This work introduces a newly designed As2S3-based photonic crystal fiber structure optimized for generating broadband mid-infrared supercontinuum under low peak power excitation. The hexagonal-core configuration enhances both dispersion and nonlinear characteristics by adjusting structural parameters. Two optimized models, F1 (Lambda = 1.0 & micro;m, f = 0.35) and F2 (Lambda = 2.0 & micro;m, f = 0.3), are investigated under femtosecond pulse pumping. Fiber F1 supports all-normal dispersion and generates a broadband spectrum from 1.8 to 6.5 & micro;m at 3 kW using a 210 fs pulse. In contrast, fiber F2 yields an anomalous regime SC spectrum spanning 1.5-18 & micro;m under 10 kW peak power and an 85 fs pulse. These findings confirm the applicability of the proposed fibers for MIR applications, such as molecular sensing, spectroscopic analysis, and food quality monitoring.

This paper investigates the generation of an ultrawide spectrum in the mid-infrared region using a suspended-core fiber (SCF) fabricated from As2Se3 chalcogenide glass, in which carbon disulfide is employed as a liquid filling material for three air-holes instead of conventional air. The inclusion of carbon disulfide in the air pores significantly modifies the dispersion characteristics of the optical fiber, enabling a flattened dispersion profile close to zero over a broad wavelength range. Such dispersion-tuning techniques play a crucial role in enhancing nonlinear spectral broadening. Simulation results demonstrate that an ultrawide spectrum spanning from 0.99 mu m to 3.925 mu m can be generated in the proposed SCF, which is only 10 cm long, using a low peak power of 800 W with a pump pulse centered at 2500 nm. The smooth supercontinuum spectrum obtained in the all-normal dispersion regime is expected to exhibit high temporal coherence, as the spectral broadening is primarily influenced by deterministic nonlinear effects such as self-phase modulation and optical wave breaking.

This study investigates how the structural parameters of suspended-core photonic crystal fibers (SC-PCFs) influence their effective refractive index (neff), focusing on designs based on arsenic sulfide (As₂S₃) with carbon disulfide (CS₂)-filled air holes. As₂S₃ provides a high nonlinear refractive index and wide infrared transparency, while CS₂ infiltration enables enhanced optical control due to its high refractive index. Using Lumerical Mode Solutions, numerical simulations were conducted for TE₀₀ and TE₁₀₀ modes across the wavelength range from 2 to 5 μm, with structure ratios (w/ ) varying from 0.35 to 0.85. Results show that neff increases with slot width and reaches 2.2251 at 2150 nm for CS₂-filled designs. Compared to air-filled fibers, CS₂ infiltration improves refractive index control and optical confinement. These results provides quantitative design guidance for optimizing modal confinement and birefringence in SC-PCFs targeting nonlinear and polarization-sensitive applications in the mid-infrared regime.

Large-core optical fibers typically offer the advantages of high input power and improved coupling efficiency at the expense of low nonlinearity and large transmission loss. In this work, we numerically verified that large-core photonic crystal fibers provide high nonlinearity and low confinement loss, enabling broadband mid-infrared supercontinuum generation with nanojoule input pulse energies. The designs use highly nonlinear refractive index Ge25Sb10S65 glass as the substrate material with seven rings of air hole in the cladding arranged in a regular octagonal pattern around the core. The nonlinear propagation in the two proposed fibers is well described by solving the generalized nonlinear Schrödinger equation. Using pump pulses at 3.6 μm with durations of 40 fs and 250 fs and peak powers of 12 kW and 18.5 kW, respectively, two fibers generate supercontinuum bandwidths covering the ranges of 1.921 ̶ 5.698 μm and 1.79 ̶ 9.0 μm under both all-normal and anomalous pump regimes. These compact and stable all-fiber supercontinuum sources, operating at relatively high peak powers, are potentially suitable for medical diagnostic applications due to their arsenic-free nature.

We investigate broadband supercontinuum in the infrared region using octagonal Ga 8 Sb[Formula: see text]S[Formula: see text] photonic crystal fibers by proposing two fiber designs with ultra-flattened all-normal and anomalous dispersion profiles with [Formula: see text][Formula: see text]ps/[Formula: see text] and [Formula: see text][Formula: see text]ps/[Formula: see text] in the wavelength regions of 3.908–8[Formula: see text][Formula: see text]m and 4.077–8.495[Formula: see text][Formula: see text]m, respectively. The first fiber with all-normal dispersion produces supercontinuum bandwidths of 7.532[Formula: see text][Formula: see text]m and 10.314[Formula: see text][Formula: see text]m (30[Formula: see text]dB level) at pump wavelengths of 4.5[Formula: see text][Formula: see text]m and 5.0[Formula: see text][Formula: see text]m, respectively, with a low peak power of 10[Formula: see text]kW due to the combination of the self-phase modulation and stimulated Raman scattering. With three zero dispersion wavelengths, the second fiber enables a supercontinuum bandwidth of 11.536[Formula: see text][Formula: see text]m (30 dB level) at the pump wavelength of 5.0[Formula: see text][Formula: see text]m with a peak power of 8[Formula: see text]kW under the influence of soliton dynamic suppression. These results, as a platform for developing broadband supercontinuum sources, are required for applications in the infrared region.

We numerically investigated the supercontinuum (SC) generation process in a chalcogenide Ge20Sb5Se75 suspended core photonic crystal fiber (SCF) with air holes filled with carbon disulfide (CS2). The influence of the ratio of the bridge width to the core radius (w/rc) on the dispersion characteristics of SCF was investigated for both x- and y-polarized modes, and the results were compared with those of an unfilled SCF. By optimizing the SCF geometry, a flat normal dispersion profile was achieved and used for SC studies in the considered wavelength range. The results show that when pumping a light source at 2 μm with an input pulse of 0.084 nJ and a width of 120 fs into a 10 cm fiber length, a SC spectrum spanning from 1 to 3 μm can be generated. The broad spectrum makes it highly suitable for mid-infrared applications such as bio-imaging, optical coherence tomography, and sensing.

The proposed design offers two flat near-zero dispersion profiles by appropriately adjusting the air-hole pitch and diameter in the cladding of a circular silica photonic crystal fiber with a tetrachloroethylene-infiltrated core. The broad supercontinuum spectrum of 0.794–2.435 and 0.916–3.1 μm in the mid-infrared is achieved using two optimized fibers with all-normal and anomalous group-velocity dispersion, respectively, at 1.55 μm pump wavelength. The peak powers of 3.0 and 2.5 kW meet the requirements of compact, low-power supercontinuum sources, ideal for applications such as spectroscopic measurement, frequency metrology, and biomedicine.

We investigate broadband supercontinuum in the infrared region using octagonal Ga8Sb32S60 photonic crystal fibers by proposing two fiber designs with ultra-flattened all-normal and anomalous dispersion profiles with Delta D = +/- 5.145ps/nm & sdot;km and +/- 4.723ps/nm & sdot;km in the wavelength regions of 3.908-8 mu m and 4.077-8.495 mu m, respectively. The first fiber with all-normal dispersion produces supercontinuum bandwidths of 7.532 mu m and 10.314 mu m (30dB level) at pump wavelengths of 4.5 mu m and 5.0 mu m, respectively, with a low peak power of 10kW due to the combination of the self-phase modulation and stimulated Raman scattering. With three zero dispersion wavelengths, the second fiber enables a supercontinuum bandwidth of 11.536 mu m (30 dB level) at the pump wavelength of 5.0 mu m with a peak power of 8kW under the influence of soliton dynamic suppression. These results, as a platform for developing broadband supercontinuum sources, are required for applications in the infrared region.

In silica fiber supercontinuum generation, obtaining both broad spectral bandwidth and high coherence is still challenging, particularly in the 1.55 μm telecommunications window. Here, a simplified four-ring silica photonic crystal fiber infiltrated with nitrobenzene is proposed and numerically investigated. Ultra-flat chromatic dispersion is achieved through optimization of a small set of structural parameters, allowing the generation of supercontinua in both the all-normal dispersion (ANDi) and anomalous dispersion (AnD) regimes. Using 60 fs and 180 fs pump pulses, the proposed ANDi and AnD designs generate 1.51- and 2.23-octave supercontinua, respectively, at peak powers of 130 W and 200 W. Spectral coherence is evaluated through 200 stochastic simulations under different noise conditions. The ANDi fiber maintains high coherence, with an average first order coherence of g121= 0.956 over the 1.3–1.8 μm wavelength range and coherence exceeding 0.95 across approximately 2.3 μm of bandwidth, indicating its potential for high resolution optical coherence tomography. Meanwhile, the extended spectral coverage achieved in the AnD regime provides access to the mid-infrared region relevant to molecular absorption spectroscopy. This work provides useful design guidelines for broadband, low power supercontinuum sources based on liquid-infiltrated simplified silica PCFs operating at the 1.55 μm telecommunications wavelength.

Supercontinuum (SC) generation with broad spectral coverage in the near-infrared (IR) and mid-IR ranges is critical for applications such as medical diagnostics, biomedical sensing, and optical coherence tomography. In this study, we demonstrate SC generation in a 10 cm lead-bismuth-gallate dual-core photonic crystal fiber (DC-PCF), where the structural symmetry ensures that the dispersion curves of all four supermode components are nearly identical. Using the generalized nonlinear Schrödinger equation (GNSE), we analyze how pump wavelength, peak power, and pulse width influence the resulting SC spectra. Pumping at 1560 nm, within the normal dispersion regime, and with a peak power of 30 kW, produces a broadband SC spanning 1275.8-2475.8 nm (1200 nm bandwidth) at 30 dB. In contrast, pumping in the anomalous dispersion regime at 1950 nm with the same peak power yields an SC bandwidth of 2353 nm at 30 dB. This bandwidth increase, compared to those of a single-core PCF under identical conditions, results from enhanced nonlinear mixing and inter-core energy transfer, which are facilitated by the intermodal interference of the supermode components in the DC-PCF. The proposed DC-PCF can be fabricated using conventional stack-and-draw techniques, making it a promising candidate for the development of coherent SC light sources.

This paper presents a numerical study on the optimization of square lattice silica photonic crystal fibers with variable pitch and a C2Cl4-infiltrated core, aiming to achieve tailored dispersion characteristics for efficient midinfrared supercontinuum generation at 1.55 mu m wavelength. The square cladding structure is known as an effective solution for generating smooth, flat-top SCGs, suitable for optical tomography applications. The first fiber has an ultra-flat all-normal dispersion profile with Delta D = +0.889 ps/nm & sdot;km over a wavelength range of 0.352 mu m. When pumped with 40 fs pulses at an input energy of 0.12 nJ, this fiber generates supercontinuum spectrum spanning from 0.811 to 2.44 mu m (approximately 1.6 octaves), driven primarily by self phase modulation and optical wave breaking. The second fiber provides flat anomalous dispersion (Delta D = +7.573 ps/nm & sdot;km over the same wavelength range as the first fiber), with a low dispersion value of 2.448 ps/nm & sdot;km at 1.55 mu m. It supports soliton induced supercontinuum with a spectrum covering 0.788 to 3.673 mu m (more than two octaves) using a pump pulse of 120 fs duration and an input energy of 0.48 nJ. These optimized fibers demonstrate strong potential for the realization of compact, cost effective supercontinuum generation sources applicable to midinfrared nonlinear applications.

Liquid-core fibers, which are hollow core fibers or capillaries filled with liquids as core materials, have been attractively explored for various applications, especially in nonlinear optofluidics. High nonlinear refractive indices of selected liquids enable broadband supercontinuum generation. Unlike solid glasses, the nonlinear properties of liquids are more complex, including a contribution of electro-bound (instantaneous) nonlinearity and molecular rotation and vibration under external laser pulses (i.e., noninstantaneous nonlinearity). While the role of noninstantaneous nonlinearity in pulse evolution under anomalous dispersion has been extensively studied, its effect on pulse broadening in normal dispersion regimes remains unexplored. In this work, we numerically simulate pulse evolution in a liquid-core fiber with normal dispersion and high noninstantaneous nonlinearity. The results point out that this nonlinearity leads to narrow bandwidth and asymmetry spectrum of self-phase modulation and enhances simulated Raman scattering even at a low input power. High nonlinearity of the liquid provides an octave spanning supercontinuum generation (e.g., 1050-2700 nm with 1 kW input peak power and 20 ps input pulse-width); however, noninstantaneous nonlinearity significantly decreases the coherence through simulated Raman scattering. These results are valuable for understanding light-liquid interactions, not only for supercontinuum generation but also for applications in optofluidic lasers and sensors.

Solid-core photonic crystal fibers (PCFs) made of Ge20Sb5Se75 glass with square, circular, and hexagonal lattices are proposed to generate mid-infrared supercontinuum (SC) sources. Optical characteristics including dispersion, effective mode area, confinement loss, and nonlinear coefficient of the fundamental mode are investigated numerically. As a result, three optimized PCFs are chosen and compared SC generation efficiency. The dispersion characteristics of all three structures are normal for SC generation with a smooth spectrum. This process is conducted for the pump wavelength of 3.25 mu m. We have obtained multi-octave SC with 210 fs pulse and 3.81 kW peak power in the proposed fibers. Square lattice PCF with a near-zero flattened dispersion curve, small dispersion, and low confinement loss provides the widest SC bandwidth of 1.48-4.98 mu m. Meanwhile, the broad SC spanning from 1.35 mu m to 4.7 mu m is achieved in hexagonal PCF with the highest nonlinear coefficient. The spectrum covers the wavelength range of 1.43 mu m-4.68 mu m for circular-shaped fiber. Proposed fibers with their advantage of large core size, ultraflat spectrum, and low peak power can result in a low-cost all-fiber SC generation system and excellent coupling efficiency with standard fibers.

A novel and simple structure of nitrobenzene-filled hexagonal core photonic crystal fibers with supercontinuum spectral broadening in the mid-infrared region is numerically simulated. We can optimize geometrical parameters such as pitch, larger and smaller air hole diameters, hollow core shape to control and design dispersion characteristics, achieving an all-normal near zero flattened dispersion with fluctuation of +/- 1.807 ps/nm center dot km in the 0.431 mu m wavelength range and low value of -2.496 ps/nm center dot km at the 1.55 mu m pump wavelength. The two proposed fibers have small effective mode areas leading to high nonlinear coefficients, with values of 8966.877 and 7311.825 W-1.km-1, respectively, at the pump wavelength of 1.55 mu m. At 370 W of pump power, a nearinfrared supercontinuum spanning from 0.791 to 2.99 mu m with a bandwidth at 30 dB of 1.726 mu m is obtained using the first fiber with an all-normal dispersion profile. Soliton dynamics govern the expansion of the supercontinuum spectrum into the mid-infrared region when the second fiber is pumped at a wavelength of 1.55 mu m in an anomalous dispersion regime, covering from 0.791 to 6.5 mu m (bandwidth of 3.49 mu m at 30 dB) with a peak power of 500 W. These numerical results can be useful for various purposes such as biomedical, sensors, and optical coherence tomography.

This paper proposes two novel photonic crystal fibers (PCFs) with a nitrobenzene core, designed using hexagonal and square lattice structures. The characteristics of the PCFs were numerically analyzed in detail and compared to selecting the proposed optimal structure for supercontinuum generation. This study investigates the influence of core diameter (DC) on the characteristics of PCF. The fiber’s nonlinear properties are significantly enhanced by varying the core diameter. The hexagonal PCF structures provide flatter dispersion curves and are closer to zero dispersion than the square lattice, which is beneficial for supercontinuum generation. In contrast, the square PCF structures show higher nonlinear coefficients and lower attenuation than the corresponding hexagonal structures. Based on the simulation results, six optimized structures with all-normal and anomalous dispersion were selected to study the characteristics at the pump wavelength. Results indicate that the proposed PCFs exhibit near-zero flat dispersion, low attenuation and high nonlinearity. The selected optimal structures show potential for efficient supercontinuum generation, enabling broad and highly coherent spectra.

An enhanced group velocity dispersion (GVD) control with suspended core fiber (SCF) has been investigated using numerical simulation based on the finite element method. It requires an SCF made of lead-bismuth-gallium-oxide glass with three air holes filled with carbon disulfide (CS2). Unlike unfilled fibers, CS2-filled SCFs can achieve small slopes of the effective refractive index curves using the fundamental modes, resulting in flat group velocity dispersion in the low group velocity region. We also found that the ratio between the width of the bridge and the core radius can affect the shift of the zero-dispersion wavelength. The proposed SCFs show excellent performance in achieving low anomalous GVD, which can offer higher efficiency in supercontinuum spectral flattening. Additionally, the structures with small normal GVD values are promising candidates for pulse stretching due to the exact balance between nonlinear effects and dispersion.

Three distinct configurations of As2S3 chalcogenide photonic crystal fibers (PCFs) were designed to investigate supercontinuum generation (SCG). The optical properties of PCFs with the circular lattice (CL), square lattice (SL), and hexagonal lattice (HL) were comprehensively analyzed to choose the optimal fiber for SCG. This investigation facilitated the identification of three superior structures, specifically designated as #CF, #SF, and #HF, respectively. These structures are unified by operating within an all-normal dispersion regime, each presenting a lattice constant of 1.0 μm and a filling factor of 0.35. These fibers were subjected to a peak power of 4.0 kW and a pulse duration of 270 fs, culminating in an expansive supercontinuum range. Notably, the SC range extended from 2.0 to 6.5 μm for #CF, from 2.0 to 8.3 μm for #SF, and from 1.9 to 6.6 μm for #HF. The SL-PCF exhibited the broadest supercontinuum, attributed to its protracted flat dispersion band. Furthermore, compared to previously reported all-normal dispersion PCFs, the spectral range facilitated by this peak power was significantly augmented. These optical fibers promise to provide supercontinuum spectra with broad bandwidth for practical applications in sensing and gas detection.

This paper proposes two novel photonic crystal fibers (PCFs) with a nitrobenzene core, designed using hexagonal and square lattice structures. The characteristics of the PCFs were numerically analyzed in detail and compared to selecting the proposed optimal structure for supercontinuum generation. This study investigates the influence of core diameter (DC) on the characteristics of PCF. The fiber’s nonlinear properties are significantly enhanced by varying the core diameter. The hexagonal PCF structures provide flatter dispersion curves and are closer to zero dispersion than the square lattice, which is beneficial for supercontinuum generation. In contrast, the square PCF structures show higher nonlinear coefficients and lower attenuation than the corresponding hexagonal structures. Based on the simulation results, six optimized structures with all-normal and anomalous dispersion were selected to study the characteristics at the pump wavelength. Results indicate that the proposed PCFs exhibit near-zero flat dispersion, low attenuation and high nonlinearity. The selected optimal structures show potential for efficient supercontinuum generation, enabling broad and highly coherent spectra.

This study investigates large-core photonic crystal fibers (PCFs) composed of As2S3 chalcogenide for their potential in supercontinuum (SC) generation owing to their tunability in terms of chromatic dispersion, nonlinearity, and loss characteristics. We compare SC generation spectra within an all-normal dispersion regime across three lattice geometries: hexagonal, circular, and square. The numerical simulations employed peak power and pulse width values of 5.83 kW and 120 fs, respectively. These pump source parameters resulted in mid-infrared SC ranges ranging from 2 to 6.9 μm for hexagonal, 2.15–7 μm for circular, and 2.2–8.1 μm for square lattices. Notably, the square lattice configuration yielded the broadest SC spectrum, attributed to its extensive flat dispersion band, whereas the circular lattice design achieved the flattest spectrum with 4 dB variation in the 1.79 μm band at the pump wavelength close to the maximum dispersion point. Furthermore, at low peak power, these spectral ranges surpass those reported for all-normal dispersion PCFs in previous studies. The proposed structures are promising for applications in low-peak power all-fiber optical systems.

This work presents a polarization-maintaining (PM) highly nonlinear Ge 20 As 20 Se 15 Te 45 chalcogenide photonic crystal fiber (PCF) designed for broadband mid-infrared (MIR) supercontinuum (SC) generation. Through optimization of the PM-PCF’s geometrical parameters, the proposed fiber exhibits ultra-flat normal dispersion properties for the fundamental mode with the x -polarization component. In contrast, the y -polarization fundamental mode, the proposed PCF provides flat anomalous dispersion properties at a pump wavelength of 9.8 μ m. The effects of input energy and pulse width on the spectral profiles and coherence properties of the SC spectrum are investigated. The result is a highly coherent SC extending from 4.98 µ m to 15.08 µ m (a bandwidth of 10.1 µ m) and from 2.9 µ m to 25.2 µ m (a bandwidth of 22.45 µ m) in the MIR region when a pump pulse with a wavelength of 9.8 μ m is used for the designed fiber with the x -polarization and y -polarization factors, respectively. The proposed PM-PCF-based SC source shows potential as a candidate for nonlinear applications, including frequency metrology, optical sensing, and optical tomography.