Orbital Angular Momentum Mode Propagation and Supercontinuum Generation in a Soft Glass Bragg Fiber

This manuscript presents a ring-core Bragg Fiber (RC-BF) for orbital angular momentum (OAM) modes propagation and supercontinuum generation. The proposed RC-BF is composed of alternating layers of soft glasses SF57 and LLF1 to render high nonlinearity to the fiber. Mode analysis using full-vectorial finite element method resulted in obtaining HE/EH modes to support vector modes as well as orbital angular momentum modes. The optimized fiber supports 22 OAM modes and exhibits a zero-dispersion wavelength (ZDW). The small effective area of Fiber 3 aided in achieving the highest nonlinearity,
$\gamma $
= 91.51
$\text{W}^{-1}$
km
$^{-1}$
. A near-infrared supercontinuum is generated with a 35 dB flatness over a bandwidth of
$\sim $
1087 - 2024 nm in a 20 cm long RC-BF using a chirp-free hyperbolic secant pulse of width 200 fs and peak power of 5 kW.