Vladimir P. Pashinin

Fused silica fibers for the delivery of high-power UV radiation

A set of all silica step index fibers was produced using PCVD and PMCVD methods. The influence of the fiber production technology and chemical composition of silica core on the transmission characteristics of fibers in the UV range, as well as on the processes of color centers formation, was studied. The experiments were carried out for the excimer laser wavelengths 308 nm (XeCl) and 248 nm (KrF).

Formation of nonstable color centers in fused silica fibers induced by high-power XeCl laser radiation

The transmission properties of fused silica fibers irradiated by high power high repetition rate XeC1 laser have been investigated. Laser-induced additional losses of radiation were measured as a function of intensity and of repetition rate.

Mechanism of UV laser-induced absorption in fused silica fibers

Abstract An alteration of absorption spectra of fused silica fibers under delivery of high-power (ultraviolet) UV laser radiation (4th harmonic of the Nd:YAG laser, wavelength 266 nm) was studied in comparison with their photoluminescent properties. Tested fibers were produced by various technologies based on PMCVD methods. The nature of defects responsible for UV absorption in fibers and the mechanisms of their photogeneration are discussed.

Silica Fibers with Enhanced UV Performance

In developing a better understanding of the requirements on optical fibers to make them more useful for medical and other applications where UV light/lasers are the preferred source, previous papers have dealt with all silica optical fibers. Here we describe the UV transmission of all the available fiber types; illustrating, for commercially available fibers, the effects of fiber type, core diameter, cladding thickness, and core OH level on this transmission. We also describe our first efforts to fabricate a new, modified hard plastic clad silica fiber with enhanced UV performance. Finally some of the remaining problems and concerns are identified and reviewed.

Mechanisms of UV-laser-induced absorption in fused silica fibers

Alteration of absorption spectra of fused silica fibers under delivery of high power UV laser radiation (4th harmonic of Nd:YAG laser, wavelength 266 nm) was studied in comparison with their photoluminescence properties. Tested fibers were produced by various technologies based on PMCVD methods. The nature of defects responsible for UV absorption in fibers and mechanisms of their photogeneration are discussed

New alternative for laser lithotropsy-long pulse passively q-switched solid-state laser with fiber-based resonator

This paper presents an overview of the important processes which are responsible for stone fragmentation. The efficiency of these processes in dependence of wavelength and laser pulse duration is discussed. Beside shockwaves and cavitation phenomena the role of a compressional shock acting on the stone and the plasma confinement is emphasized. As a conclusion the concept of a passively Q-switched solid state laser with a fiber-based resonator which prolongs the pulse duration is presented.

Laser nanoablation of diamond surface at high pulse repetition rates

The chemical etching of the surface of a natural diamond single crystal irradiated by subpicosecond laser pulses with a high repetition rate in air is experimentally investigated. The irradiation has been performed by the second-harmonic radiation of a disk Yb : YAG laser. Dependences of the diamond surface etch rate on the laser energy density and pulse repetition rate are obtained.

Active mode locking of picosecond Ti{sup 3+}:Al{sub 2}O{sub 3} and Cr{sup 4+}:Mg{sub 2}SiO{sub 4} lasers pumped by 0.5 - 5-{mu}s laser pulses

Picosecond pulses are generated in actively mode-locked Ti:sapphire and Cr:forsterite lasers pumped by 0.5 — 5-μs pulses from a Nd:YAG laser.

Comparative study of gelatin ablation by free-running and Q-switch modes of Er:YAG laser

To optimize the laser ablation of soft wet tissues by Er:YAG laser radiation at 2.94 micrometers the dynamics of ablation is investigated by high-speed photography techniques. Gelatin as model material is used.