 kDa. The performance of optoporation was investigated for two types of laser sources, 800-nm continuous-wave laser, and 1064-nm ns pulsed laser. We provided a comparative study between our system and commercial agent Lipofectamine for transient transfection and stable transfection of HeLa cells with plasmids encoding fluorescent proteins. The quantitative data analysis using flow cytometry, Alamar blue viability assay, and direct fluorescence microscopy revealed higher optoporation efficacy for hard-to-transfect A431 cells and Raw 264.7 cells than lipofection efficacy. Finally, we demonstrated the optoporation performance at the single-cell level by successful delivering PI to the individual CHO cells with revealed high viability for at least 72 h post-irradiation.

Supercontinuum Shaping via Hollow Core Anti-Resonant Fiber

This study proposes a novel supercontinuum (SC) shaping method using an all-fiber structure with little influence on the time domain and frequency domain of the SC spectrum. An SC is a type of laser source with a broad spectrum. However, its pump wavelength has a much greater intensity than other wavelengths, limiting the application of the SC. Our approach takes advantage of a hollow core anti-resonance fiber to attenuate the power density at the pump wavelength appropriately, thus flattening the SC spectrum. Simulation and experimental results both support the effectiveness of this method in reducing the wavelength at the pump. In our experiment, the use of a hollow core anti-resonant fiber decreased the intensity at the pump wavelength of the SC by 9 dB. By employing this method, the energy threshold can be lowered, allowing the SC to be applied to a larger range of experimental setups or applied scenarios with fewer energy requirements.

Stable cladding of high reflectivity pure copper on the aluminum alloy substrate by an infrared-blue hybrid laser

• A coaxial infrared-blue hybrid laser was adopted in cladding pure copper on the AlSi7M-g alloy substrate, which can make up for the forming instability of infrared laser and blue laser. • Hybrid laser can bring about a larger molten pool size, a slower cooling rate and a coarser microstructure. • The improvement in cladding stability under hybrid laser is closely related to the great increase in total laser absorption rate of the high reflectivity alloy and the reduction in fluctuation of absorption rate. A coaxial infrared-blue hybrid laser system was adopted in the cladding of high reflectivity pure copper on an AlSi7Mg alloy substrate, and the cladding stability, molten pool size and microstructure of the cladded samples by three types of laser sources (infrared, blue and their hybrid sources) were compared. The infrared-blue hybrid laser was validated to compensate for the forming instability of a high-power infrared laser and a low-power density blue laser. In addition, the heat accumulation in the cladding process with the hybrid laser was more obvious and the cooling rate was slower (1.36 × 10 4 K/s), which led to a coarser microstructure (1.56∼2.42 μm). Therefore, the hybrid laser can bring about stability and a larger molten pool size in cladding pure copper on the aluminum substrate, which is closely related to the great increase in the total laser absorption rate of the high reflectivity alloy and the reduction in the fluctuation of the absorption rate.

Analysis of the process of laser ablation of marble surfaces

Over the last decade, laser surface treatment of stones has gained increasing scientific interest. New technologies and processes based on different types of laser sources and processing modes are being studied. This report examines the process of laser ablation of a marble surface using a fiber laser. Three factors influencing the process of laser marking and engraving were studied: laser power, processing speed and step between raster lines. The functional dependencies between these factors and the contrast of the obtained graphic image are established. The optimal operating intervals for this group of technological parameters are analyzed. Thanks to the very-high-definition laser ablation, inscriptions, drawings and images can be re-created and processed with unique accuracy. In addition, the reduction of manufacturing time and resources used in the process makes this technology an environmentally-friendly and extremely cost-efficient solution.

Study on the Free Electron Laser and Condensed Matter Physics based on Computer

With the rapid development of computer technology, laser has been widely used in various fields of scientific research. However, with the development of computer technology, the shortcomings of traditional lasers are more and more obvious. Generally, lasers only work in different wavebands, which can not adjust the laser energy. Therefore, the peak power and average power of the laser are not high. The output power of different wavebands varies greatly, which increases the omplexity of the experiment. Therefore, the low power and non adjustable frequency limit the depth and breadth of application. In the dynamics study of condensed matter physics, the energy of many elementary excitations in condensed matter, such as acoustic phonon, magneton, polaron and so on, is in the far-infrared region. In recent years, a new type of laser source, free electron laser (FEL), with adjustable frequency and high power, has been developed in the world, which opens up a new way for the study of condensed matter physics. Firstly, this paper analyzes the related concepts. Then, the classification of FEL is analyzed. Finally, the application of FEL in condensed matter physics is proposed.

Thermal modeling of laser surface micro-texturing: Investigation on effects of laser parameters on dimple-texture dimensions and aspect ratio

Micro-texturing on the rake/flank face of the tool to obtain higher service life has emerged as a promising area of research. Micro-texturing assists in reducing contact area, and in-turn lowering wear and frictional heat. There are several methods to obtain micro-textures on tools. However, the quality of micro-texture depends largely on the manufacturing method used. Laser-induced surface texturing has been found more accurate and a cost-effective solution to enhance tribological properties and efficiency of the cutting tool. Ultra-short laser pulses can produce controlled ablation and micro-textures. However, obtaining accurate and ultra-clean micro-textures on cutting tools depends on the type of laser source, set of laser process parameters, and physical and mechanical properties of the cutting tool material. Several ablation models have been developed to predict the optimized set of laser parameters. This paper illustrates the simulation of laser surface texturing with the help of the finite element model and its experimental validation with a fiber laser. Thermal modeling and 2-D laser ablation have been presented for tungsten carbide (WC) tool material. Dimple textures have been created on the side rake face with equidistant spacing. Laser parameters like frequency and power have been varied to investigate their effect on texture dimensions and aspect ratio. Sample experimental validation results have also been discussed presenting the degree of agreement to simulation results.

The magnetic switch manufacturing by using ferrofluid and ferrofluid doped copper nanoparticles

In this work, a magnetic switch was prepared using two typesof ferrofluid materials, the pure ferrofluid and ferrofluid doped with copper nanoparticles (10 nm). The critical magnetic field (Hc) and the state of magnetic saturation (Hs) were studied using three types of laser sources. The main parameters of the magnetic switch measured using pure ferrofluid and He-Ne Laser source were Hc(0.5 mv, 0.4 G), Hs (8.5 mv, 3 G). For the ferrofluid doped with copper nanoparticles were Hc (1 mv, 4 G), Hs (15 mv, 9.6 G), Using green semiconductor laser for the Pure ferrofluid were Hc (0.5 mv, 0.3 G) Hs (15 mv, 2.9 G). While the ferrofluid doped with copper nanoparticles were Hc (0.5 mv, 1 G), Hs (12 mv, 2.8 G) and by using the violet semiconductor laser the pure ferrofluid parameters were Hc(0.5 mv, 0.5 G), Hs (15 mv, 3.5 G) while the ferrofluid doped with coppernanoparticles are Hc (0.5 mv,1 G), Hs (15 mv, 3.3 G).

Optical and structural changes of TiO2/PVA nanocomposite induced laser Radiation

The laser irradiation effect of on the structural and optical properties of TiO2/PVA nanocomposite at different loading of TiO2 nanoparticles as (1.25%, 2.5%, 5%, 7.5%, 10% TiO2 /PVA) was investigated. Two different types of laser sources were used Nd: YAG laser (at 266nm) and Nitrogen laser at (337nm). The XRD, FTIR and UV-Visible are used to reveal the structural changes and the optical parameters of the composites due to the laser irradiation. Changes of the crystalinity of the composites films were observed by XRD, where the Nd: YAG laser developed a decrease in the crystalinity of all the investigated samples, while the Nitrogen laser developed an increase of the crystalinity. IR spectroscopy showed strong reduction of –OH group as a result of both lasers. It also shows an increase in the intensity of the vibration modes at 1720cm−1 corresponding to carbonyl formation due to the effect of Nd: YAG laser irradiation only. The intensity of the C-C bond increases after Nitrogen laser irradiation indicating the increase of crystalinity of the composites films. UV-Vis spectra indicates the photothermal effect of Nitrogen laser and the photochemical effect of Nd: YAG laser. The optical constant of the all composites samples have been calculated before and after irradiation with both two types of laser sources which coincide with the results obtained from XRD and IR studies.

Direct generation of superhydrophobic microstructures in metals by UV laser sources in the nanosecond regime

Abstract The current availability of new advanced fiber and DPSS lasers with characteristic pulse lengths ranging from ns to fs has provided a unique frame in which the development of laser-generated microstructures has been made possible for very diverse kinds of materials and applications. At the same time, the development of the appropriate laser-processing workstations granting the appropriate precision and repeatability of the respective laser interaction processes in line with the characteristic dimension features required in the microstructured samples has definitively consolidated laser surface microstructuring as a reference domain, nowadays, unavoidable for the design and manufacturing of current use microsystem: MEMSs, fluidic devices, advanced sensors, biomedical devices and instruments, etc., are all among the most well-known developments of the micromanufacturing technology. Completing the broad spectrum of applications developed mostly involving the generation of geometrical features on a subtrate with specific functional purposes, a relatively new, emerging class of laser-microstructuring techniques is finding an important niche of application in the generation of physically structured surfaces (particularly of metallic materials) with specific contact, friction, and wear functionalities, for whose generation the concourse of different types of laser sources is being found as an appropriate tool. In this paper, the application of laser sources with emission in the UV and at ns time regime to the surface structuration of metal surfaces (specifically Al) for the modification of their wettability properties is described as an attractive application basis for the generation of self-cleaning properties of extended functional surfaces. Flat aluminum sheets of thickness 100 μm were laser machined with ultraviolet laser pulses of 30 ns with different laser parameters to optimize the process parameters. The samples produced at the optimum conditions with respect to contact angle measurement were subjected to microstructure and chemical analysis. The wetting properties were evaluated by static contact angle measurements on the laser-patterned surface. The laser-patterned microstructures exhibited superhydrophobicity with a maximum contact angle of 180° for the droplet volumes in the range of 8–12 μl.

Theoretical study on temperature features of a sealed cesium vapor cell pumped by laser diodes.

The diode-pumped alkali laser (DPAL) is a new type of laser source which has been widely studied in the recent years. The temperature distribution of a sealed vapor cell, which is the crucial component in a DPAL system, produces an important effect on the output performance of a DPAL. In this paper, the strict solution of the heat conduction equation for a cesium vapor cell is obtained by using a finite difference procedure. The temperature distribution of a dummy open cell is first analyzed, and then the temperature distributions of two independent windows, regarded as the boundary conditions of solving a sealed cell, are evaluated in detail. By combining the results of the two steps together, we finally acquire the temperature distribution of a real sealed cesium vapor cell. The results reveal that the temperature gradients on both radial and longitudinal directions change with the pump power, cell radius, and absorption coefficient when the sealed cesium vapor cell is heated or pumped with the laser diodes. The conclusions are helpful for accurately evaluating the output characteristics of a DPAL.

Laser Transmission Welding of White Thermoplastics with Adapted Wavelengths

Different types of laser sources can be used for polymer welding. By the principle of laser transmission welding the wavelength of the laser is one of the most important criteria when selecting a laser source as the optical properties of the polymers are depending on the wavelength. Up to date white material cannot be welded to each other. The results show that by analysis of the optical properties, especially the absorption and the scattering coefficient and adaption of the laser wavelength the process limits can be extended.

Laser induced simultaneous etching of silicon and deposition of carbon materials

Silicon (100) substrates have been irradiated in a gaseous atmosphere of diiodo-methane (CH2I2) by employing two different types of laser sources. Either focused 248nm excimer laser pulses or 532nm cw laser radiation have been used. Below the melting temperature of Si, complex etching of Si and deposition of carbon appear simultaneously only for irradiation with 248nm. Above the Si-melting point, the precursor allows efficient etching of Si with a simultaneous deposition of carbon materials for both wavelengths. In particular with focused 532nm radiation high processing rates and aspect ratios of the structures can be achieved.

Impact of Backreflections on Single-Fiber Bidirectional Transmission in WDM-PONs

We analyze the system impairment due to beat noises between backreflections and the upstream signal in bidirectional single-fiber wavelength-division-multiplexing passive optical networks (WDM-PONs). The relative intensity noise (RIN), the power penalty caused by the beat noises and the optimum optical network unit (ONU) gain that minimizes this penalty are investigated. In addition to the transmission line loss (TLL), we find that these parameters are also dependent on the linewidth of the seed light, the chirp effect at the ONU and the receiver bandwidth. Different types of laser sources at the optical line terminal (OLT) and various wavelength-independent ONU configurations are intensively investigated to explore those dependencies. It is also found that the systems with remodulation configurations are more tolerant to the backreflections.

Gas chromatography/multiphoton ionization/time-of-flight mass spectrometry of polychlorinated biphenyls

A sample mixture of polychlorinated biphenyls (PCBs) was measured by gas chromatography/multiphoton ionization/time-of-flight mass spectrometry (GC/MPI/TOF-MS) using four types of laser sources. When a fourth harmonic emission (266 nm) of a picosecond Nd:YAG laser (1064 nm) was utilized, highly chlorinated PCBs larger than hepta-CBs were not observed. A fifth harmonic emission (213 nm) of the picosecond Nd:YAG laser allowed the measurement of PCBs from di-CBs to octa-CBs, and the limit of detection (LOD) was several pg for each component of PCBs. The LOD for the total amount of PCBs, which was calculated using the protocol provided by the Ministry of the Environment, Japan, was 1000 pg. The signal intensity of the congeners with chlorine atoms at the ortho positions (non-coplanar PCBs) was enhanced by using the fifth harmonic emission. When the fourth harmonic emission remaining after fifth harmonic generation was simultaneously used, the LOD for total PCBs was improved to 667 pg. The PCB sample was also measured using a third harmonic emission (267 nm) of a femtosecond Ti:sapphire laser (800 nm), providing an LOD of 677 pg. Thus, the two-color beam (266/213 nm) of a picosecond Nd:YAG laser had a comparable, or even slightly superior, performance to the more expensive femtosecond Ti:sapphire laser.

Analysis of Dioxins by Gas Chromatography/Resonance-Enhanced Multiphoton Ionization/Mass Spectrometry Using Nanosecond and Picosecond Lasers

Dioxins in a soil sample were measured using gas chromatography/resonance-enhanced multiphoton ionization/time-of-flight mass spectrometry coupled with different types of laser sources. The fourth-harmonic emission (266 nm) of a nanosecond Nd:YAG laser (1 ns) provided low ionization efficiency, especially for highly chlorinated dioxins/dibenzofurans (CDDs/CDFs). The ionization efficiency was improved using the fourth-harmonic emission (266 nm) of a picosecond Nd:YAG laser (4 ps), due to shorter singlet excited-state lifetimes. It was, however, difficult to efficiently ionize hepta-CDD and octa-CDD/CDF, because of their shorter lifetimes, which were induced by stronger spin-orbit coupling that led to efficient relaxation of the excited molecule to triplet levels. The ionization efficiency was substantially improved using the fifth-harmonic emission (213 nm) of the picosecond Nd:YAG laser (4 ps), in which the analyte molecule that was relaxed to triplet levels was efficiently ionized using a photon with sufficient energy for ionization, although the pulse energy obtained at 213 nm was only one-third of the pulse energy obtained at 266 nm. The limits of detection achieved for 17 toxic polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDDs/PCDFs) were 0.41-45 pg. The analytical instrument developed in the present study performed sufficiently well for the practical trace analysis of dioxins in soil samples.

A Fiber Optic Doppler Sensor and Its Application in Debonding Detection for Composite Structures

Debonding is one of the most important damage forms in fiber-reinforced composite structures. This work was devoted to the debonding damage detection of lap splice joints in carbon fiber reinforced plastic (CFRP) structures, which is based on guided ultrasonic wave signals captured by using fiber optic Doppler (FOD) sensor with spiral shape. Interferometers based on two types of laser sources, namely the He-Ne laser and the infrared semiconductor laser, are proposed and compared in this study for the purpose of measuring Doppler frequency shift of the FOD sensor. Locations of the FOD sensors are optimized based on mechanical characteristics of lap splice joint. The FOD sensors are subsequently used to detect the guided ultrasonic waves propagating in the CFRP structures. By taking advantage of signal processing approaches, features of the guided wave signals can be revealed. The results demonstrate that debonding in the lap splice joint results in arrival time delay of the first package in the guided wave signals, which can be the characteristic for debonding damage inspection and damage extent estimation.

Frequency-domain photothermoacoustic imaging contrast enhancement with a CW laser and non-linear frequency modulation chirps

The application of photoacoustic (PA) phenomena to medical imaging has been investigated for more than a decade. To implement this modality, one may choose between two types of laser sources, pulsed or continuous wave (CW). This selection will affect all features of the imaging technique. Nowadays pulsed lasers are the state-of-the-art technique in the PTA research. In this work we report frequency-domain photothermoacoustic imaging using linear and non-linear frequency chirps with a CW laser. The images produced using turbid tissue phantoms with subsurface inclusions were compared according to their contrast and depth resolution of absorbing lesions. In the CW method, in addition to the image produced by the amplitude of the cross-correlation between input and output signals, another image which is generated by the phase of the correlation signal is also available. The application of nonlinear frequency modulation instead of the standard linear frequency chirps introduced in our laboratory is demonstrated. These features are additional degrees of freedom uniquely available to the CW (but not to the pulsed laser) method.

Influence of laser sources with different spectral properties on the performance of vapor cell atomic clocks based on lin‖lin CPT

We evaluate the influence of 2 types of laser sources with different spectral profiles on the performance of vapor cell atomic clocks based on lin||lin coherent population trapping (CPT) resonances. We show that a short-term stability of 1-2 x 10(-11) tau(-1/2) may be reached in a compact system using a modulated vertical cavity surface-emitting laser. Here the stability is limited by the detection noise level and can be improved up to a factor of 4 by increasing the lock-in detection frequency to several tens of kilohertz, which is not possible in standard double resonance atomic clocks. We compare these results with CPT prepared under the same experimental conditions, using 2 phase-locked extended cavity diode lasers, with which we predict a challenging short-term stability of 1-3 x 10(-13) tau(-1/2), comparable to the state-of-the-art laser-pumped Rb-clocks.

Light emission: A temperature-tunable random laser.

Random lasers have fascinating emission properties that lie somewhere between those of a conventional laser and a common light-bulb. We have created a random laser that can be brought above and below its threshold for laser emission by small changes in its temperature, thereby creating a light source with a temperature-tunable colour spectrum. As a single random laser can be made as small as a grain of tens of micrometres in diameter, we expect our device to find application in photonics, temperature-sensitive displays and screens, and in remote temperature sensing. Lasers are now commonplace - for example, they are used in industry and in hospitals, in bar-code scanners and compact-disc players. Conventional lasers are based on an optically active material and some sort of laser cavity that traps light for long enough for laser action to occur. A new type of laser source, known as a random laser, has been discovered that does not require a regular cavity but instead depends on a diffusive material such as a fine powder. In a random laser, light waves are trapped by multiple light scattering (that is, light diffusion), which takes over the role of the cavity in a regular laser (Fig. 1). The emission of a random-laser source has a well defined colour spectrum and can be pulsed, just like a regular laser, although its emission is in several directions because of the intrinsic randomness of the system.

Laser surface cleaning, de-rusting, de-painting and de-oxidizing

Many materials have been tested as substrates and surface products. Typically ferrous (Carbon Steels and Stainless Steels) and non-ferrous (Al and Cu metals and its alloys) materials have been employed. Some epoxy, polyurethane, polyester and acrylic paints with different thickness and colour have been tested. Many types of surface rust and oxide on different bulk material have been undertaken to test. Similarly, some different types of oils and greases commonly used in industry to prevent oxidation, have been studied. Different types of laser sources have been employed: an axial fast flow, 1.5 kW CO2 c.w. and pulsed laser source emitting a 10.6 μm beam; and a portable Nd:YAG laser, Q-switchedand normal-mode source: 1st harmonic 1.064 μm (6 ns pulse duration), 2nd harmonic 532 nm (120 μs duration pulse, 1 J max per pulse) wavelengths, multi-articulated seven mirror beam guiding device, 20 Hz repetition rate. This provides shots with 600 mJ maximum energy per pulse and 100 MW peak power per pulse with very low beam divergence: 0.5 mrad at full angle.