Broadband Supercontinuum Generation Research Articles

Ge-Se-Te based penrose photonic quasi-crystal fiber for SCG covering 2–21 μm MIR regime

This work proposes a Penrose-based photonic quasi-crystal fiber (PQF) composed of Arsenic-free, non-toxic chalcogenide glass for Supercontinuum (SC) generation consisting of quasi-crystal lattice of air holes having eight-fold rotational symmetry. Following optimizing the structural parameters, the proposed PQF offers zero dispersion wavelength (ZDW) at around 3.8 μm, an effective mode area of 30 μm2, and a respective high nonlinearity of 824 W−1Km−1 at 2 μm wavelength. By injecting a secant hyperbolic optical pulse having a central wavelength of 4 μm with 20 kW peak power and pulse width of 50 fs, a broadband SC of 2–21 μm is generated, which mostly covers the transparency range of the proposed material as well as Mid-IR regime. To the best of our understanding, this particular type of PQF for broadband SC generation has been proposed for the first time, serving as the novelty factor. Apart from novelty, the wide-band SC assists the proposed PQF in becoming a better counterpart for applications like optical coherence tomography (OCT), frequency metrology, and other Mid-IR applications.

Dispersion tailored suspended core SiN channel waveguide for broadband supercontinuum generation

Dispersion tailored suspended core SiN channel waveguide for broadband supercontinuum generation

Numerical Investigation of Optical Properties in Carbon Tetrachloride-Filled Photonic Crystal Fibers

In this work, we design circular lattice photonic crystal fibers using Lumerical Mode Solution software, its hollow core filled with carbon tetrachloride. Optical properties including effective refractive index, chromatic dispersion, nonlinearity, and fiber loss were investigated numerically in detail based on solving Maxwell's wave equations. The small effective mode areas of only a few µm2, and confinement loss as low as 14.799 dB/m at specific pump wavelengths were obtained. It was found that near-zero ultra-flattened chromatic dispersion with fluctuations of ±0.44 ps/nm.km spans from 1300 to 1830 nm. Three photonic crystal fibers with optimal structure and features were suggested for broadband supercontinuum generation orientation.

Enhanced spectral broadening via the optical rogue wave stimulated by spectral sinusoidal phase

We numerically investigate the extended spectral broadening via a spectral sinusoidal phase-modulated Gaussian pulse. The modulated pulse can create two predominant solitons that collide with each other to form a rogue wave (RW), resulting in an RW-induced dispersive wave emission. This leads to a further spectral broadening beyond the soliton-induced dispersive wave and can be manipulated by tuning the phase modulation parameters. Before the appearance of RW, the modulated pulse-propagation scenario is governed by the optical Newton’s cradles and the optical event horizons. These complex dynamics reveal a new method for controlling the RW generation as well as spectral broadening at relatively low power levels. Our results have potential implications for controllable excitation of RWs and broadband supercontinuum generation.

Broadband supercontinuum generation in hollow-core photonic crystal fibers infiltrated with chloroform

The chloroform-infiltrated square lattice photonic crystal fibers (PCFs) are designed with the difference of the air hole diameters in the cladding to improve chromatic dispersion and nonlinear properties. Based on numerical simulation results, two optimal structures with flat dispersion, high nonlinear coefficient, and small confinement loss are used for supercontinuum (SC) generation. The first fiber has an all-normal dispersion regime, a nonlinear coefficient of 486.355[Formula: see text]W[Formula: see text].km[Formula: see text] generating an SC spectrum of 640.3[Formula: see text]nm within 30 dB levels at a pump wavelength of 0.945[Formula: see text][Formula: see text]m with peak power as low as 1.44[Formula: see text]kW. With anomalous dispersion properties, the second fiber gives a very broad SC spectrum of 1471.8[Formula: see text]nm within 30 dB levels at a 1.4[Formula: see text][Formula: see text]m pumping wavelength with a peak power of 20[Formula: see text]kW. All-fiber SC sources operating with low-power pump lasers can use these fibers to effectively replace glass-core fibers.

Supercontinuum generation in As2S3 chalcogenide waveguide pumped by all-fiber structured dual-femtosecond solitons.

Supercontinuum sources with high compactness are essential for applications such as optical sensing, airborne detection and communication systems. In the past decades, the adoption of bulky optical parametric amplifier to pump various chalcogenide glass waveguides are widely reported for on-chip mid-infrared supercontinuum generation, but this usually leads to a large volume of the whole system, and is not practical. Therefore, integrating advanced femtosecond fiber lasers with optical waveguides using nano-fabrication technology are highly desired. However, the scarcity of compact pump sources and the dispersion-matched high-nonlinearity waveguide in short wavelength regions have hindered the advancement of integrated supercontinuum source performances in the near and mid-infrared region. In this study, we demonstrate a broadband supercontinuum source from As2S3 waveguide pumped by a compact dual-femtosecond solitons pulse source. The laser is completely fiber structured, and its wavelength can be readily tuned from 2 to 2.3 µm using Raman soliton self-frequency shift technology in a Tm3+-doped fiber amplifier. Furthermore, the As2S3 waveguide is designed with controllable dispersion and high nonlinearity for a broadband supercontinuum generation. These results will advance the development of on-chip supercontinuum sources based on chalcogenide waveguides.

Broadband supercontinuum generation with low peak power in controllable C7H8-core photonic crystal fibers of characteristic quantities

Broadband supercontinuum generation with low peak power in controllable C7H8-core photonic crystal fibers of characteristic quantities

Broadband supercontinuum generation in a square lattice photonic crystal fiber with C6H6-core using low pump power

Broadband supercontinuum generation in a square lattice photonic crystal fiber with C6H6-core using low pump power

Tunable Dispersion and Supercontinuum Generation in Disordered Glass-Air Anderson Localization Fiber

In this paper, we discuss chromatic dispersion properties of transverse Anderson localization optical fiber (TALOF) and their implications on broad band supercontinuum (SC) generation. Our dispersion study reveals a clear correlation between the Anderson localization length and the dispersion properties of highly localized TALOF modes. We demonstrate that the zero dispersion wavelength can be tuned over more than 300 nm within the same fiber by selected excitation of specific modes. We exploit this unique TALOF property, which we validated with rigorous finite-element modeling, to generate multi octave spanning SC ranging from 460–1750 nm, highlighting the great potential of disordered Anderson localization fibers for nonlinear applications.

Broadband supercontinuum generation in cascaded tapered liquid core fiber

Most recent broad supercontinuum sources have used nonlinear fibers with small core diameters, resulting in low coupling efficiency, limiting power level launching into the fiber, and low spectral power density. In this work, we numerically investigate tapered liquid-core fibers for supercontinuum generation that have a potential for both high coupling efficiency (with a standard SMF-28 fiber) and high nonlinear effects. Carbon disulfide is selected to fill into the fibers because of its high nonlinear refractive index and high transparency from the visible to the mid-infrared range. We consider cascaded fibers including SMF-28 and the tapered liquid-core fibers for all-normal and anomalous dispersion supercontinuum generation pumped by C-band femtosecond lasers (1560 nm, 90 fs). In such a case, we obtain all-normal dispersion supercontinuum generation with flat-top, broad bandwidth (1.0–2.5μm) via an input peak power of 27 kW. By changing the core diameter of the tapered fiber, we also yield anomalous dispersion supercontinuum generation with broad spectral bandwidth (1.0–3.3μm). In addition, the use of the cascaded tapered fibers is possible to mitigate fiber damage (via thermal effects of a high-power laser on the selected liquids) and increase stability of output supercontinuum spectra. In this context, supercontinuum generation in the cascaded fibers by using a picosecond laser with high average power (≈ 800 mW) is considered towards applications requiring high spectral power density (e.g., multiphoton imaging techniques).

Manipulating dispersive wave emission via temporal sinusoidal phase modulation.

We report the dispersive wave (DW) emission from the Gaussian pulse with temporal sinusoidal phase (TSP) modulation. The TSP-induced chirp can enhance or cancel the chirp generated by self-phase modulation by properly selecting the modulation parameters of TSP, which can influence the nonlinear propagation of the TSP-modulated pulse. It is shown that the TSP can effectively control the resonant frequency and energy conversion efficiency of the DW emission. We give a modified phase-matching condition to predict the resonant frequencies, which agree with the simulation results obtained by numerically solving the nonlinear Schrödinger equation. The enhanced conversion efficiency of the DWs can be increased up to 28% with only TSP modulation. Our results can extend the application of temporal phase modulation technology for wavelength conversion, and broadband supercontinuum generation.

Flat-top and broadband supercontinuum generation in CCl4-filled circular photonic crystal fiber

In this work, a flat-top and broadband supercontinuum (SC) generation in photonic crystal fibers (PCFs) infiltrated with carbon tetrachloride (CCl[Formula: see text] with different air hole diameters in the cladding has been introduced. The optical properties of the fundamental mode are analyzed by numerical simulation. Based on the obtained results, two optimized PCFs with small dispersion are proposed and verified against SC generation in detail. The first fiber has an all-normal dispersion of [Formula: see text]9.376[Formula: see text]ps.nm[Formula: see text].km[Formula: see text] at the pump wavelength of 0.98[Formula: see text][Formula: see text]m, generating broadband of 768[Formula: see text]nm and flat-top with only 0.3[Formula: see text]nJ of input energy and time duration of 90[Formula: see text]fs. In the meantime the dispersion property of the second fiber is anomalous, which equals 1.105[Formula: see text]ps[Formula: see text][Formula: see text][Formula: see text]nm[Formula: see text][Formula: see text][Formula: see text][Formula: see text]km[Formula: see text] at 1.3[Formula: see text][Formula: see text]m pump wavelength. The second fiber generates a SC spectrum of 1,751.1[Formula: see text]nm with input energy and time duration of 0.55[Formula: see text]nJ and 55[Formula: see text]fs, respectively. Proposed fibers are suitable for all-fiber SC sources which could lead to new low-cost all-fiber optical systems.

A study on the optical properties of a novel flower-core photonic crystal fiber infiltrated with CCl4

A novel design of photonic crystal fiber with a flower-core is proposed for the first time to optimize dispersion suitable for broadband supercontinuum generation. The numerical simulation of the propagation of light modes in optical fibers is computed by solving Maxwell's wave equations with the full-vector finite-difference eigenmode method. As a result, near-zero ultra-flat all-normal and anomalous dispersion was achieved with fluctuations of ±0.978 ps/nm.km in the 294 nm wavelength region and ±1.168 ps/nm.km in the 432 nm wavelength region, respectively. Furthermore, the dispersion value at the pump wavelength is about 10 times lower than in previous papers. The combination of CCl4 infiltration into the hollow core and the air hole's size heterogeneity in the cladding also enhances the nonlinear properties of the fibers. The effective mode areas less than 2 µm2 at the pump wavelength can help the supercontinuum spectrum to broaden further towards the red wavelength region. Three fibers with structural parameters Ʌ = 0.8 µm, d1/Ʌ = 0.45, Ʌ = 0.9 µm, d1/Ʌ = 0.5, and Ʌ = 0.9 µm, d1/Ʌ = 0.45 are proposed for supercontinuum generation with low peak power due to the nonlinear coefficients as high as hundreds W−1.km−1. These fibers are a new class of optical fibers, highly efficient laser sources that replace traditional glass-core optical fibers.

Fabrication of ultra-high numerical aperture GeO2-doped fiber and its use for broadband supercontinuum generation: publisher's note.

This publisher's note serves to correct Appl. Opt.56, 9315 (2017)APOPAI0003-693510.1364/AO.56.009315.

Highly coherent supercontinuum generation in circular lattice photonic crystal fibers using low-power pulses

Two structures of circular lattice Photonic Crystal Fibers (PCFs) based on Ge20Sb15Se65 (GSS) material have been proposed for a highly coherent broadband supercontinuum generation (SCG) in the mid-infrared region. Numerical studies using the Finite Difference Eigenmode (FDE) solver on both structures show that the fundamental modes are well confined in the core while the confinement losses are very low. Also, the high nonlinear coefficient of 22.01 W−1m−1 and 17.99202 W−1m−1 for the two structures ensure that these structures can accomplish high nonlinear activity. It has been found that broadband supercontinuums (SCs) spanning from 0.45 μm to 5.3 μm and 0.48 μm to 6.5 μm can be generated using a hyperbolic secant pulse of 0.5 kW. The proposed structures also show very good structural tolerance to optical properties that prevents any radical shift in SC spectra owing to potential fabrication mismatch.

Mutual manipulation between a dark soliton and an Airy pulse at the optical event horizon

A fiber-optical analog of the event horizon is proposed via the collision dynamics between a dark soliton and an Airy pulse for the first time, under the effect of soliton-induced Kerr nonlinear effect. An Airy wave packet is more effective in manipulating the properties of a dark soliton than a Gaussian-like pulse in the regime of the optical event horizon since the Airy-soliton horizon can be regarded as the successively isolated horizon processes. Besides, the initial chirp and attenuation factor are two key regulators of the Airy pulse, which can not only adjust the flatness and width of the output spectrum during the collision process but also modify the properties of the output dark soliton. The interesting dynamic investigated in this work as a process of mutual manipulation can be considered as a promising candidate for frequency conversion and broadband supercontinuum generation, which proves the theory basis for further understanding of the light-by-light controlling in a more controllable manner.

Broadband Supercontinuum Generation in Dispersion Decreasing Fibers in the Spectral Range 900–2400 nm

The spectrally flat supercontinuum generation in the wavelength range of 900–2400 nm is demonstrated in silica-based fibers of variable core diameter and dispersion. It is shown that, in comparison with standard optical fibers of the same length, supercontinuum spectra 200 nm wider can be realized in the samples under study. The significant difference between the spectral and temporal transformations of radiation depending on the direction of propagation is demonstrated in the researched fiber samples.

INFLUENCE OF STRUCTURAL PARAMETERS ON OPTICAL CHARACTERISTICS OF PHOTONIC CRYSTAL FIBERS WITH CIRCULAR LATTICE

We demonstrate in this study that near-zero, ultra-flattened chromatic dispersion can be achieved over a wide range of wavelengths in photonic crystal fibers (PCFs) by means of slight variations in the geometrical parameters of the cladding. To do that, a new solid-core circular PCF design with various air hole diameters and lattice constants is presented, and the design features are numerically analyzed in detail. After 40 simulations, we determined three structures that possess optimal dispersion with the following lattice constants (Ʌ) and filling factors for the first ring (d1/Ʌ): Ʌ = 0.8 µm, d1/Ʌ = 0.45 for #F1, Ʌ = 0.9 µm, d1/Ʌ = 0.45 for #F2, and Ʌ = 1.0 µm, d1/Ʌ = 0.45 for #F3. High nonlinearity and low attenuation are outstanding features of our model. With these advantages, the proposed fibers are targeted for smooth flat broadband supercontinuum generation for near-infrared applications.

Engineering the high-frequency components of coherent supercontinuum generation in hybrid optical fibers with yttrium aluminum garnet core

Coherent supercontinuum (SC) generation in optical fibers has spurred extensive research interest and found many applications. Here, we report a hybrid optical crystal fiber with an yttrium aluminum garnet (YAG) core. The optimized fiber features broad and flat near-zero normal dispersion and three wavelengths where the dispersion slope is zero. Through numerical modeling, we in detail investigate the influence of the pump wavelengths near the three wavelengths on the spectral broadening. The spectral broadening shows asymmetric towards the high-frequency region. The longer the pump wavelength, the more is the short wavelength components of the generated SC. Thus, the high-frequency components of the SC spectra can be engineered in the fiber. Interestingly, the occurrence of optical wave breaking (OWB) in the low-frequency region is prior to that in the high-frequency region when the pump wavelength is at 1660 nm. The broadest spectrum could be obtained when the pump wavelength is near the middle wavelength where the dispersion slope is zero. The result provides a new strategy for fiber design and broadband SC generation, which is different from the viewpoint that the broadest spectrum can be obtained when the pump wavelength near the local maximum dispersion. Combined with high nonlinearity and flat dispersion, the hybrid fiber allows octave-spanning SC generation with the pump power low to 1 kW at 1100 nm. This provides the potentials for high-power, broadband, and coherent SC generation at 1064 nm where the dispersion slope is near zero.

Interactions of the second-order solitons with an external probe pulse in the optical event horizon

We demonstrate manipulating the interactions of a second-order soliton with a weak probe pulse under the condition of group velocity match and group velocity mismatch (GVMM). During these interactions, the second-order soliton acting as an effective periodic refractive-index barrier leads to the polychromatic scattering of the probe pulse, which is represented as unequally spaced narrow-band sources with adjustable spectral width. In the case of GVMM, almost all the spectral components of the narrow-band sources meet the nonlinear frequency conversion relationship by using the wavenumber-matching relationship due to the robustness of the second-order soliton under moderate high-order-dispersion perturbations, so this case is more conducive to the study of the soliton wells. In addition, different transmission states of a soliton well are demonstrated under different probe pulse properties in the fiber-optical analog of the event horizon. When the power of the probe pulse is strong enough, a dispersive wave can be generated from the collision of two fundamental solitons split from the two second-order solitons. These interesting phenomena investigated in this work as a combination of white- and black-hole horizons can be considered as promising candidates for frequency conversion and broadband supercontinuum generation.