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Unique method to determine the differential mode delay of specialty multimode fibers

: Wittig, M.; Baselt, T.; Nelsen, B.; Hartmann, P.


Kalli, K. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Micro-structured and Specialty Optical Fibres V : 26-27 April 2017, Prague, Czech Republic
Bellingham, WA: SPIE, 2017 (Proceedings of SPIE 10232)
ISBN: 978-1-5106-0965-5
ISBN: 978-1-5106-0966-2
Paper 102320L, 6 pp.
Conference "Micro-Structured and Specialty Optical Fibres" <5, 2017, Prague>
Conference Paper
Fraunhofer IWS ()

We developed an experimental setup for the determination of the differential mode delay (DMD) in fibers. This unique method of measurement is the basis for the characterization of specialty fibers including properties such as the chromatic dispersion, the fiber geometry and the DMD. These fibers have their application in the nearinfrared and mid-infrared regime. Examples of uses of such fibers are supercontinuum light sources and high power lasers. Different modifications of these multimode fibers are applicable in extreme environments or for standard beam delivery over long distances. The exact knowledge of parameters such as the DMD is necessary to generate light sources with ether high energy, high intensity or high power or to analyze transmitted information when the fiber is used in a configuration for communication. For the most precise measurement of DMD, we investigated a new type of method. It is capable of measuring the modal dispersion in two different ways. The first way is the standard transversal measurement, where the launching condition is altered by moving the radial position of the injected pulse while maintaining a zero-angle launching condition. The second way involves changing the launching angle into the fiber. This is done to get the most precise value for the DMD. Also, using a supercontinuum light source for the injection pulse, it is possible to vary the wavelength to be able to measure near the zero dispersion wavelength in order to investigate the effects of the chromatic dispersion.