Common Laser Systems Research Articles

Gold nanostructures deposition by laser ablation in air using nano- and femtosecond laser pulses

This work demonstrates nanostructures deposition using nanosecond and femtosecond laser ablation in air. The laser parameters correspond the most common laser systems—Nd:YAG, operated at 1064 and 532 nm and Ti:Sapphire at 800 nm. In the case of nanosecond pulses, the deposited material forms a complex structure that is composed by microsized droplets and nanoparticles with a narrow size distribution. The structure composed of nanoparticles expresses different features for the IR and visible laser radiation. Laser ablation at 532 nm is found to be more efficient as it leads to formation of complex 3D highly porous nanostructures. Femtosecond laser ablation in air results in deposition of nanoparticle aggregates with a broad nanoparticle size distribution. The performed analyses on the structure and chemical composition of the deposited material indicate that no oxide and nitride compounds of gold are formed. The presented results demonstrate the basic characteristics of a method for direct deposition of nanostructured material in open air that can find application in fabrication of sensor devices, in catalysis and plasmonics.

Determining ways of improving the tribological properties of the silicon carbide ceramic using a pulse-periodic laser treatment

Laser surface microstructuring is applied to improve the tribological properties of materials. To increase potential practical applications, the expansion of the laser microstructuring functionalities through the use of more common laser systems with pulse durations in the millisecond range may show promise. For the first time it was shown that the tribological properties of the surface of the silicon carbide ceramic can be improved using a pulse-periodic laser treatment with millisecond pulses. Morphological changes of the surface under treatment after the exposure to pulse-periodic laser light were assessed. It was found that the pulse-periodic laser treatment with 0.5-ms pulses of energy 1.1 J led to the smoothing of recesses in the polished surface of the silicon carbide ceramic. Higher-energy laser treatment led to the formation of cracks on the material surface. The study of tribological properties of the resulting structures showed that following the laser treatment the mean value of the friction coefficient decreased by 15 %.

Modification of the surface of silicon carbide parts by laser treatment for improving their tribological properties

Laser microstructuring of the surface can be used for improving tribological properties of materials. Thistrend suggests a laser treatment to create on the materials surface microstructures with spatial selectivity ofphysical-mechanical properties, such as microhardness, friction factor, etc. The microstructuring of the externalsurface of gas-dynamic compactions is perspective. To increase the capacity of the practical use of it is expedientto enhanced functionality through the use of laser microstructuring of the more common laser systems with pulsedurations in the millisecond range. A method of surfaces modification of silicon carbide details by lasertreatment for improving their tribological properties has been developed. A material structure in the heat-affectedzone after laser microstructuring has been studied. Evaluated the morphological changes of the treated surfaceafter a repetitively pulsed laser exposure. It was established that the pulse-periodic laser exposure leads to theformation on the polished surface of the silicon carbide parts recesses are round to oval. Along with theformation of acyclic microrelief occurs modifying surface structure details. Under laser exposure on the surfaceof the ceramic material is a decomposition of silicon carbide and graphite to form a solid solution of carbon insilicon. Supposed to carry out the study of the tribological properties of the resulting structures.

Generation of multi-color carrier-envelope phase locked pulse with continuous color tunability

Several methods exist to lock carrier envelope phase (CEP), which is generally not locked in common laser systems. Our previous work succeeded passive lock of CEP by using a technique of non-collinear optical parametric amplifier. In the present work, we have proposed and demonstrated two schemes to generate multi-color CEP-locked beams using the non-collinear optical parametric amplifier. In the first scheme, spatial filter in the spatially dispersed seed light was used to generate three-color CEP-locked pulse demonstrating its arbitral color tunability. In the second scheme, parabolic chirp was introduced on the seed pulse to generate two color CEP-locked pulses with continuous color tunability.

Comparison of Atom Interferometers and Light Interferometers as Space-Based Gravitational Wave Detectors

We consider a class of proposed gravitational-wave detectors based on multiple atomic interferometers separated by large baselines and referenced by common laser systems. We compute the sensitivity limits of these detectors due to intrinsic phase noise of the light sources, noninertial motion of the light sources, and atomic shot noise and compare them to sensitivity limits for traditional light interferometers. We find that atom interferometers and light interferometers are limited in a nearly identical way by intrinsic phase noise and that both require similar mitigation strategies (e.g., multiple-arm instruments) to reach interesting sensitivities. The sensitivity limit from motion of the light sources is slightly different and, in principle, favors the atom interferometers in the low-frequency limit, although the limit in both cases is severe.

System performance evaluation of refractive surgical lasers: a mathematical approach

A study was conducted for the purpose of improving the designs of the next generation of refractive surgical laser systems. Two common refractive laser systems, variable-spot scanning (type A) and small-spot scanning (type B), are discussed by identifying sources of error that could adversely affect the capability of these lasers to accurately produce complex, customized wavefront guided ablations. A mathematical model was used to construct a laser simulator that models the two common laser systems in terms of the root-mean-square error. Error sources from ablation profile fitting, ablation registration, eye tracking, and the laser delivery system are compared, and the relative contribution of each to the overall system error is analyzed. This system-level analysis can be helpful to the improvement of both laser systems.

Photoablation of bone by excimer laser radiation

Background and Objectives The aim of the present study was to compare the usefulness of mechanical osteotomy tools and common laser systems with the ultraviolet (UV) laser in the field of the central nervous system and its bony capsule. Study Design/Materials and Methods The cranial bones of 42 living rats were treated with UV laser radiation with wavelengths of 193 nm and 248 nm. The morphology and physical effects were evaluated by means of optical and scanning electron microscopy. Results This study shows the special characteristics of excimer versus infrared lasers or mechanical tools, such as high precision, no thermic damage, little depth effect, and no delay of healing processes. Conclusion The excimer laser is an interesting instrument for microsurgery of bones in orthopaedics, neurosurgery, and otolaryngology. Lasers Surg. Med. 25:153–158, 1999. © 1999 Wiley-Liss, Inc.

Efficient temporal compression of coherent nanosecond pulses in a compact SBS generator-amplifier setup

A pulse compressor based on stimulated Brillouin scattering (SBS) in liquids is experimentally and theoretically investigated. It allows for the compression of Fourier-transform limited nanosecond pulses of several hundreds of millijoules of energy with both high conversion efficiency and a high temporal compression factor. The two-cell generator-amplifier arrangement is of a compact design not requiring external attenuation of the generator cell input energy. Pulses from an injection-seeded, frequency-doubled Nd:YAG laser of 300-mJ energy were compressed by a factor variable between 6 and 21 at up to 75% reflectivity. Deviation from unity SBS reflectivity is predominantly determined by optical component losses. The generation of 270-ps pulses with high beam quality was achieved in liquid methanol. These powerful pulses of variable duration are difficult to produce with common laser systems and are highly suited for the generation of high-harmonics in gases.