Less-dispersive specialty optical fibers with an enhanced operational bandgap for applications in the mid-infrared region

We propose a scheme to enhance the operational photonic bandwidth exploiting the bandgap overlapping of the same order or different orders through judiciously chosen aperiodic geometries of spatial dimension. To implement the scheme, we design a specialty optical fiber with hybrid chirped-cladding. Our designed fiber helps merge the fundamental bandgap with the first higher-order bandgap and thus provides an ultrawide photonic bandwidth of ∼3 μm. The designed fiber structure also provides a much flatter dispersion profile in comparison with conventional periodic cladding fiber carrying the signature of zero dispersion at ∼2.7 μm. This opens up possibilities in the mid-infrared wavelength regime for bandgap-tunable fiber-based devices. The proposed two-solid-material fiber geometry consisted of thermally compatible low-loss chalcogenide glasses, GeAsSe and AsSe as low and high index, respectively. The supported photonic bandwidth of the fiber covers the entire material low-loss window of the chosen glasses. The efficient delivery of short moderate-energy pulses with significantly less distortion in the temporal as well as spectral domain and enhanced spectral broadening of specific high-energy pulses under certain operating conditions are demonstrated through these specialty fibers.