Ultra-wideband and coherent supercontinuum generation (near and mid-infrared) in dispersion flattened ZnGeP2 photonic crystal fiber

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Transmission window is a major concern in selecting the background material of photonic crystal fiber for supercontinuum generation. In this work, Zinc-Germanium Diphosphide (ZnGeP2) based single material photonic crystal fiber has been proposed with high nonlinearity and low confinement loss for near and mid-infrared supercontinuum generation. As single material is used, hence the concerned difficulties for choosing separate materials for core and cladding is eliminated. Again, the light transmission window of ZnGeP2 is very large (700 nm – 13000 nm). Optical properties like dispersion, numerical aperture, effective area, nonlinearity and confinement loss are analyzed and demonstrated for a wavelength range of 1000 – 5000 nm. COMSOL software is used to design the fiber and finite element method (FEM) is adopted for numerical analysis. The proposed fiber presents low and flattened dispersion in the range of 2250 – 5000 nm, nonlinearity of the order of 104 W–1km−1 and confinement loss of the order of 10–9 dB/m. The fiber is then used for supercontinuum generation in both near and mid-infrared range and an unprecedented bandwidth of 31000 nm has been achieved which may be pragmatic for outstanding medical applications.