Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V.

Friedrich-schiller-universitaet Jena

Fried-schiller-universitaet Jena

Friedrich-schiller-universtaet Jena

Andreas Tuennermann

Jens Limpert

César Jáuregui Misas

Fabian Roeser

Stefan Nolte

Fabian Stutzki

Tino Eidam

Enrico Seise

César Jauregui Misas

Damian Schimpf

Dirk Nodop

Christian Voigtlaender

Gerhard Kalkowski

Ernst-Bernhard Kley

Ramona Eberhardt

Arno Klenke

Christoph Stihler

Alexander Steinmetz

Kevin Fuechsel

Robert Williams

Christoph Jocher

Hans-Juergen Otto

A method of propagating a laser signal through an optical waveguide and a waveguide laser system provide a novel way of stabilizing the beam emitted by a fiber laser system above the mode instability threshold wherein the beat length of two or more interfering transverse modes of the laser signal in the optical waveguide is modulated in time.

Active stabilization of mode instabilities in optical waveguides

The invention relates to an optical amplifier arrangement for amplifying ultra-short pulsed laser radiation comprising a mode-locked laser () and two or more optical amplifiers () arranged downstream of the laser () in the propagation direction of the laser radiation. Optical amplifier arrangements of this type are known in the prior art. Here the intention is to present an alternative to the known amplifier arrangements. The invention proposes arranging between the laser () and the optical amplifiers () at least one splitting element () which splits the pulsed laser radiation between a plurality of amplifier channels (), wherein each amplifier channel () has at least one optical amplifier (), and wherein at least one common combination element () is disposed downstream of the amplifier channels () and coherently superimposes the pulsed laser radiation amplified in the amplifier channels ().

Optical amplifier arrangement

The invention relates to an apparatus for generating azimuthally or radially polarized radiation by means of an optical waveguide (), wherein the optical waveguide () has a structure which is suitable for conducting azimuthally or radially polarized modes (). The invention proposes that the azimuthally or radially polarized modes () in the optical waveguide () have different effective refractive indices and, within the optical waveguide (), a narrow-band grating () is arranged, in particular a fiber Bragg grating () which is designed such that the spectral distance between two azimuthally or radially polarized resonant modes () is equal to or greater than the associated spectral bandwidth.

Generation of azimuthally or radially polarized radiation in optical waveguides

The invention relates to an optical fiber as an optical waveguide for the single-mode operation. The present invention proposes a fiber having a microstructure, by which the propagation of modes of a higher order are selectively suppressed in the optical waveguide. At the same time, the propagation of transversal modes of a higher order is dampened more strongly than the propagation of the fundamental modes of the optical waveguide.

Single mode propagation in microstructured optical fibers

The invention relates to a mode filter for reducing higher-order modes, with an optical fiber (), which has a core () and a cladding () surrounding the latter, wherein the cladding () and core () have refractive indices that differ from one another. In order to develop an alternative to the prior art, the mode filter according to the invention is designed in such a manner that the fiber () has, in a transition region () between core () and cladding (), at least one local refractive index modification region () which is arranged in the radially outer region of the core () and extends into the region of the cladding ().

Mode filter with refractive index modification

Single-mode propagation in microstructured optical fibers

The invention relates to a double-sheath fiber having a core region () and a sheath region, the sheath region having an inner region () and an outer region (), which comprises a refractive index that is lower with respect to that of the inner region () and the core region (), wherein the outer region () surrounds the inner region (). The invention proposes an internal structure () of the inner region () which effects a spatial overlap of modes of higher order with the core region (), which is lower than the spatial overlap of a fundamental mode with the core region ().

Structured double-sheath fiber

The invention relates to an apparatus for generation of electromagnetic radiation, having a pump light source that emits an excitation radiation at a first wavelength, and having an optical waveguide that generates frequency-converted radiation at a second and a third wavelength, by means of degenerate wave mixing, from the excitation radiation of the pump light source.

Efficient frequency conversion

The invention relates to a laser device () for amplifying and/or transporting electromagnetic radiation, comprising a radiation source () for generating the electromagnetic radiation and an amplifier () for amplifying or a medium for transporting the generated electromagnetic radiation. In order to make available a device () for amplifying or transporting electromagnetic radiation that provides a very easy to implement possibility for reducing the influence of non-linear effects, the electromagnetic radiation propagating in the amplifier () or medium is largely non-linearly polarized.

Device for amplifying and/or transporting electromagnetic radiation

The invention relates to a laser system with a passively Q-switched laser, a spectrally widening element, and a compression element. Laser systems of this kind are utilized for generating ultra-short laser pulses. Systems, mode-coupled solid-state lasers known from prior art allow for generating laser pulses in the sub-10 ps range only with complicated and alignment-sensitive free-beam arrangements. Therefore, it is the object of the present invention to create a laser system that generates pulse durations of less than 10 ps and which is simple and compact to produce at the same time. In order to achieve this object, the present invention proposes that the passively Q-switched laseris provided with a longitudinally monomode output radiation which is spectrally widened by means of the spectrally widening elementby self-phase modulation and is temporally compressed by the compression element

Laser system with nonlinear compression

The invention relates to a transverse mode filter in an optical waveguide (). The aim of the invention is to produce a transverse mode filter that permits a monolithic construction of a laser in a multi-mode waveguide. To achieve this, according to the invention the filter comprises a Fabry-Perot cavity integrated into the optical waveguide () and comprising two reflective elements () situated at a distance from one another. In addition, the waveguide () is modified in the region of the Fabry-Perot cavity and/or in the region of the reflective elements () in relation to the remaining regions of the waveguide with respect to the effective refractive index of at least one mode of the waveguide.

Transverse mode filter for waveguides

The present invention relates to a method for laser-assisted bonding of substrates, in which these are connected together firstly frictionally by pressing together and subsequently strengthening of the connection between the substrates is effected by activation in regions which is induced by laser irradiation. The invention likewise relates to substrates produced accordingly.

Method for laser-assisted bonding, substrates bonded in this manner and use thereof

The present invention relates to a device () and to a method for amplifying light impulses (). The device comprises a stretcher () stretching the light impulses over time, at least one amplifier () amplifying the stretched light impulses, and a compressor () compressing the stretched and amplified light impulses, wherein the amplifier () applies a non-linear phase generated by self-phase modulation to the stretched light impulses. In order to provide a device and a method for amplifying light impulses, by means of which light impulses having higher light impulse quality and light impulse peak power can be generated, the invention proposes that means for spectrally shaping the light impulses are disposed ahead of the amplifier () in the beam path, wherein the means for spectrally shaping the light impulses bring about a spectral trimming of the light impulses.

Device for amplifying light impulses

The present invention relates to a device () for amplifying light pulses (), the device comprised of a stretcher () which temporally stretches the light pulses (), and comprised of at least one amplifier () which amplifies the stretched light pulses (), and comprised of a compressor () which recompresses the stretched and amplified light pulses (), the stretcher () and the compressor () being dispersive elements with essentially oppositely identical dispersion. To provide a device () for amplifying light pulses () which is of a compact setup and which can be flexibly applied, the present invention proposes that the dispersion of the amplifier (), the dispersion of further optical elements of the device () and/or a mismatch of dispersion of the stretcher () and compressor () are at least partly compensated by self-phase modulation of the light pulses () and/or by at least one additional element () of variable dispersion.

Device for amplifying light pulses

It is an object of the present invention to provide a compact and low-cost system for generating ultra short high energy laser light pulses that does not use the known CPA scheme. The proposed approach is based on spectral filtering of laser light pulses of a mode locked laser source. The used mode locked laser source can be of any kind as long as its filtered residual pulse bandwidth supports pulse durations longer than 20 ps and up to 1 ns. After filtering the laser light pulses are directly amplified in an amplification element consisting of one or more amplification stages. At the same time or just after amplification the light pulses are spectrally broadened through a spectral broadening element, for example a fiber of suitably chosen core diameter and length to achieve a spectral bandwidth that is wide enough to support sub 10 ps pulses. Finally, the spectrally broadened laser light pulses are compressed by a compact dispersive element consisting of one or more Bragg gratings or a grating pair.

Growing community of inventors

Weimar, Germany

Andreas Tuennermann