An optical fiber, used in a laser device, propagates light having a wavelength of 1060 nm through a core in at least an LP01 mode and an LP11 mode. A difference between a propagation constant of light in the LP01 mode and a propagation constant of light in the LP11 mode is 1850 rad/m or more and 4000 rad/m or less.

Optical fiber and laser device

FIELD: metallurgy.SUBSTANCE: invention relates to a method of preliminary selection of parameters of welding of metals/alloys irrespective of spectral properties of shielding gas, to method of creation of welding seam of metal/alloy in workpiece irrespective of spectrum of protective gas and narrow-band fibre laser. Electron transition of metal/alloy vapour is determined by analysing the radiation spectrum of the metal/alloy welding process using a broadband power source and selection of laser wavelength and line width outside electron/metal alloy electronic transition spectrum. Laser comprises a fibre Bragg grating to obtain output radiation in a given narrow spectral band corresponding to the width of the spectral band, which differs from the electronic transition spectrum of metal/alloy vapour, active fibre capable of suppressing non-linearities, and laser diodes made with possibility of active fibre pumping so that it can generate laser radiation with narrow spectral band.EFFECT: technical result of invention consists in fact that pre-selected width of spectral bands, which bypass spectrum of electronic transition of metal/alloy vapour, enables to obtain welding seam practically without deposits, that is unpainted seam.13 cl, 12 dwg

Preliminary analysis and concomitant laser welding methods and fibre lasers with application of preselected width of spectral bands to bypass electronic metal/alloy vapour transition spectrum

The invention relates to a fiber active device based on a europium ion doped fluorescence fiber Feature fluorescence with a wavelength of 618nm can be generated in D0 F2 energy-order transition of trivalent europium ions of the device based on the europium ion doped fiber, and due to an effect of a unique coordination field of fused silica, hypersensitive transition of the trivalent europium ions is enabled to have a quite wide wavelength scope. A fiber laser and a fiber amplifier which are made by the europium ion doped fiber both have the following features: the center wavelength is 618nm, and the wavelength tuning range reaches 13nm. At present, the wavelengths of a doped active fiber laser and an active fiber amplifier are mainly at an infrared or near infrared waveband, reports about a fiber laser and a fiber amplifier at a visible light waveband are not seen yet, and therefore, it can be seen that the fiber laser and the fiber amplifier at the visible light waveband are uniquely innovative.

Fiber active device based on europium ion doped fluorescence fiber

The present invention benefits from the determination that pre-selected spectral bandwidths that avoid the spectrum of an electronic transition of a metal/alloy vapor allow for welds substantially free from detritus that may discolor the weld. Accordingly, the present invention provides analytical methods, welding methods and fiber lasers configured to provide high quality metal/alloy welds.

Pre-Welding Analysis and Associated Laser Welding Methods and Fiber Lasers Utilizing Pre-selected Spectral Bandwidths that Avoid the Spectrum of an Electronic Transition of a Metal/Alloy Vapor

The invention discloses an efficient retroreflector based on a non-uniform Fabry resonant cavity array. The reflector is mainly composed of a plurality of arch-shaped metal sheets, the distances between every two adjacent arch-shaped metal sheets are equal, each arch-shaped metal sheet is formed by splicing two short metal sheets with the same length and a long metal sheet, and the two short metalsheets with the same length are connected to the two ends of the long metal sheet respectively to form an arch shape. The end parts of the short metal sheets at one ends of the arched metal sheets are flush with one another to form a port I of the reflector; and the end parts of the short metal sheets at the other ends of the arched metal sheets are flush with one another to form a port II of thereflector. The structure is simple, the thickness is small, the weight is light, the structure is perfectly matched with free space, and the structure can be widely applied to radar target modeling,sensing and other fields.

Efficient retroreflector based on non-uniform Fabry resonant cavity array

A multimode ("MM") fiber oscillator is configured with MM active fiber doped with, light emitters, a pair of MM passive fibers spliced to respective opposite ends of the MM active fiber, and a plurality of MM fiber Bragg gratings ("FBG") written in respective cores of the MM passive fibers to provide a resonant cavity. The passive and active fibers are configured with respective cores which are dimensioned with respective diameters matching one another and substantially identical numerical apertures.

Multimode fabry-perot fiber laser

A method of inducing light losses at a parasitic wavelength in a fiber laser system includes providing a wavelength discriminator (WD) spaced from and between feeding and process fibers or from the end output of the feeding fiber so as to induce losses of light at parasitic wavelength. The device implementing the disclosed method is configured with a laser source, the delivery fiber and WD spaced at a distance between the surface to be treated and the end of the delivery fiber, wherein the WD receives the parasitic light over free space and is configured as a dichroic filter inducing losses to the light at the parasitic wavelength.

Andrey Mashkin

Papers

Multimode fabry-perot fiber laser

Fiber laser system with mechanism for inducing parasitic light losses