Design of all-normal dispersion with Ge_11.5As₂₄Se_64.5/Ge₂₀Sb₁₅Se₆₅ chalcogenide PCF pumped at 1300 nm for supercontinuum generation

Supercontinuum spectrum generation is a process in which laser beam in femtoseconds and high power (kilowatts) is converted into a broad-spectrum beam of light after passing through a specific environment. Of course, achieving this range comes with many limitations. In this paper, photonic crystal fibers are used as a substrate for input pulse due to the ability to control dispersion and loss, and creating single-mode operating conditions. One of the main factors for the formation of supercontinuum spectra of injection pulses is maintaining the nonlinear performance of this type of fiber by controlling the effective mode area and also using chalcogenides (nonlinear coefficients about 100 times higher than silica) in their structure. In the proposed structure, a photonic crystal fiber with silica base element and air cavities with hexagonal structure with the center of Ge_11.5As₂₄Se_64.5 chalcogenide element have been used to provide the nonlinear property of the structure. Also, in this structure, a ring of Ge₂₀Sb₁₅Se₆₅ chalcogenide elements has been used to reduce the effective mode region and create a flat dispersion curve at a wavelength of 1300 nm (second telecommunication window). The input pulse power is 10 kW and its width is 50 femtoseconds, which has caused the range of the supercontinuum from 800 to 1900 nm. This structure can be used to provide the required wavelengths as a carrier in a wavelength division multiplexing.