Laser Radiation Research Articles

A Comprehensive Systematic Review of the Effects of Photobiomodulation Therapy in Different Light Wavelength Ranges (Blue, Green, Red, and Near-Infrared) on Sperm Cell Characteristics in Vitro and in Vivo.

Around 7% of the male population in the world are entangle with considerable situation which is known as male infertility. Photobiomodulation therapy (PBMT) is the application of low-level laser radiation, that recently used to increase or promote the various cell functions including, proliferation, differentiation, ATP production, gene expressions, regulation of reactive oxygen spices (ROS), and also boost the tissue healing and reduction of inflammation. This systematic review's main idea is a comprehensive appraisal of the literatures on subjects of PBMT consequences in four light ranges wavelength (blue, green, red, near-infrared (NIR)) on sperm cell characteristics, in vitro and in vivo. In this study, PubMed, Google Scholar, and Scopus databases were used for abstracts and full-text scientific papers published from 2003-2023 that reported the application of PBM on sperm cells. Criteria's for inclusion and exclusion to review were applied. Finally, the studies that matched with our goals were included, classified, and reported in detail. Also, searched studies were subdivided into the effects of four ranges of light irradiation, including the blue light range (400-500 nm), green light range (500-600 nm), red light range (600-780 nm), and NIR light range (780-3000 nm) of laser irradiation on human or animal sperm cells, in situations of in vitro or in vivo. Searches with our keywords results in 137 papers. After primary analysis, some articles were excluded because they were review articles or incomplete and unrelated studies. Finally, we use the 63 articles for this systematic review. Our category tables were based on the light range of irradiation, source of sperm cells (human or animal cells) and being in vitro or in vivo. Six% of publications reported the effects of blue, 10% green, 53% red and 31% NIR, light on sperm cell. In general, most of these studies showed that PBMT exerted a positive effect on the sperm cell motility. The various effects of PBMT in different wavelength ranges, as mentioned in this review, provide more insights for its potential applications in improving sperm characteristics. PBMT as a treatment method has significant effectiveness for treatment of different medical problems. Due to the lack of reporting data in this field, there is a need for future studies to assessment the biochemical and molecular effects of PBMT on sperm cells for the possible application of this treatment to the human sperm cells before the ART process.

Interference mechanism of plasma self-organization in transparent dielectrics under the intense femtosecond laser pulse exposure

A new mechanism of plasma self-organization in transparent dielectrics with wide bandgap exposed to the intense tightly focused laser radiation was revealed, which causes the generation of 3D periodic ring structures with subwavelength period both along the laser pulse propagation and in the radial direction. The mechanism involves formation of dense plasma burst in the pre-focal region that provides efficient scattering of the incident wave. The interference of a plane incident laser wave in the focal region and a divergent reflected one will form the standing wave pattern with local minima and maxima of laser field both in the direction of the incident wave propagation and perpendicular to it producing the ring patterns of effective ionization regions in the dielectric volume. Analytical and numerical simulations of the process of laser wave scattering on a near-spherical plasma object with dimensions both smaller and larger than the laser radiation wavelength are performed to verify the proposed model.

Exploring the effect of thin film thicknesses on linear and nonlinear optical properties of MoO3 thin film

The structural, morphological, linear, and nonlinear optical properties of MoO3 thin films deposited by thermal deposition were measured. The effect of various thicknesses of films was studied. The structural and morphological parameters of films, determined by x-ray diffraction, field emission scanning electron microscopy, and AFM images, are compared to the linear and nonlinear optical characteristics of these media. The bandgap of the prepared thin films was obtained from the diffuse reflectance spectroscopy spectra. The electron’s effective mass (me*/m0), linear refractive index (n0), and optical static and high frequency dielectric constant (ɛ0, ɛ∞) values were calculated by using the bandgap energy values. Increasing the thicknesses of thin films decreased the bandgap, increased the root mean square, and increased the size of nanoparticles and the nonlinear response of thin films. The high magnitude of n2 and β was because of MoO3 (300 nm-thickness), which were of the order of 10−5 cm2/W and 10−1 cm/W, respectively. The fluctuations in nonlinear responses observed at different thicknesses are attributed to d–d transitions and intraband scattering of equilibrium electrons influenced by laser radiation, as indicated by the nonlinearity data. The considerably elevated refractive nonlinearity values in the analyzed film materials suggest their potential for practical application in optoelectronic devices.

Optimization of Pump Pulse Duration and Cr:ZnSe Crystal Length for Efficient Generation of Tunable Mid-IR Laser Radiation Pumped by Laser Diode at Room Temperature

Optimization of Pump Pulse Duration and Cr:ZnSe Crystal Length for Efficient Generation of Tunable Mid-IR Laser Radiation Pumped by Laser Diode at Room Temperature

Регенерация волоконных брэгговских решеток, записанных поточечным методом с помощью излучения фемтосекундного лазера

The relevance of studies on the thermal stability of fiber Bragg gratings arises from the prospects of their applications in difficult operating conditions at elevated temperatures. One of the highest-temperature types of such structures formed in silica glass fibers are regenerated Bragg gratings. Generally, the regeneration effect is observed in gratings inscribed in molecular hydrogen-loaded fibers and/or in highly-doped germanosilicate fibers. This paper describes the first reported regeneration of gratings created via point-by-point inscription with femtosecond laser radiation in standard telecommunication fiber Corning SMF-28 without the presence of hydrogen in technological processes. The paper proposes an explanation of the possible mechanism for the formation of such regenerated structures.

Optical parameters of healthy and tumor breast tissues in mice.

Knowledge of the optical parameters of tumors is important for choosing the correct laser treatment parameters. In this paper, optical properties and refraction indices of breast tissue in healthy mice and a 4T1 model mimicking human breast cancer have been measured. A significant decrease in both the scattering and refractive index of tumor tissue has been observed. The change in tissue morphology has induced the change in the slope of the scattering spectrum. Thus, the light penetration depth into tumor has increased by almost 1.5-2 times in the near infrared "optical windows." Raman spectra have shown lower lipid content and higher protein content in tumor. The difference in the optical parameters of the tissues under study makes it possible to reliably differentiate them. The results may be useful for modeling the distribution of laser radiation in healthy tissues and cancers for deriving optimal irradiation conditions in photodynamic therapy.

Quantum Theory of the Effect of Increasing Weak Electromagnetic Wave by a Strong Laser Radiation in 2D Graphene

Quantum Theory of the Effect of Increasing Weak Electromagnetic Wave by a Strong Laser Radiation in 2D Graphene

Анализ течений при лазерно-акустической обработке нержавеющей стали AISI 316L

The influence of ultrasonic vibrations on the flow of molten metal during laser processing is investigated. This problem is of interest within the context of modernization of existing technological processes, such as laser welding and cladding, for the production of structures with improved physical and mechanical properties. The introduction of additional ultrasonic energy into the liquid metal bath intensifies the metal flow via forced stirring, which provides its homogenization and leads to an increase in the mechanical properties of the processed material due to the growth of the number of crystallization centers during its solidification. In order to get a better understanding of this combined process and to control it, a method for synthesizing hydrodynamic and strength solvers used in the ANSYS software package is proposed. Setting up the coupling between two corresponding ANSYS Transient Structural and ANSYS CFX modules is executed through the additional ANSYS System Coupling module. Under this numerical implementation of the problem, it is possible to calculate the displacements at the solid metal boundary and their transfer to the liquid metal boundary and vice versa at each moment of time. The impact of laser radiation on the liquid metal is considered taking into account Marangoni convection, and convection and radiation heat transfer. The results of numerical experiments make it possible to conduct a qualitative and quantitative comparison between the liquid AISI 316L stainless steel flows formed without and with ultrasonic vibration. It is shown that the intensification and deceleration of the flows is observed at the average values of the ultrasonic amplitude. This fact correlates with the moments of time at which the deformed surface of the metal in the bath moves down and up. A comparative analysis of the maximum axial velocities inside the liquid metal bath was conducted. The absence of ultrasonic action on the liquid metal motion was observed at the maximum values of the vibration amplitude, which correspond to the maximum displacement and deformation of the surface at the interface between liquid and solid.

Comparison of the Effectiveness of High Intensity Laser therapy (HILT) and Low-Level Laser Therapy (LLLT) on Functional Improvement in Knee Osteoarthritis Patients

BACKGROUND : Knee osteoarthritis causes sore, joint stilted, progressive deformity and functional encroachment. The current therapeutic focus on rectifying function and assuaging symptoms, especially pain. There are two types of laser therapy, namely Low-Level Laser Therapy (LLLT) and High Intensity Laser Therapy (HILT). High Intensity Laser Therapy (HILT) is a high-intensity laser radiation with photochemical, photothermal, and photomechanical action possess many therapeutic steads including analgesic, anti-edematous, and biostimulating effects. In this study, we compare the effectiveness of HILT with LLLT on functional enhancement in knee osteoarthritis assessed by the Knee Injury and Osteoarthritis Outcome Score (KOOS). AIMS : To compare the effectiveness of HILT with LLLT on functional enhancement in patients with knee osteoarthritis. METHOD : This research is a quasi-experimental pre-test and post-test with controlled group design. There were 27 subjects of knee osteoarthritis patients who were divided into 2 treatment groups, the first treatment group admit HILT therapy (14 patients) and the second treatment group admit LLLT therapy (13 patients). Knee Injury and Osteoarthritis Outcome Score (KOOS) was measured before and after 4 weeks of treatment. RESULT : There was a significant difference in the mean value of functional improvement as measured by KOOS before and after treatment in each group (p < 0.001) and there was a significant difference in the mean value of KOOS in the two groups (p < 0.001). CONCLUSION : The administration of HILT has shown significant escalation of functional improvement compared to the administration of LLLT in patients with knee osteoarthritis.

Effectiveness of therapy of complicated forms of dental caries using an Er,Cr:YSGG laser with a wavelength of 2780 nm

BACKGROUND: The use of laser technologies in the treatment of complicated forms of dental caries is promising in dentistry. However, the available literature does not fully cover the use of the Er,Cr:YSGG laser (wavelength: 2780 nm) in the treatment of purulent pulpitis and pulp necrosis. AIM: To determine the effectiveness of therapy for complicated forms of dental caries using an erbium–chromium laser with a wavelength of 2780 nm for biomechanical treatment of root canals. MATERIALS AND METHODS: Overall, 106 patients were examined and divided into three groups: group 1 (control), 15 patients whose treatment was performed using a generally accepted method; group 2, 50 patients who were treated with erbium–chromium laser radiation at the second visit, immediately before root canal obturation; and group 3, 41 patients who were treated in one visit and divided into two subgroups. In group 3-A (n=18), the root canal was irradiated with a laser with factory settings, and in group 3-B (n=23), the frequency and power of the laser were increased from 20 to 40 Hz and from 1.25 to 1.5 Watts, respectively. RESULTS: In group 1, 59 microorganisms from all 17 strains were seeded before the treatment of the root canal system of teeth with chlorine-containing disinfectants. Moreover, the proportion of seeded microorganisms in each strain was 6.6%–40% (average value: 23.1%). After treatment, the seeding rate of Streptococcus mitis decreased from 40% to 13%, Streptococcus intermedius from 20% to 6.6%, Enterococcus spp. from 33.3% to 13.3%, and Candida spp. from 33.3% to 20%. In group 2, after complex biomechanical treatment of root canals and the use of a hydrokinetic laser, none of the 17 strains sown before treatment were observed. The Candida spp. (5.5%) were not neutralized due to the use of a hydrokinetic laser with a wavelength of 2780 nm in the factory settings in group 3-A (power, 1.25 W; pulse frequency, 20 Hz; air, 10%; water, off). The combined use of the traditional protocol and hydrokinetic Er,Cr:YSGG laser in group 3B enabled complete elimination of microorganisms from those sown before treatment (p 0.001). CONCLUSION: Treatment of purulent pulpitis and pulp necrosis in one visit using a hydrokinetic Er,Cr:YSGG laser with a wavelength of 2780 nm with increased parameters (i.e., power, 1.5 W; frequency, 40 Hz; air, 35%; water, 25%) is recommended.

The Second Laser Revolution in Chemistry: Emerging Laser Technologies for Precise Fabrication of Multifunctional Nanomaterials and Nanostructures

AbstractThe use of photons to directly or indirectly drive chemical reactions has revolutionized the field of nanomaterial synthesis resulting in appearance of new sustainable laser chemistry methods for manufacturing of micro‐ and nanostructures. The incident laser radiation triggers a complex interplay between the chemical and physical processes at the interface between the solid surface and the liquid or gas environment. In such a multi‐parameter system, the precise control over the resulting nanostructures is not possible without deep understanding of both environment‐affected chemical and physical processes. The present review intends to provide detailed systematization of these processes surveying both well‐established and emerging laser technologies for production of advanced nanostructures and nanomaterials. Both gases and liquids are considered as potential reacting environments affecting the fabrication process, while subtractive and additive manufacturing methods are analyzed. Finally, the prospects and emerging applications of such technologies are discussed.

Online Raman spectroscopy for quantitative detection and characterization of aerosolized soot.

Ex-situ Raman spectroscopy is a well-established method for the structural characterization of soot but necessitates a sampling step before analysis is made. This work studied the potential to perform Raman spectroscopic measurements of soot directly in the combustion exhaust gases, i.e., online Raman measurements. Two types of soot were produced from a Mini-CAST soot generator, one immature with high organic content and one mature with low organic content. Also, two different measurement configurations were used, a 90-degree and a backscattering configuration, as well as different polarization combinations of the laser radiation and the detected photons. Spectrally resolved Raman signals were successfully recorded and analyzed for the two soot types showing differences between the characteristic D and G peaks as well as the photoluminescence signal. Additionally, the Raman cross section was determined for both soot types and found to be higher for the immature soot. It was also found that a horizontally polarized laser excitation and a 90-degree collection angle had the best potential to reduce the interference from ambient gases. This study can be seen as a first step towards remote sensing of soot.

Risks associated with laser radiation reflections in a healthcare environment: a surface reflectance study in the range 250 nm – 25 μm

Risks associated with laser radiation reflections in a healthcare environment: a surface reflectance study in the range 250 nm – 25 μm

Calibrating the global network of gravitational wave observatories via laser power calibration at NIST and PTB

Current gravitational wave (GW) observatories rely on photon calibrators that use laser radiation pressure to generate displacement fiducials used to calibrate detector output signals. Reducing calibration uncertainty enables optimal extraction of astrophysical information such as source distance and sky position from detected signals. For the ongoing O4 observing run that started on 24 May 2023, the global GW detector network is employing a new calibration scheme with transfer standards calibrated at both the National Institute of Standards and Technology (NIST) and the Physikalisch-Technische Bundesanstalt (PTB). These transfer standards will circulate between the observatories and the metrology institutes to provide laser power calibration traceable to the International System of Units (SI) and enable assessment and reduction of relative calibration errors for the observatory network. The Laser Interferometer Gravitational-Wave Observatory (LIGO) project and the Virgo project are currently participating in the new calibration scheme. The Large-scale Cryogenic Gravitational-wave Telescope project (KAGRA) is expected to join in 2024, with the LIGO Aundha Observatory in India joining later. Before implementing this new scheme, a NIST-PTB bilateral comparison was conducted. It validated the scale representation by both laboratories, with a degree of equivalence of −0.2% and an associated expanded uncertainty of 0.32% (k = 2) which is significantly lower than previous studies. We describe the transfer of power sensor calibration, including detailed uncertainty estimates, from the transfer standards calibrated by NIST and PTB to the sensors operating continuously at the interferometer end stations. Finally, we discuss the ongoing calibration of Pcal-induced displacement fiducials for the O4 observing run. Achieved combined standard uncertainty levels as low as 0.3% facilitate calibrating the interferometer output signals with sub-percent accuracy.

The bacterial flagellum as an object for optical trapping.

This letter considers the possibility of using the optical trap to study the structure and function of the microbial flagellum. The structure of the flagellum of a typical gram-negative bacterium is described in brief. A standard mathematical model based on the principle of superposition is used to describe the movement of an ellipsoidal microbial cell in a liquid medium. The basic principles of optical trapping based on the combined action of the light pressure and the gradient force are briefly clarified. Several problems related to thermal damage of living microscopic objects when the latter gets to the focus of a laser beam are shortly discussed. It is shown that the probability of cell damage depends nonlinearly on the wavelength of laser radiation. Finally, the model systems that would make it possible to study flagella of the free bacteria and the ones anchored or tethered on the surface of a solid material are discussed in detail.

Assessment of Surface Roughness of Non-Metallic Materials during Laser Processing

Experimental studies of the surface of non-metallic materials have been carried out to determine the roughness parameters of materials such as leather, bone, wood, plastic after processing the surface of materials with a laser beam. To assess the quality of the surface layer of materials, the depth of penetration of laser radiation into the material, the average value of the micro unevenness, and the mean square deviation of the micro unevenness were used. To describe the changes in the values of the micro unevenness, graphs of the correlation of the parameters of the micro unevenness and the modulus of elasticity of the surface of various non-metallic materials were used. Approximating polynomials are used to describe the correlations with the representation in a computer. A regression model is proposed that relates the properties of the material to the magnitude of the micro unevenness. Data on the depth of ablation for wood, bone, leather, plexiglass are presented, graphs of the correlation between the amount of surface micro unevenness and the density of materials, between the amount of surface micro-roughness and the modulus of elasticity of materials, the correlation coefficient between the amount of surface micro unevenness and the ignition temperature of organic materials. The obtained models make it possible to implement the proposed principle of laser processing of non-metallic materials, which consists in measuring the modulus of elasticity of the surface of the material and, based on the measurements obtained, control the modes of laser processing of products. The installation of laser surface treatment of non-metallic materials with the implementation of the principle of control of processing modes depending on the measured values of the modulus of elasticity of the surface of the material is proposed. To measure the elastic modulus of a material, a special sensor is used with indentation of the indenter and computer evaluation of the measurements obtained with the formation of solutions for controlling the modes of laser surface treatment of the material. The experimental results obtained made it possible to manufacture a number of products to ensure a given surface quality of non-metallic materials (a writing device, a gift for the newlyweds). Conducting experiments with changes in the power of laser radiation based on the results of measuring the modulus of elasticity of the surface of non-metallic materials has shown the effectiveness of operational setting of laser operating modes to ensure the quality of the surface of non-metallic materials.

New approaches in the tomographic visualization of joints using X-ray contrast nanoparticles and laser radiation

New approaches in the tomographic visualization of joints using X-ray contrast nanoparticles and laser radiation

On the Effect of Focusing Conditions on the Emission Capacity of a Laser-Plasma Ion Source

The issues of the influence of geometric conditions of laser radiation focusing on the surface of the plasma-forming target of an laser-plasma ion source are considered. In particular, the presence of two ion emission maxima in the region of the laser radiation flux density exceeding 1011 W/m2 has been experimentally established. A possible interpretation of this effect is proposed.

Conjugate Polymer Anchor Enhancing Matrix Vacuum Stability and Improving MALDI MSI via Ion Bond.

Poor vacuum stability limits the application of many matrices in matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) that requires long-term measurement duration in high vacuum. In this study, a new approach using conjugate polymer anchor to protect unstable matrix from volatilizing in MALDI source based on ion bond is provided. Unlike strong covalent bonds which often introduce unnecessary groups, the weaker ion bonds are more conducive to breaking under laser radiation while effectively preventing matrix volatilization in a vacuum environment. The results confirm that conjugate polymer anchor will neither introduce additional ion peaks nor affect signal intensity, yet maintains comparable quantification properties. Vacuum stability of three kinds of typical matrices is enhanced using polymer anchors, and the in situ MALDI MS imaging of mouse brain and liver cancer is improved significantly.

Reversible Laser Imprinting of Phase Change Photonic Structures in Integrated Waveguides.

Formation of laser-induced periodic surface structures (LIPSS) is known as a fast and robust method of functionalization of material surfaces. Of particular interest are LIPSS that manifest as periodic modulation of phase state of the material, as it implies reversibility of phase modification that constitute rewritable LIPSS, and recently was demonstrated for chalcogenide phase change materials (PCMs). Due to remarkable properties of chalcogenide PCMs─nonvolatality, prominent optical contrast and ns switching speed─such novel phase change LIPSS hold potential for exciting applications in all-optical tunable photonics. In this work we explore phase change LIPSS formation in thin films of Ge2Sb2Te5 (GST) integrated with planar and rib waveguides. We demonstrate that by fine-tuning laser radiation, the morphology of phase change LIPSS can be controlled, including their period and fill factor, and investigate the limitations of multicycle rewriting of the structures. We also demonstrate the formation of phase change LIPSS on a 1D waveguide, which has potential for use as tunable Bragg filters or structures for on-demand light decoupling into the far-field. The presented concept of applying phase change LIPSS offers a promising approach to enable fast and simple tuning in integrated photonic devices.