Dispersion-decreasing Fiber Research Articles

Self-similar pulse evolution in a fiber laser with a comb-like dispersion-decreasing fiber.

We demonstrate an erbium fiber laser with self-similar pulse evolution inside a comb-like dispersion-decreasing fiber. We show numerically and experimentally that the comb-like dispersion-decreasing fiber works as well as an ideal one, and offers major practical advantages. The existence of a nonlinear attractor is verified by the invariant pulse chirp over a wide range of net cavity dispersion in experiments. The laser generates 1.3 nJ pulses with parabolic shapes and linear chirps, which can be dechirped to 37 fs. Comb-like dispersion-decreasing fiber should enable the generation of high-energy few-cycle pulses directly from a fiber oscillator.

Influence of gain coefficient on the self-similar pulses propagation in a dispersion-decreasing fiber

This paper first investigates the influence of the dispersion-decreasing optical fiber structure on the self-similar pulses interaction and compression. The dynamic of the evolution of a pair of self-similar pulses in a dispersion-decreasing optical fiber with normal group-velocity dispersion (ND-DDF) under different gain coefficient g0 of DDF is analyzed, and the chirp evolution is also studied to analyze the propagation characteristic of self-similar pulses. The numerical simulations show that the change of gain coefficient g0 of DDF can impact directly on the linear chirp of the self-similar pulses. We find out that the smaller g0 can generate better high-quality femto-second pulses than the higher g0 after pulses compression. Finally, we got a pair of ultra-short pulses with a FWHM of 124fs at g0=0.015m−1, indicating efficient and high-quality pulse compression.

Akhmediev breathers, Kuznetsov–Ma solitons and rogue waves in a dispersion varying optical fiber

Dispersion varying fibres have applications in optical pulse compression techniques. We investigate Akhmediev breathers, Kuznetsov–Ma (KM) solitons and optical rogue waves in a dispersion varying optical fibre based on a variable-coefficient nonlinear Schrödinger equation. Analytical solutions in the forms of Akhmediev breathers, KM solitons and rogue waves up to the second order of that equation are obtained via the generalised Darboux transformation and integrable constraint. The properties of Akhmediev breathers, KM solitons and rogue waves in a dispersion varying optical fibre, e.g. dispersion decreasing fibre (DDF) or a periodically distributed system (PDS), are discussed: in a DDF we observe the compression behaviours of KM solitons and rogue waves on a monotonically increasing background. The amplitude of each peak of the KM soliton increases, while the width of each peak of the KM soliton gradually decreases along the propagation distance; in a PDS, the amplitude of each peak of the KM soliton varies periodically along the propagation distance on a periodic background. Different from the KM soliton, the Akhmediev breather and rogue waves repeat their behaviours along the propagation distance without the compression.

色散平坦渐减光纤中非线性啁啾脉冲的传输及超连续谱的产生

色散平坦渐减光纤中非线性啁啾脉冲的传输及超连续谱的产生

非线性色散渐减光纤中高峰值脉冲的激发和传输

非线性色散渐减光纤中高峰值脉冲的激发和传输

Ultrafast fiber lasers based on self-similar pulse evolution: a review of current progress

Self-similar fiber oscillators are a relatively new class of mode-locked lasers. In these lasers, the self-similar evolution of a chirped parabolic pulse in normally-dispersive passive, active, or dispersion-decreasing fiber (DDF) is critical. In active (gain) fiber and DDF, the novel role of local nonlinear attraction makes the oscillators fundamentally different from any mode-locked lasers considered previously. In order to reconcile the spectral and temporal expansion of a pulse in the self-similar segment with the self-consistency required by a laser cavity’s periodic boundary condition, several techniques have been applied. The result is a diverse range of fiber oscillators which demonstrate the exciting new design possibilities based on the self-similar model. Here, we review recent progress on self-similar oscillators both in passive and active fiber, and extensions of self-similar evolution for surpassing the limits of rare-earth gain media. We discuss some key remaining research questions and important future directions. Self-similar oscillators are capable of exceptional performance among ultrashort pulsed fiber lasers, and may be of key interest in the development of future ultrashort pulsed fiber lasers for medical imaging applications, as well as for low-noise fiber-based frequency combs. Their uniqueness among mode-locked lasers motivates study into their properties and behaviors and raises questions about how to understand mode-locked lasers more generally.

Generation of a broad IR spectrum and -soliton compression in a longitudinally inhomogeneous dispersion-shifted fibre

The propagation of -soliton pulses in an optical fibre with slowly decreasing, shifted anomalous dispersion has been studied experimentally and theoretically. Using a generalised nonlinear Schrödinger equation, we have constructed an adequate numerical model for light propagation in such fibre. Using numerical simulation, we have shown that the use of dispersion-decreasing fibres ensures higher average dispersive radiation intensity and better uniformity of the supercontinuum spectrum. A reduction in the third-order dispersion of such fibres enables supercontinuum generation with a bandwidth exceeding that in homogeneous fibres by several hundred nanometres even in the case of a medium-power subpicosecond source.

Analysis and design of supercontinuum pulse generation in a single-mode optical fiber: erratum

We present an analysis and describe the design of supercontinuum (SC) pulse generation in a single-mode optical fiber. SC generation with a dispersion-decreasing fiber with a convex dispersion profile is contrasted with other approaches to obtaining conditions for generating a flat, broadened spectrum. We present general criteria for SC generation by introducing normalized parameters that allow the shape of the SC spectrum to be invariant for several SC-generating fibers and optical pump pulses. Based on these results, we designed a SC fiber and experimentally generated SC pulses that were in good agreement with theory.

Dynamics of self-similar pulse generated in normal dispersion-decreasing fiber

Self-similar pulse can be generated in a normal dispersion-decreasing fiber. We show that the dynamics of self-similar pulse evolution is governed by the different spectrum broadening mechanisms in the different stages, which is confirmed by the typical pulse spectral structures with amplitude noise added.

Investigation on nonautonomous soliton management in generalized external potentials via dispersion and nonlinearity

We investigate the controllable behavior of nonautonomous soliton in external potentials with variable dispersion and nonlinearity management functions, which describes the propagation of optical pulses in an inhomogeneous fiber system. We derive the Lax pair with a variable spectral parameter and the exact multi-soliton solution is generated via Darboux transformation. Based on these solutions, several novel optical solitons are constructed by selecting appropriate functions and the main evolution features of these waves are shown by some interesting figures with computer simulation. As few examples, breathers in periodic potential, soliton compression in an exponentially dispersion decreasing fiber and interaction of boomerang solitons are discussed. The presented results have applications in the study of nonautonomous soliton birefringence-managed switching architecture. These results are potentially useful in the management of nonautonomous soliton with external potentials in the optical soliton communications and long-haul telecommunication networks.

色散平坦渐减光纤中抽运残余成分的抑制与平坦超连续谱的产生

色散平坦渐减光纤中抽运残余成分的抑制与平坦超连续谱的产生

All-fiber dual wavelength passive Q-switched fiber laser using a dispersion-decreasing taper fiber in a nonlinear loop mirror.

This paper describes a proposal and successful demonstration of a dual wavelength all-fiber passively Q-switched erbium-doped fiber ring laser. The Q-switch operation was realized by using a nonlinear loop mirror that incorporated an unbalanced dispersion-decreasing taper fiber to act as a saturable absorber without additional elements. This setup enabled a fiber ring laser to achieve a performance of 48.7 kHz repetition rate with pulse duration of around 3.2 μs and approximate pulse energy of 20 nJ.

Compression characteristics and parameter optimization of a passive self-similar compressor based on dispersion-decreasing fiber

The compression characteristics of a passive self-similar compressor consisting of a dispersion- decreasing fiber (DDF) and a compensative fiber are numerically investigated. The results show that the group-velocity dispersion (GVD) of the compensative fiber has a periodic influence on the compression factor and peak power of the compressed pulse. That is, the pulse energy is concentrated, then dispersed, and then concentrated again periodically. Every time the energy is concentrated, the pulse width reaches its compression limit. With the increase of the GVD value of the compensative fiber, the period interval increases and more energy is transferred within a period. On the other hand, an increase of the nonlinearity of the compensative fiber leads to a decrease of the compression factor, which is not conducive to pulse compression. Moreover, the degree of self-similar evolution is decided by the length of the DDF. A suitable evolution degree and optimal DDF length cause the pulse to reach a maximum compression limit. In addition, the optimal compensative fiber length increases with the degree of self-similar evolution and decreases with the GVD value of the compensative fiber, although it has nothing to do with the nonlinearity of the compensative fiber. By optimizing the parameters of the compensative fiber and the length of the DDF, the pulse width attains a compression limit and a high-quality pulse is obtained. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of

On the amplification of unchirped soliton pulses in a dispersion-decreasing fiber

In this paper, based on a variable-coefficient nonlinear Schrodinger (vcNLS) equation, amplification of the fundamental and second-order unchirped solitons in the dispersion-decreasing fiber without any external amplification device, which is different from those in the existing literatures, is studied. Via symbolic computation, soliton solutions of the vcNLS equation are obtained. For a fundamental-soliton pulse, the amplitude is amplified by the gain during the propagation, whereas the width keeps unchanged. Because of the equilibrium between the gain, nonlinearity and varying dispersion, soliton structure is not destroyed, and the amplified fundamental soliton is free from the pedestal and chirp. With the increase of the absolute value of the gain coefficient $$\alpha $$ , magnification of the fundamental-soliton amplitude is enhanced in the same propagation distance. For the second-order soliton, the width is compressed and the amplitude is amplified, because the amplification process is accompanied by the compression of the soliton. Period of the second-order soliton decreases exponentially during the propagation, and decreases with the increase of the absolute value of $$\alpha $$ in the same propagation distance.

Soliton interactions in dispersion-decreasing fibers with the exponential dispersion profile

In this paper, soliton interactions in dispersion-decreasing fibers with the exponential dispersion profile will be investigated. Analytic two-soliton solutions will be obtained with Hirota’s method. With the different dispersion profile of dispersion-decreasing fibers, the propagation characteristics of solitons will be exhibited, and some soliton properties will be adjusted. Results presented in this paper could be used in soliton control in the dispersion-decreasing fibers.

Ideal optical backpropagation of scalar NLSE using dispersion-decreasing fibers for WDM transmission

An ideal optical backpropagation (OBP) scheme to compensate for dispersion and nonlinear effects of the transmission fibers is proposed. The scheme consists of an optical phase conjugator (OPC), N spans of dispersion-decreasing fibers (DDFs) and amplifiers, placed at the end of the fiber optic link. In order to compensate for the nonlinear effects of the transmission fibers exactly, the nonlinear coefficient of the backpropagation fiber has to increase exponentially with distance or equivalently the power in the backpropagation fiber should increase exponentially with distance if the nonlinear coefficient is constant. In this paper, it is shown that a combination of DDFs and amplifiers can compensate for the nonlinear effects exactly. An analytical expression for the dispersion profile of the DDF is derived. Numerical simulation of a long haul wavelength division multiplexing (WDM) fiber optic system with the proposed OBP scheme shows that the system reach can be enhanced by 54% as compared to digital backpropagation (DBP).

Modulation instability induced by cross-phase modulation in dispersion-decreasing fiber with high-order dispersion and high-order nonlinearity

The modulation instability (MI) induced by cross-phase modulation (XPM) in dispersion-decreasing fiber (DDF) is investigated based on extended nonlinear Schrödinger equations with high-order dispersion and high-order nonlinearity considered. The effects of fourth-order dispersion, quintic nonlinearity, dispersion decaying factor and different group velocity dispersion (GVD) on the gain spectra are analyzed. The results show that due to fourth-order dispersion, XPM occurs at two spectral regions in both the normal and the anomalous dispersion regimes of DDF. The positive (negative) quintic nonlinearity will make the width and the peak value of the gain spectra larger (smaller). The spectral width of XPM in DDF increases with increasing dispersion decaying factor. There are still two XPM regions in both the normal and anomalous dispersion regimes in DDF with different GVD.

Beat signal compression by loop mirror constructed with linear dispersion decreasing fiber

A nonlinear optical loop mirror (NOLM) constructed with linear dispersion decreasing fiber (DDF) is used to compress a beat signal. Several factors impacting on quality of output pulse in this compression system, such as dispersion slope of DDF, power-splitting ratio, incident pulse shape and peak power, are analyzed numerically. The new method for selecting device characteristics is adopted to enable both good pedestal suppression and pulse compression. As a result, the output pulse train with tunable and high repetition rate, pedestal energy of 5.09%, compression ratio of 25.6 and energy transmissivity of 50.56% is obtained by using 0.524 km-long DDF with dispersion slope of 26 ps2/km2 and a coupler with power-splitting ratio of 0.54.

Soliton solutions with power-law nonlinearity in inhomogeneous media

We construct the relation between the variable coefficient nonlinear Schrödinger equations with power-law nonlinearity and the constant coefficient one via a transformation. Based on this transformation, we analytically obtain the closed-form bright and dark soliton solutions for variable coefficient nonlinear Schrödinger equations with power-law nonlinearity, third-order dispersion and self-steepening effect. The dynamic behaviors of bright and dark solitons in dispersion-decreasing fibers with hyperbolic, exponential, linear, logarithmic and Gaussian profiles are analyzed.

Modulation instability induced by cross-phase modulation with the fourth-order dispersion in dispersion-decreasing fiber

The modulation instability (MI) induced by cross-phase modulation (XPM) in dispersion-decreasing fiber (DDF), whose dispersion decreases along the direction of propagation, is solved and analyzed by the perturbation method for the extended nonlinear Schr¨odinger equation, considering the higher-order dispersion. The change of the gain spectra with incident power and dispersion decaying factor are also given respectively. Due to the fourth-order dispersion, XPM occurs at two gain spectral regions in both the normal and the anomalous dispersion regimes of DDF. The two gain spectral regions in the anomalous dispersion regime are larger than those in the normal dispersion regime. Moreover, the gain spectrum of the second region in the anomalous dispersion regime is near zero compared with that in the normal dispersion regime, indicating that XPM can be easily produced in the anomalous dispersion regime. The spectral width increases with the increase of the incident optical power and the dispersion decaying factor.