Observation of antisymmetric dispersion-managed solitons in a mode-locked laser

We report experimental evidence of antisymmetric solitons in a mode-locked fiber laser with a strong dispersion map. A dispersion-managed soliton breathes as it traverses the dispersion map, and the antisymmetric dispersion-managed soliton can be considered a tightly bound soliton pair with pi phase difference between the component solitons. The antisymmetric soliton is observed only at particular values of the net cavity dispersion.     

Period-doubling of gain-guided solitons in fiber lasers of large net normal dispersion

We report on the experimental observation and numerical simulations of period-doubling of gain-guided solitons in an erbium-doped fiber laser operating in the large net normal cavity dispersion regime. Features of the solitons before and after the period-doubling bifurcation are studied. Our results suggest again that period-doubling is an intrinsic feature of the mode-locked soliton lasers, which is independent of the mode-locked pulse property.     

Vector dissipative solitons in graphene mode locked fiber lasers

Vector soliton operation of erbium-doped fiber lasers mode locked with atomic layer graphene was experimentally investigated. Either the polarization rotation or polarization locked vector dissipative solitons were experimentally obtained in a dispersion-managed cavity fiber laser with large net cavity dispersion, while in the anomalous dispersion cavity fiber laser, the phase locked nonlinear Schrödinger equation (NLSE) solitons and induced NLSE soliton were experimentally observed. The vector soliton operation of the fiber lasers unambiguously confirms the polarization insensitive saturable absorption of the atomic layer graphene when the light is incident perpendicular to its 2-dimentional (2D) atomic layer.     

Observation of dark pulse in a dispersion-managed fiber ring laser

The observation of dark pulse in a dispersion-managed fiber ring laser with net negative cavity group velocity dispersion (GVD) is reported. Both bright and dark pulses can be obtained in our fiber laser. When we appropriately adjust the cavity birefringence to achieve triple-wavelength mode-locked operation in the laser by rotating the polarization controller, the bright pulse could be switched to dark pulse. It is believed that the dark dispersion-managed (DM) pulse generation is caused by the linear and nonlinear intermodulation effects among the three wavelength pulses.     

Dynamics of gain-guided solitons in a dispersion-managed fiber laser with large normal cavity dispersion

The intra-cavity pulse dynamics of gain-guided solitons in a dispersion-managed fiber laser with large normal cavity dispersion was investigated experimentally and numerically. It was found that in the laser the gain-guided solitons have a similar evolution as that of the parabolic pulses.     

Power dependence of dispersion-managed solitons for anomalous, zero, and normal path-average dispersion

We determine the power dependence of dispersion-managed solitons on map strength and average dispersion, using a combination of numerical simulations and the variational approach. In particular, we investigate the behavior near zero dispersion and identify the region of existence of dispersion-managed solitons in the average normal-dispersion regime.     

Dark pulse generation in a dispersion-managed fiber laser

We report an experimental observation of dark pulse generation in a dispersion-managed erbium-doped fiber laser with net anomalous cavity group-velocity dispersion. It is found that apart from the bright soliton pulses, dark pulses with spectral sidebands could be obtained in the laser under appropriate operating conditions. The generation of dark pulses may be attributed to soliton shaping in the cavity.     

Variable-coefficient higher-order nonlinear Schrödinger model in optical fibers: Variable-coefficient bilinear form,Bäcklund transformation,brightons and symbolic computation

Symbolically investigated in this Letter is a variable-coefficient higher-order nonlinear Schrödinger (vcHNLS) model for ultrafast signal-routing, fiber laser systems and optical communication systems with distributed dispersion and nonlinearity management. Of physical and optical interests, with bilinear method extend, the vcHNLS model is transformed into a variable-coefficient bilinear form, and then an auto-Bäcklund transformation is constructed. Constraints on coefficient functions are analyzed. Potentially observable with future optical-fiber experiments, variable-coefficient brightons are illustrated. Relevant properties and features are discussed as well. Bäcklund transformation and other results of this Letter will be of certain value to the studies on inhomogeneous fiber media, core of dispersion-managed brightons, fiber amplifiers, laser systems and optical communication links with distributed dispersion and nonlinearity management.     

Period-doubling of multiple solitons in a passively mode-locked fiber laser

We report on the experimental observation of period-doubling of randomly distributed multiple solitons in a passively mode-locked fiber laser. We show that after a period-doubling bifurcation, the period of each soliton in the cavity becomes doubled. However, the intensity variation of the solitons is not necessarily synchronized, indicating that their period-doubling is unrelated. Numerical simulations verified the experimental observations.     

Soliton-like pulse-shaping mechanism in passively mode-locked surface-emitting semiconductor lasers

We discuss a mechanism that allows the formation of nearly transform-limited soliton-like pulses in passively mode-locked optically pumped external-cavity surface-emitting semiconductor lasers. It involves the interplay of positive dispersion and the nonlinear index changes in gain medium and saturable absorber, while ordinary solitons are based on dispersion and the Kerr effect. The obtained quasi-soliton pulses share some of the properties of ordinary solitons (in particular, their stability and near bandwidth-limited nature), while other properties are different. In particular, the pulse duration scales with the square root of the cavity dispersion, and an excessive drift of the laser wavelength must be avoided by proper design. Received: 23 April 2002 / Published online: 25 September 2002 RID="*" ID="*"Corresponding author. Fax: +41-1/633-1059, E-mail: Paschotta@iqe.phys.ethz.ch     

Gain-guided solitons in dispersion-managed fiber lasers with large net cavity dispersion

Gain-guided solitons are experimentally observed in dispersion-managed fiber lasers with large net positive group-velocity dispersion. It is shown that formation of the soliton is a robust feature of the lasers. Numerical simulations also confirmed the experimental results.     

Effect of group-delay ripples on dispersion-managed soliton communication systems with chirped fiber gratings

The effect of group-delay ripples in dispersion-managed soliton communication systems that use chirped fiber gratings for dispersion compensation is studied. Using both a reduced model and direct numerical simulation, we find that dispersion-managed solitons exist even in the presence of large dispersion variation caused by group-delay ripples. The dispersion-managed solitons suppress the growth of intersymbol interference induced by the group-delay ripples.     

基于高能量耗散型脉冲掺铒光纤激光器的实验研究

在正色散掺铒光纤激光器中,利用非线性偏振旋转技术实现自启动锁模,得到了具有极大光谱宽度的高能量、无波分裂耗散型脉冲.该耗散型脉冲的形成是腔内增益、损耗、非线性偏振旋转、正色散和其他非线性效应等共同作用的结果,其形成机理与传统的负色散激光器完全不同.当抽运功率为500mW时,该类型脉冲的光谱覆盖了1530—1660nm范围,半高全宽光谱宽度可达42nm以上.脉冲具有极大的正啁啾,其时间带宽积为483,而单脉冲总能量最大可达34.4nJ.     

Properties of a vector soliton laser passively mode-locked by a fiber-based semiconductor saturable absorber operating in transmission

We experimentally demonstrate a passively mode-locked fiber laser employing a fiber-based semiconductor saturable absorber (SSA) operating in transmission. Polarization rotation locked vector solitons are observed in the laser. Due to the intrinsic dynamic feature of the laser, period-doubling of these vector solitons has also been observed. Furthermore, extra spectral sidebands are formed on the optical spectrum, caused by the energy exchange between the two orthogonal polarization components of the vector solitons. By careful reduction of the pump power together with fine adjustment to the cavity birefringence, period-one state can further be obtained. Additionally, the phase noise properties of the vector soliton fiber laser have also been characterized experimentally and analytically.     

Diode-pumped Cr:LiCAF fs regenerative amplifier system seeded by an Er-doped mode-locked fiber laser

A fs regenerative amplifier based on Cr:LiCAF is demonstrated for the first time. With direct diode pumping, 8 μJ of pulse energy are obtained directly from the amplifier. When seeded by an Er-doped fiber laser, the amplified seed pulses are compressed down to 252 fs, limited by residual net third-order dispersion of the compression gratings and intracavity elements. Pulse broadening due to second- and third-order dispersion is theoretically investigated and compared to experimental results. Dispersion generated by the geometrical cavity arrangement is measured experimentally. Received: 19 November 2001 / Revised version: 28 January 2002 / Published online: 14 March 2002     

Dispersion management with filtering

We present analytical and numerical results for dispersion-managed solitons in a fiber link including guiding filters and compensating gain, both taken in the distributed approximation. Stationary propagation regimes with anomalous, zero, and normal path-average dispersion (PAD) are identified. New features, compared with those of the case without filters, are the absence of a critical strength for propagation at zero and normal PAD and, instead, the existence of a critical power for stationary propagation at any PAD.     

Induced solitons formed by cross-polarization coupling in a birefringent cavity fiber laser

We report on the experimental observation of induced solitons in a passively mode-locked fiber ring laser with a birefringence cavity. Owing to the cross coupling between the two orthogonal polarization components of the laser, it was found that if a soliton was formed along one cavity polarization axis, a weak soliton was also induced along the orthogonal polarization axis, and depending on the net cavity birefringence, the induced soliton could have either the same or different center wavelengths to that of the inducing soliton. Moreover, the induced soliton always had the same group velocity as that of the inducing soliton. They formed a vector soliton in the cavity. Numerical simulations confirmed the experimental observations.     

On the behaviour of dispersion-managed soliton from the perspective of its energy components

We investigate the behaviour of dispersion-managed (DM) soliton from its energy. Using the variational analysis, it is possible to represent the energy of the DM soliton as a combination of three components, respectively, one component for the average dispersion of the optical fiber, second component for the local dispersion of the dispersion map and the third component for the Hamiltonian of the anomalous fiber section. From the results of the numerical simulations, we show that the Hamiltonian component of the DM soliton energy plays a vital role in the determination of its stability.     

Period-doubling of vector solitons in a ring fiber laser

Period-doubling of vector solitons in a ring fiber laser was experimentally observed for the first time. Apart from period-doubling of single vector soliton, period-doubling of multiple vector solitons was observed as well. Numerical simulation verified the experimental observation.     

High-energy dissipative soliton with MHz repetition rate from an all-fiber passively mode-locked laser

We experimentally demonstrate pulse energy enhancement in an all-fiber passively mode-locked laser operating in the large normal dispersion regime. By increasing the laser cavity length as well as its net cavity dispersion, the proposed laser, which is mode-locked by nonlinear polarization rotation, generates highly chirped dissipative solitons with pulse energies up to 9.4 nJ. The fundamental repetition rate is 2.3 MHz, and the pulse duration is 35 ps. Such low repetition rate as well as wide pulse width makes this mode-locked all-fiber laser a suitable oscillator to directly seed a fiber amplifier, which can be used as compact sources for high-power applications.