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

Friedrich-schiller-universitaet Jena

Fried-schiller-universitaet Jena

Christian Voigtlaender

Andreas Tuennermann

Stefan Nolte

Jens Limpert

César Jáuregui Misas

Fabian Stutzki

Robert Williams

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

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

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Jena, Germany

Christian Voigtlaender