Highly nonlinear chalcogenide glass micro/nanofiber devices: Design, theory, and octave-spanning spectral generation

In this review we consider the basic elements of tapering chalcogenide optical fibers for the generation of extreme spectral broadening through supercontinuum generation. Creating tapered nanofiber devices in chalcogenide fiber, which has an intrinsic nonlinearity that is two orders of magnitude higher than silica, has resulted in the demonstration of octave-spanning spectra using record low power. We first present a brief theoretical understanding of the tapering process that follows from the basic principle of mass conservation, and a geometric construction tool for the visualization of the shape of tapered fibers. This is followed by a theoretical treatment of dispersion engineering and supercontinuum generation in a chalcogenide nanofiber. In the final section, we cover the experimental implementation of the chalcogenide nanofiber and demonstrate an octave-spanning spectrum created with 150 W of peak power.