Gaussian Laser Beam Research Articles

Quadruple Gaussian laser beam in cubic-quintic nonlinear media: effect of nonlinear absorption

Quadruple Gaussian laser beam in cubic-quintic nonlinear media: effect of nonlinear absorption

Numerical Simulation of the Reflectance Signal from a Short-Pulse Gaussian Laser Beam Incident on Healthy and Malignant Skin Tissue

Numerical Simulation of the Reflectance Signal from a Short-Pulse Gaussian Laser Beam Incident on Healthy and Malignant Skin Tissue

Developing 3D computational models to capture the spatial, temporal and thermal behavior as laser beams propagate through photo-thermally responsive gels

Gaussian laser beams propagating through photo-thermally responsive gels exhibit self-trapping and attraction. Two beams can cross each other if the interaction is sufficiently strong.

A Numerical Approach for Predicting Temperature Distribution, Heat Flow, and Material Deformation of Printed Circuit Board during Laser Soldering

This paper presents a numerical simulation approach using the finite element method (FEM) in ANSYS software to overcome the limited accessibility of laser soldering machines which are expensive. The study aims to examine the viability of simulating a laser soldering process using ANSYS steady-state thermal simulation. The simulation aims to produce accurate predictions for temperature distribution, heat flow, and deformation of the material during the process. A Gaussian laser beam equation is used to analyse the interaction between the laser beam and metallic components, particularly on PCB boards. This paper evaluates the properties of a laser beam and the Sn-3.0Ag-0.5Cu (SAC305) lead-free solders which are commonly used in electronic industries. As a result of the thermal analysis, the temperature distribution within the solder spots, as well as the copper as printed circuit board (PCB) can be determined, whereas the mechanical analysis of the materials can be determined by looking at their deformation and stress in the system. The results show that the laser beam effectively contains heat within the solder contacts, reducing the risk of excessive heat transfer. The copper acts as an efficient heat sink, managing thermal energy during the process. However, the solder point experiences substantial deformation and stress, indicating potential limitations in its performance. Nonetheless, the neighbouring components and solder joints exhibit a factor of safety, ensuring the overall safety and reliability of the system.

Excitation of electron plasma wave by self-focused Laguerre–Gaussian laser beams in axially inhomogeneous plasma: effect of orbital angular momentum of photons

Excitation of electron plasma wave by self-focused Laguerre–Gaussian laser beams in axially inhomogeneous plasma: effect of orbital angular momentum of photons

Third harmonic generation of self-focused $${\varvec{q}}$$-Gaussian laser beams in nonlinear media: effect of cubic quintic nonlinearity

Third harmonic generation of self-focused $${\varvec{q}}$$-Gaussian laser beams in nonlinear media: effect of cubic quintic nonlinearity

Combined effect of relativistic and ponderomotive nonlinearities on self-focusing of asymmetric finite Airy–Gaussian laser beams in plasma

Combined effect of relativistic and ponderomotive nonlinearities on self-focusing of asymmetric finite Airy–Gaussian laser beams in plasma

Effects of moderate to weak atmospheric turbulence on the propagation properties of the Whittaker–Gaussian laser beam

Effects of moderate to weak atmospheric turbulence on the propagation properties of the Whittaker–Gaussian laser beam

Ultrashort pulse ablation of printed circuit board materials using a Bessel beam

In times of digitalization, multilayer composite materials became central components in an increasing number of application fields. Thus, there is a need for optimization of the cost-intensive and time-consuming processing of multilayer composites. In this contribution, an ultrashort pulse laser-based method is presented for precise and flexible ablation of a printed circuit board base material. Therefore, an 800 nm Gaussian laser beam was transformed into a Bessel beam by an axicon to get a small spot size and an ablation result with a high aspect ratio. The influence of the average laser power, the number of exposure cycles, and the pulse duration on the geometry as well as the surface quality of ablated structures was investigated and compared to Gaussian beam ablation. Furthermore, it is shown that the results can be transferred to microdrilling processes. With the presented method, it was possible to ablate the copper top layer of the printed circuit boards as well as the FR4 layer below with a precisely adjustable depth.

High-precision positioning of Hall probes for SCU magnetic field measurement

A planar superconducting undulator (SCU) prototype with the magnetic length of 4 m and the magnetic gap of 5 mm is being developed for Shanghai High Repetition rate XFEL and Extreme Light facility (SHINE) to generate vertical linear polarization FELs. The magnetic field measurement device based on Hall probes has been built for the SCU. Three Hall probes mounted on a sledge are used to measure the magnetic field in the undulator gap. The three-dimensional positioning system based on the Gaussian laser beam for the sledge and the Hall probes is presented in detail in this paper.

Variation of structured laser beam pattern and optimization for an alignment reference line creation.

The alignment of particle accelerators demands a dedicated measurement system based on a straight-line reference. This straight line can be provided by a laser beam. The alignment then involves accurately measuring the offset of accelerator components with respect to this light path. In order to be efficient, the laser beam needs to serve as a stable and straight reference for distances of several hundreds of meters. The attainable accuracy depends, among other parameters, on the laser spot size, which should ideally change very little over the distances at which the alignment system needs to operate. Due to the significant divergence of Gaussian laser beams, we propose using a structured laser beam (SLB) for alignment. Its transversal intensity profile is similar to a Bessel beam and consists of an intense inner core (IC) and concentric rings. The divergence of the IC, i.e., the growth of its size with distance, can be limited to 10μrad using a favorable generator configuration. Thus an SLB may be suitable as a straight-line reference for long-distance alignment applications. However, the SLB is distorted if obstructions cover parts of the outermost ring (OR) of the beam within, which should therefore also be small. In this paper, we investigate the relationship between the size of the IC and OR depending on the design parameters of the SLB generator. We use numerical simulations and experiments with different generators over distances up to 50 m to analyze the transversal intensity profile and wavefronts of different SLBs. The results indicate the general suitability of an SLB as a reference line for long-distance alignment but also expose tradeoffs between small IC and small OR. The findings outlined in the paper help to describe the optimal SLB parameters for given conditions.

Simulation of x-ray bremsstrahlung generation under vacuum heating of solid target electrons

An extended Brunel model of hot electron generation in nonrelativistic laser-plasma interactions is considered. The model takes into account the permittivity of the surface plasma and the energy absorbed by electrons accelerated by the electric field components perpendicular and parallel to the target. A model for the generation of x-ray bremsstrahlung in the case of a Gaussian laser beam is presented. It is shown that the influence of electron motion parallel to the plasma surface on the absorbed intensity becomes distinguishable only at relatively low absolute values of the permittivity. Calculations of the dependences of the yield of hard bremsstrahlung x-rays on the angle of incidence of laser radiation and on the energy interval in which the yield of bremsstrahlung is measured are in qualitative agreement with the experimental data, if we assume that the electron concentration in the skin layer is relatively low (approximately 5–7 times the critical concentration).

Self-focusing of Laguerre–Gaussian laser beams in collisionless plasma: paraxial-like approach

Self-focusing of Laguerre–Gaussian laser beams in collisionless plasma: paraxial-like approach

Trajectory planning of deep-cutting laser profiling of superabrasive profile grinding wheels

The low profiling efficiency is the key barrier to the industrial application of laser dressing technology for profile grinding wheels. In this paper, the trajectory planning method of deep-cutting laser profiling was proposed for the first time, the theoretical model of the energy distribution of the Gaussian laser beam on the surface of the profile grinding wheel was established, and the effect of this method on improving the profiling efficiency of superabrasive profile grinding wheel was systematically studied. Through comparative experiments, it was confirmed that the trajectory planning method could effectively improve the profiling efficiency of the V-shaped grinding wheel, and it was found that the smaller the tip angle, the greater the efficiency improvement. The change of grain size will lead to the change of grain removal method, which will affect the profiling efficiency of V-shaped grinding wheel, but it has little influence on the profiling accuracy. The V-tip arc radius of the diamond grinding wheel with a particle size of 20–180 μm after laser profiling could be controlled between 10 and 20 μm, which was difficult to achieve by mechanical or electrical dressing method. The trajectory planning method could also significantly improve the profiling efficiency of convex/concave arc-shaped grinding wheels, and the greater the arc radius or chord-to-diameter ratio of the grinding wheel, the greater the efficiency improvement. Even though convex/concave arc-shaped grinding wheels were the same size, their profiling efficiency and material removal efficiency were quite different. For grinding wheels with different arc radii or chord-to-diameter ratios, different process strategies should be selected during laser profiling to ensure a comprehensive balance between efficiency, accuracy and quality.

Quadruple Gaussian laser beams in thermal quantum plasma: self-focusing, self-trapping and self-phase modulation

Quadruple Gaussian laser beams in thermal quantum plasma: self-focusing, self-trapping and self-phase modulation

Frequency doubling on a metallic surface by Hermite–Cosh–Gaussian laser beam

Frequency doubling on a metallic surface by Hermite–Cosh–Gaussian laser beam

Fabrication of high-aspect-ratio fused silica microstructures with large depths using Bessel-beam femtosecond laser-assisted etching

We propose a facile method for the fabrication of high-aspect-ratio (HAR) fused silica microstructures with large depths using Bessel-beam femtosecond laser direct writing followed by selective chemical etching. First, laser-modified micropatterns with tunable aspect ratios are created in glass using backside Bessel laser irradiation. Then, surface and embedded glass microstructures are formed by selective removal of laser-modified regions through chemical etching. To demonstrate the capability of the proposed method, a vertical surface trench with an aspect ratio of ∼98, a depth of 2.82 mm, and a tapered angle of only ∼0.16°, and a series of periodic column array structures with 3D tunable feature sizes have been processed. Moreover, 3D multi-layer fabrication of embedded microchannels with HAR features has been demonstrated. Compared with conventional Gaussian-beam laser pulses, the proposed Bessel-beam method exhibits superior performance for ultrafast laser manufacturing of HAR glass microstructures with large depths.

Tip and tilt-corrected bit error rate improvement of M-ary pulse position-modulated optical wireless communication in the marine atmosphere

Tip and tilt corrections are applied to the bit error rate of an M-ary pulse position-modulated optical wireless communication system operating in a turbulent marine atmosphere. For the collimated Gaussian laser beam, using the average received power and power scintillation index at the receiver, the reduction in bit error rate is evaluated. Reduction in bit error rate is defined by the metric of bit error rate with tip and tilt correction normalized by the bit error rate without tip and tilt correction. Reduction in bit error rate is found against the changes in average current gain of the avalanche photodiode, data bit rate, and the M value for various structure constant, link length, and wavelength values. Our results show that the application of tip and tilt corrections effectively reduces the bit error rate of the M-ary pulse position-modulated optical wireless communication system in a turbulent marine atmosphere.

Unravelling keyhole instabilities and laser absorption dynamics during laser irradiation of Ti6Al4V: A high-fidelity thermo-fluidic study

A 3D multi-phase thermo-fluidic solver is implemented to investigate the laser-melt pool interaction dynamics and keyhole instabilities during stationary and moving laser irradiation. The physical phenomena such as phase changes, thermocapillary driven flow, multiple reflections of the Gaussian laser beam and beam trapping, vaporization recoil pressure, and heat losses (convective, radiative, and evaporative) have been incorporated in the model. A detailed parametric study has been carried out to investigate the influence of the laser beam spot diameter and the traversal speed on the laser absorption dynamics and melt pool characteristics. For both the stationary and moving laser irradiation, it is found that during the initial transient stage, the melt pool morphology belongs to the conduction melting mode with laser absorption according to the normal incidence condition of the Fresnel equation. Later, depending on the irradiating laser intensity, a melt transition occurs from conduction to the keyhole mode of melting, during which laser absorption rises sharply. The laser absorption and the vapor depression morphology in the keyhole regime show substantial oscillations (periodic and non-periodic) due to the complex hydrodynamics of the recoil pressure, the surface-tension dynamics, and convection-driven flow resulting in the opening and closing of the vapor depression. These oscillations are quantified, and a direct correlation of the laser absorptance with the keyhole depression depth has been observed for stationary laser irradiation. The keyhole closure mechanism and bubble trapping-ejection phenomena have been explored during the solidification stage. The numerically predicted melt pool dimensions match well with the in-house performed experimental measurements and published benchmarking experiments combining integrating sphere radiometry and in-situ X-ray radiography.

Improving the longitudinal and radial forces of optical tweezers: A numerical study

Usually, optical tweezers are based on the focusing a Gaussian laser beam giving rise to a diffraction-limited spot. An alternative has been proposed by several authors which consists to enlighten the trap by a high-order radial Laguerre-Gauss LGp0 beam. However, doing that leaves unchanged the longitudinal stability but improves several times the radial force with increasing the radial mode index p. In this paper, it is demonstrated, for a given power, that introducing a primary spherical aberration (SA) on the path of the incident LGp0 beam allows increasing several times both the longitudinal and transverse trapping effects. The best results are obtained for negative SA.