Abstract In this study, the design and characterization of a photonic crystal fiber (PCF) as a light source for a mid-infrared supercontinuum generation (SCG) is presented. This PCF is based on a highly nonlinear chalcogenide $${\text{As}}_{40}{\text{Se}}_{60}$$ As 40 Se 60 background material with a hexagonal structure arrangement of air-holes rings. The PCF parameters such as the chromatic dispersion (D), the effective refractive index ( $${n}_{eff}$$ n eff ) and the nonlinear coefficient (γ) have been investigated. We study the stimulated SCG in two types of dispersion regimes: anomalous and all-normal dispersion (ANDi). We initiate the study by sending a 28.4 fs wide optical pulse with a peak power of 10 kW and a central wavelength of 2.8 µm through a 2 cm long PCF. In the anomalous dispersion, we demonstrate the generation of coherent and broadband SCG spectrum spanning the wavelength region from 1.6 to 7.8 µm. While, in the ANDi regime we demonstrate the generation of a broad, ultra-flat-top and highly coherent SCG spectrum extending from 2 to 4 µm at 6 dB spectral flatness. Thus, we achieve ultra-flat SCG spectrum source with a bandwidth as wide as 2400 nm within only 2 cm propagation length of the proposed PCF. This spectrum range is very suitable for variety of applications in mid-infrared region such as optical metrology, frequency comb generation, and optical coherence tomography (OCT). Results further demonstrate that with an applied pump power of 15 kW through the ANDi regime, a flat spectral bandwidth of 380 nm (wavelengths ranging from 1260 to 1640 nm) at just 3 dB spectral flatness is achieved. This band covers the five-telecommunication optical bands O-, E-, S-, C- and L-bands that comply with ITU-T-compliant wavelengths for wavelength division multiplexing (WDM) applications like coarse WDM (CWDM) and dense WDM (DWDM).

In this study, the effects of β-Ga2O3 film thickness on morphological, topological, compositional, structural, optical, and optoelectronic properties were examined. The films were deposited onto sapphire and quartz substrates using electron beam evaporation. The surface roughness of the films was analyzed using atomic force microscopy, showing an increase from 2.70 nm to 5.03 nm as the film thickness increased. The grain size transitioned from sparse, tiny grains to a more uniform distribution of slightly larger grains, as revealed by field emission scanning electron microscopy. The presence of gallium and oxygen atoms was confirmed through energy-dispersive X-ray spectroscopy. The films showed β-Ga2O3 polycrystalline structures as confirmed by X-ray diffraction analysis. The inter-planar spacing and crystallite size increased from 6.67 to 10.74 nm as film thickness increased. In contrast, the energy band gap decreased from 5.12 eV to 4.87 eV. The optical density, skin depth, optical sheet resistance, and thermal emissivity were in the order of 0–3, 102 cm, 10–7 Ωm2, and 10–12, respectively. The study also revealed that the optoelectronic parameters such as optical density, refractive index, packing density, dispersive energy, single oscillator energy, charge carrier concentration, plasma frequency, relaxation time, optical conductivity and resistivity increased with the thickness of the films. In contrast, other parameters such as skin depth, absorption coefficient, extinction coefficient, band gap energy, porosity, lattice dielectric constant, optical sheet resistance, and thermal emissivity decreased as the film thickness increased.