Design of hexagonal photonic crystal fiber with Ge₁₀As₂₂Se₆₈ chalcogenide core and As₂S₃ cladding for mid-infrared supercontinuum generation

In this paper, we propose a hexagonal photonic crystal fiber (PCF) suitable for broadened mid-infrared supercontinuum generation. The designed PCF has five air-hole rings with three different air holes, arranged in a triangle pattern. The central air hole is filled with \(Ge_{10}As_{22}Se_{68}\) and the inner wall of the air hole is coated with \(As_{2}S_{3}\). In the mid-infrared wavelength range of 3400 nm to 4500 nm, the supercontinuum bandwidth increases with the increase of the pump wavelength, peak power, and pulse width. When the pump light source with a peak power of 5 kW and the input pulse width is 200 fs, a 10 mm fiber can produce an extremely wide supercontinuum spectrum spanning 6000 nm. In addition, optical parameters including dispersion, confinement loss, effective mode area, and nonlinear coefficients are numerically investigated by the finite element method. The results show that at a wavelength of 4000 nm, the second order dispersion of the fiber is \(8.81\times 10^{-27} \textrm{s}^{2}\textrm{m}^{-1}\) and the nonlinear coefficient is \(972.5 \textrm{W}^{-1}\textrm{km}^{-1}\). The designed photonic crystal fiber is stable, dispersion flat, and can meet the application requirements of obtaining broad supercontinuum spectrum.