Ramsay, Jacob Søndergaard3; Dupont, Sune Vestergaard Lund3; Johansen, Mikkel Willum3; Rishøj, Lars Søgaard1; Rottwitt, Karsten1; Moselund, Peter M.1; Keiding, Søren Rud3
1 Department of Photonics Engineering, Technical University of Denmark2 Fiber Optics, Devices and Non-linear Effects, Department of Photonics Engineering, Technical University of Denmark3 Aarhus University
spatial mode dispersion and higher-order mode propagation in ZBLAN step-index fibers
Using femtosecond upconversion we investigate the time and wavelength structure of infrared supercontinuum generation. It is shown that radiation is scattered into higher order spatial modes (HOMs) when generating a supercontinuum using fibers that are not single-moded, such as a step-index ZBLAN fiber. As a consequence of intermodal scattering and the difference in group velocity for the modes, the supercontinuum splits up spatially and temporally. Experimental results indicate that a significant part of the radiation propagates in HOMs. Conventional simulations of super-continuum generation do not include scattering into HOMs, and including this provides an extra degree of freedom for tailoring supercontinuum sources.
Optics Express, 2013, Vol 21, Issue 9, p. 10764-10771