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Our researchers have been able to generate broadband laser light in the mid-infrared range by means of liquid-filled optical fibers. With these fibers, they also provided experimental evidence for a new dynamics of solitons - timely and spectrally stable light waves - due to the special properties of the liquid core.
The scientists produce a very broad spectrum of light in the near to middle infrared range (1.1 to 2.7 μm), which is not visible to the human eye, from an ultrafast laser pulse, which they couple into the fiber. Due to the special properties of the liquid fiber core, the light pulse breaks into a plurality of light waves of different wavelength, the solitons. They form the extremely broadband laser light, which is indispensable as a supercontinuum light source for applications in medical imaging, measurement technology and spectroscopy.

Carbon disulfide shows non-linear optical effects and high transmission

The coupled light pulse breaks in the optical fiber only in solitons when it interacts non-linearly with matter. In the case of the liquid core fibers, this means that the optical density of the liquid in the core changes massive with the intensity of the irradiated light. Only a few materials show non-linear optical effects and at the same time have good light transmission in the infrared range. Mario Chemnitz, IAP alumnus, and now member of the Leibniz-IPHT staff, explains the unusual effect: "Carbon disulfide, a liquid chemical compound that breaks the light very strongly, is located in the fiber core. If we now irradiate polarized laser light, the carbon disulfide molecules are directed in the electromagnetic field of the light. This molecular orientation and the light propagation in the fiber depends on the intensity of the laser light. "

IPHT Jena Solitons
Figure: IPHT Jena. Schematic illustration of an ultrashort light pulse, which breaks in in solitons the fiber.

Optical memory effect

A special feature of carbon disulfide is that the molecules align themselves with a certain time delay. If the irradiated laser light pulse is much shorter than the time required for the molecules to orientate in the optical field, the scientists observe a particular, delayed dynamics of the resulting solitons. It was already predicted in 2010, but now the experimental proof and an exact theoretical description of the processes has succeeded. The phenomenon can be described as an optical "memory effect" of the liquid. This unique property of the liquid core fibers ensures that the spectral bandwidth of the light generated in the fibers is less fluctuating. They thus form a more stable alternative to hitherto known broadband light sources which are based on optical fibers of special glasses.
The results of the work were published by a team of researchers from the Leibniz Institute for Photonic Technologies (Leibniz-IPHT), IAP, Fraunhofer-IOF and the Helmholtz Institute in the renowned "Nature Communications ".

Original publication:

Mario Chemnitz, Martin Gebhardt, Christian Gaida, Fabian Stutzki, Jens Kobelke, Jens Limpert, Andreas Tünnermann und Markus A. Schmidt: "Hybrid soliton dynamics in liquid-core fibres", Nature Communications, DOI: 10.1038/s41467-017-00033-5

original article in german >>> here

News from: 17.08.2017 14:14
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