Fraunhofer-gesellschaft Zur Foerderung Der Angewandten Forschung E.v.

Friedrich-schiller-universitaet Jena

Friedrich-schiller-universitat Jena

Friedrich-schiller-universitat

César Jáuregui Misas

Jens Limpert

Andreas Tünnermann

Andreas Tuennermann

Fabian Stutzki

Tino Eidam

Fabian Roeser

Christoph Stihler

Jens Ulrich Thomas

Florian Jansen

Stefan Nolte

Christian Voigtlaender

Hans Jurgen Otto

Christian Gaida

Hans-Juergen Otto

Hans-Jürgen Otto

Christian Voigtländer

Fabian Röser

The invention relates to an optical waveguide with two or more light-guiding cores (-) extending continuously along the longitudinal extension of the optical waveguide, parallel to one another and spaced apart from one another, from one end of the optical waveguide to the other, and with a first cladding () enclosing the cores (-). It is an object of the invention to provide a multicore optical waveguide for high-power operation with reduced system complexity compared to the prior art. This object is achieved by the invention in that the cores (-) are arranged relative to one another and are spaced apart from one another in such a way that the propagation modes of the light propagating in the optical waveguide at a working wavelength couple to one another, the length of the optical waveguide being selected such that the light coupled into only a single one of the cores (-) at one end of the optical waveguide first spreads to the other cores (-) during propagation through the optical waveguide and, after passing through the optical waveguide, leaves the optical waveguide again at the other end from a single core () with at least 60%, preferably at least 75%, of the total light power propagating in the optical waveguide. The invention also relates to a laser system with such an optical waveguide as an optical amplifier, and a method for guiding light in an optical waveguide.

Optical waveguide

The invention relates to a method for stably transmitting laser radiation through an optical waveguide (), wherein two or more modes of the laser radiation propagating in the optical waveguide () interfere and form a mode interference pattern in the optical waveguide, as a result of which a thermally induced refractive index grating is produced in the optical waveguide (). It is an object of the invention to demonstrate an effective approach for stabilizing the output signal of the optical waveguide () in a fiber-based laser/amplifier combination at high output powers, i.e. for avoiding mode instability. The invention achieves this object by virtue of the fact that a relative spatial phase shift between the mode interference pattern and the thermally induced refractive index grating is set in the direction of propagation of the laser radiation. In addition, the invention relates to a laser/amplifier combination comprising a laser () and an optical waveguide () in the form of an amplifier fiber, wherein the optical waveguide () amplifies the radiation of the laser () propagating therein. The invention proposes an actuating element (), which produces a predefinable relative spatial phase shift of the mode interference pattern and of the thermally induced refractive index grating in the direction of propagation of the laser radiation.

Avoiding mode instability in an optical amplifier fiber

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 waveguide () as a laser medium or as a gain medium for high-power operation, wherein the optical waveguide () is an optical fiber, the light-guiding core of which, at least in sections, is doped with rare earth ions. It is an object of the invention to provide an optical waveguide as a laser or a gain medium, and a laser/amplifier combination realized therewith, in which the output signal of the laser or gain medium is better stabilized. The invention achieves this object by virtue of the maximum small signal gain of the optical waveguide () being up to 60 dB, preferably up to 50 dB, more preferably up to 40 dB, even more preferably up to 30 dB, on account of the concentration of the rare earth ions and/or the distribution thereof in the light-guiding core. Moreover, the invention relates to the use of such an optical waveguide as an amplifier fiber () in a laser/amplifier combination.

Optical waveguide as amplifier fibre for high-performance operation

The invention relates to an optical waveguide with at least one core region () extending along the longitudinal extent of the optical waveguide, and with a first jacket () which, viewed in the cross section of the optical waveguide, surrounds the core region (). The invention further relates to an optical arrangement with such an optical waveguide, and to a method for producing the optical waveguide. The object of the invention is to make available an optical waveguide for high-performance operation, which is improved in relation to the prior art in terms of mode instability. The invention achieves this object by virtue of the fact that the optical waveguide consists of crystalline material at least in the core region ().

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 method and corresponding devices for reducing mode instability in an optical waveguide (), a light signal becoming unstable in the optical waveguide () beyond an output power threshold and energy being transformed from a basic mode into higher order modes. The invention proposes a reduction in temperature variation () along the optical waveguide () and/or a reduction in changes in the optical waveguide () that are caused by spatial temperature variation as a result of mode interference.

Method and device for reducing mode instability in an optical waveguide

Single-mode propagation in microstructured optical fibers

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.

Growing community of inventors

Jena, Germany

César Jáuregui Misas