Coherence evolution of multi-pulse pumped super-continuum in multicomponent GeSe₂-As₂Se₃-PbSe chalcogenide photonic crystal fiber with four zero-dispersion wavelengths

The flattened dispersion profile with multiple zero-dispersion wavelengths (ZDWs) over an ultra-wide wavelength range can be used to generate rich nonlinear effects, and one of the advantages of its use is the generation of super-continuum (SC). In this work, we proposed a new, to our knowledge, solid hybrid PCF of GeSe 2 -As 2 Se 3 -PbSe chalcogenide to achieve ultra-flat and low dispersion with four ZDWs. By tuning the structural parameters of the fiber, an ultra-flat dispersion between −2.1 and 0.6 ps/nm/km (a variation of 0.75 ps/nm/km) is achieved over a bandwidth of 5077 nm. The presence of four ZDWs results in an ultra-flat and wider bandwidth dispersion profile in comparison with PCFs with one, two, or three ZDWs. An ultra-broadband coherent SC spectrum with a bandwidth of 8107 nm, extending from 2827 to 10934 nm wavelength at a level of 45.6 dB, was generated by injecting an input laser pulse with a pump wavelength of 5.3 µm, a pulse width of 150 fs, and a peak power of 4.5 kW into a 20 cm long fiber in the anomalous dispersion region. Meanwhile, high coherence of the SC spectrum from 3253 to 10850 nm (bandwidth of 7597 nm) wavelength at a level of 19.3 dB can be generated in the normal dispersion region with the same pump power at a pump wavelength of 8.0 µm. The results show that the proposed hybrid PCF has great potential for nonlinear applications in the mid-infrared range.