1.6-Octave Coherent OAM Supercontinuum Generation in As₂S₃ Photonic Crystal Fiber

Abstract

We design and simulate an all-normal dispersion arsenic trisulfide (As <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) photonic crystal fiber (PCF) with high nonlinearity to enable a flat and coherent orbital angular momentum (OAM) supercontinuum (SC) generation. The photonic crystal fiber features a near-zero and flat negative dispersion with variation between -96.5 and -36.5 ps/(nm·km) over a 940-nm wavelength range from 1740 to 2680 nm. A 1946-nm supercontinuum forms from 959 to 2905 nm at -20 dB level which covers a 1.6-octave bandwidth, by launching a 100-fs 5-kW chirp-free hyperbolic secant pulse with wavelength at 2000 nm into a 1.0-cm designed fiber. The generated supercontinuum of the other two vortex modes (TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> ) can cover more than two octaves by optimizing the proposed fiber structures. The coherence of the generated supercontinuum of the three modes all shows nearly perfect property over the whole bandwidth. In general, we found that the designed ring-core As <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PCF with all-normal dispersion could be used for broadband coherent supercontinuum generation of various vortex modes.