Pulses In Photonic Crystal Fibers Research Articles

Propagation dynamics of hollow Gaussian pulse in photonic crystal fiber

Propagation dynamics of hollow Gaussian pulse in photonic crystal fiber

Controllable multi-soliton spectral tunneling by airy pulses in photonic crystal fiber

A straightforward method to induce tunable multi-soliton spectral tunneling (SST) using a finite energy Airy pulse in a photonic crystal fiber (PCF) featuring three zero-dispersion wavelengths is proposed numerically in the paper. The study reveals that the distinctive multi-envelope structure of the Airy pulse enables the control of tunneling distances, properties, and soliton numbers through modulation of its attenuation factor and peak intensity. Notably, the SST process involving the Airy pulse generates multiple blue-shifted and red-shifted dispersion waves, along with associated trapping waves, contributing to the formation of an ultra-flat and ultra-wide supercontinuum. Furthermore, the velocity and efficiency of multi-SST can be manipulated to enhance the overall tunability of the phenomenon. The findings underscore the potential application of Airy pulse-driven SST in secure multi-frequency signal transmission and controlled supercontinuum generation, with the tunability of these processes being governed by the specific attenuation factor and peak power settings of the input Airy pulse. This work advances the understanding of multi-SST dynamics in PCFs and provides a theoretical framework for exploiting these dynamics in practical information security and optical spectrum management contexts.

Supercontinuum Generation from Airy-Gaussian Pulses in Photonic Crystal Fiber with Three Zero-Dispersion Points

The supercontinuum generation and manipulation of Airy-Gaussian pulses in a photonic crystal fiber with three zero-dispersion points are studied using the split-step Fourier method. Firstly, the spectral evolution of Airy-Gaussian pulses in four photonic crystal fibers with different barrier widths was discussed, and the optimal fiber was determined after considering the factors of width and flatness. By analyzing the mechanism of supercontinuum generation in photonic crystal fibers with single, double and three zero-dispersion points, it is found that the photonic crystal fiber with three zero-dispersion points have a larger spectral width due to the component of tunneling solitons. Then, the effects of four characteristic parameters (truncation factor a, distribution factor χ0, initial chirp C and central wavelength λ) on forming the supercontinuum spectrum of Airy-Gaussian pulses are analyzed in detail. The results show that the spectral width and energy intensity of the dispersive wave and tunneling soliton generation can be well controlled by adjusting the barrier width and initial parameters of the pulse. These research results provide a theoretical basis for generating and manipulating high-power mid-infrared supercontinuum sources.

Effect of Some Parameters on Optical Soliton Pulses in Photonic Crystal Fibers

Fiber optics have been greatly enhanced by photonic crystal fibers based on microstructured air-glass designs. On the one hand, such fibers enable very tight light confines in a small mode shape region, resulting in significantly improved alternative options between light and dielectric medium. Photonic crystal fibers, on the other hand, allow light to be guided via air core instead of glass. As a result, the latter form of fiber decreases optical nonlinearities in ways that classic fiber designs cannot. The chirp effect and dispersion of photonic crystal fibers with super-Gaussian pulses during various pulses durations are examined in this paper in both normal and anomalous dispersion patterns. The chirp effect and fiber dispersive nonlinear effects are investigated. For this study, a mathematical model of the solution of a nonlinear equation involved the split-step Fourier method. Peak power was reduced for broad pulses. When the magnitude of the super-Gaussian pulse increased proportionally, pulse constriction was also noticeable, Furthermore, the results reveal that an anomalous dispersion system was superior to a regular dispersion system for pulse . The experimental findings will facilitate further research into more understanding of photonic crystal fibers, and to improve data speeds in modern optical communication systems

Evolution of Airy-Gaussian pulses in photonic crystal fiber with two zero-dispersion wavelengths

We numerically investigate the evolution of Airy-Gaussian (AiG) pulses in photonic crystal fiber with two zero-dispersion wavelengths. Firstly, in the absence of higher-order nonlinear effects, the effects of three essential parameters of AiG pulses (truncation coefficient, distribution factor, and initial chirp) on the pulse evolution are studied in detail. The results indicate that initial AiG pump pulses with a small truncation coefficient, small distribution factor, and positive chirp are beneficial for obtaining a wider supercontinuum spectrum. Moreover, we further take stimulated Raman scattering (SRS) and self-steepening (SS) effects into account, and find that SRS greatly broadens the output spectrum when AiG pulses with a small distribution factor (χ0 = 0.1), however, it also leads to obvious spectrum collapse and the collapse will be reduced to a certain extent due to SS.

Generation of wideband tunable femtosecond laser based on nonlinear propagation of power-scaled mode-locked femtosecond laser pulses in photonic crystal fiber* *Project supported by the National Natural Science Foundation of China (Grant No. 61805274), the Major Program of the National Natural Science Foundation of China (Grant No. 12034020), and Research Foundation of Inner Mongolia University of China (Grant No. 21200-5215108).

We implement an experimental study for the generation of wideband tunable femtosecond laser with a home-made power-scaled mode-locked fiber oscillator as the pump source. By coupling the sub-100 fs mode-locked pulses into a nonlinear photonic crystal fiber (NL-PCF), the exited spectra have significant nonlinear broadening and cover a spectra range of hundreds of nm. In experiment, by reasonably optimizing the structure parameters of NL-PCF and regulating the power of the incident pulses, femtosecond laser with tuning range of 900–1290 nm is realized. The research approach promotes the development of femtosecond lasers with center wavelengths out of the traditional laser gain media toward the direction of simplicity and ease of implementation.

The Propagation Characteristics of Femtosecond Pulses in Photonic Crystal Fiber

In this paper, the propagation characteristics of femtosecond pulse in Photonic crystal fiber (PCF) are described in detail. In this paper, we simulate the nonlinear Schrodinger equation by using the step-by-step Fourier method, and analyze the generation process of supercontinuum spectrum.

Chaotic dynamics and supercontinuum generation with cosh-Gaussian pulses in photonic-crystal fibers

In this paper, we investigate broadband supercontinuum generation in photonic crystal fibers using cosh-Gaussian optical pulses, which provide flatter spectrum than standard Gaussian pulses. This fact can be crucial for telecommunication systems applications. The intensive numerical study of three main telecommunication windows pointed out the most prominent window for spectral broadening. This finding offers the possibility of improving the characteristics of multi-wavelength sources and to enable wavelength density multiplexing systems.

Tunable microwave generation method based on birefringence photonic crystal fiber

A new method is proposed to generate tunable microwave by using single-light source and birefringence photonic crystal fiber (PCF), which is based on the interaction and the coupling between the two polarizations of the initial Gaussian optical pulse in PCF. A full vector finite element is used to design a high birefringence PCF. The expressions of the microwave are derived by couple-mode theory. The proof of concept device consists of a light source, a birefringence PCF, a polarizer controller and a photodetector. The frequency of the generated pulses can be controlled by adjusting the parameters of the optical fiber system. The simulation results demonstrate the system can generate the frequency of microwave are 8.03–37.67GHz and 26.82–125.5GHz from two kinds of PCFs, respectively. The system is elastic, stable, brief and highly efficient.

Self-phase modulation dominated supercontinuum generation employing cosh-Gaussian pulses in photonic crystal fibers

This paper presents an investigation of broadband supercontinuum (SC) generation in photonic crystal fibers using cosh-Gaussian optical pulses. It is found that the SC spectra of these cosh-Gaussian pulses are composed of several internal oscillations. The number of the oscillations increases with an increase in the value of the cosh parameter Ω0. The internal structure of the SC spectra shows an asymmetric behavior, possessing fewer oscillations as we move from the lower to higher wavelength region. Our results indicate that the SC generation dynamics is dominated by self-phase modulation.

Generation of stable two-color laser pulses in photonic crystal fiber for microscopy

We have generated two-color laser pulses in the visible range from a photonic crystal fiber pumped with a femtosecond Ti:sapphire oscillator. The central wavelengths of the two peaks are 564 and 644 nm with the tunable range of about 10 nm by adjusting the pump intensity. The average power of each peak is higher than 1 mW and the rms stability is 1.3%, which is nearly the same as the pump laser. The most probable mechanism of the formation of the two-color pulses is high-order soliton fission. The two-color femtosecond pulses are useful in microscopy.

Transverse propagation of ultraviolet and infrared femtosecond laser pulses in photonic crystal fibers

Transverse propagation of ultraviolet and infrared femtosecond laser pulses in photonic crystal fibers

Ultrabroadband SCG with quasi-continuous wave nanosecond-long pump pulses in PCF

An ultrabroadband supercontinuum (SC) is demonstrated in a pure silica photonic crystal fiber (PCF) pumped by quasi-continuous wave nanosecond-long pulses at 1,064 nm. The generated SC spectra extending from 450 to at least 2,400 nm have the salient feature of a short wavelength regime below the pump wavelength, which is much higher in intensity than the long-wavelength over the pump wavelength. The influence of pump power and repetition rates on SC generation (SCG) is explored. Results suggest that this pump source has both the advantages of short-pulse and continuous-wave pumps for SCG.

Modeling of four-wave mixing and supercontinuum with long pulses in photonic crystal fibers

We numerically investigated four-wave mixing (FWM) and supercontinuum generation in photonic crystal fibers (PCFs) in the long pump pulse scheme for the first time. We showed that simply based on phase-matching condition and energy conservation with quasi-continuous-wave approximation, one can theoretically determine the FWM signal and idler wavelengths with pump in the normal-dispersion regime, and the two symmetrical modulation instability sidebands with pump in the anomalous-dispersion regime. Using adaptive split-step Fourier method, we quantitatively simulated FWM and supercontinuum generation in PCFs with different dispersion profiles when pumping with a 1064 nm sub-nanosecond laser. Our simulation results agree with the experimental results very well.

Efficient Pulse Compression Using Tapered Photonic Crystal Fiber at 850 nm

By using appropriate self-similar scaling analysis, we delineate the generation of linearly chirped solitary pulses in photonic crystal fiber (PCF) at 850 nm to obtain the short pulses with large compression factor and minimal pedestal energy when compared to adiabatic compression scheme. The dispersion and nonlinearity varying nonlinear Schrödinger equation aptly models the pulse propagation in such a PCF. The analytical results demand that the effective dispersion must decrease exponentially while the nonlinearity must increase exponentially in the PCF. Thus, based on the analytical results, we propose the new design of tapered PCF by varying the pitch and diameter of the air hole. We adopt the projection operator method to derive the pulse parameter equations which indeed very clearly describe the self-similar pulse compression process at different parts of the PCF structures. As we are interested in constructing compact compressor, we also introduce another designing of PCF by filling chloroform in the core region. The chloroform filled tapered PCF exhibits low dispersion length for efficient pulse compression with low input pulse energy over small propagation distances.

Effects of the cross-phase modulation on the propagation of femtosecond optical pulses in photonic crystal fibers

The propagation of two femtosecond pulses in the region with minimum group-velocity dispersion, influenced by the cross-phase modulation (XPM) in photonic crystal fiber (PCF), is investigated in this paper. The adaptive split-step Fourier method is used to simulate the generalized nonlinear Schrodinger equations (GNSE). The numerical results show that the combination of the Raman scattering and XPM can make the spectrum and the pulse shape changed, inducing the pulse compression and supercontinuum generation. The Raman effect from molecular vibrations, which can make the pulse spectrum in anomalous-dispersion region to be more symmetrical, is also discussed.

Solitons evolving toward few-and single-cycle pulses in photonic-crystal fibers

Numerical analysis of soliton dynamics in highly nonlinear photonic-crystal fibers reveals intriguing scenarios enabling efficient pulse compression down to single-cycle field waveforms. We derive simple analytical expressions relating the pulse width and the energy of ultrashort pulses generated through such a field-evolution dynamics to the fiber dispersion and nonlinearity.

Pulse-shaping control of spectral transformations of ultrashort pulses in photonic-crystal fibers

We experimentally demonstrate that the initial pulse width and spectral phase of ultrashort laser pulses may significantly influence the solition dynamics of such pulses in a photonic-crystal fiber. These findings suggest new solutions for the transmission, shaping, stretching, amplification, and spectral transformation of ultrashort pulses in all-fiber laser technologies.

Nonlinear-optical spectral transformation of few-cycle laser pulses in photonic-crystal fibers

Photonic-crystal fibers with special dispersion profiles are shown to provide a high efficiency of spectral transformation of chirped sub-6-fs Ti:sapphire laser pulses. With the wavelength of zero group-velocity dispersion of the fiber lying within the broad spectrum of the input few-cycle pulse, the output spectra feature well-resolved spectral peaks, indicative of soliton self-frequency shift, four-wave mixing, and Cherenkov emission of dispersive waves. We demonstrate that up to 3% of radiation energy at the output of the fiber can be confined within a spectrally isolated soliton peak centered at , which is ideally suited as a seed for Nd:YAG- and ytterbium-based laser devices.

Soliton self-frequency shift of 6-fs pulses in photonic-crystal fibers

Raman soliton phenomena in photonic crystal fibers are shown to allow efficient tunable frequency shifting of sub-10-fs laser pulses. Soliton self-frequency shift in a photonic-crystal fiber with a core diameter less than 2 μm is used to transform the spectrum of a 6-fs 2-nJ Ti: sapphire-laser pulse, dominated by a 670-nm peak, into a spectrum featuring a well-resolved intense spectral component centered at 1064 nm, which is ideally suited as a seed for Nd: YAG- and ytterbium-based laser devices.