拉曼增益对双折射光纤中孤子传输特性的影响

本文采用考虑拉曼增益的耦合非线性薛定谔方程,利用分步傅里叶方法求解并仿真模拟了光孤子脉冲在不同性质的双折射光纤中传输时的演化过程.结果表明,拉曼增益可以有效抑制非线性耦合导致的孤子漂移,同时会导致光孤子脉冲峰值在传输时不断增大,产生拉曼放大效应.拉曼增益也可以有效抑制双折射光纤中传输的相邻光孤子之间的相互作用.     

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.     

Sequential generation of self-starting diverse operations in all-fiber laser based on thulium-doped fiber saturable absorber

Self-starting Q-switching, Q-switched mode-locking and mode-locking operation modes are achieved sequentially in an all-fiber erbium-doped fiber laser with thulium-doped fiber saturable absorber for the first time. The central wavelengths of Q-switching, Q-switched mode-locking and mode-locking operation modes are 1569.7 nm, 1570.9 nm, and 1572 nm, respectively. The mode-locking operation of the proposed fiber laser generates stable dark soliton with a repetition rate of 0.99 MHz and signal-to-noise ratio of 65 dB. The results validate the capability of generating soliton pulse by doped fiber saturable absorber. Furthermore, the proposed fiber laser is beneficial to the applications of optical communication and signal processing system.     

Experimental Observation of Bright and Dark Solitons Mode-Locked with Zirconia-Based Erbium-Doped Fiber Laser

We demonstrate the generation of dark and bright solitons with our homemade zirconia-based erbium-doped fiber and graphene oxide(GO) saturable absorber in anomalous dispersion region.The GO is fabricated using an abridged Hummer's method,which is combined with polyethylene oxide to produce a composite film.The film is sandwiched between two optical ferrules and embedded in the laser cavity to enhance its birefringence and nonlinearity.The self-starting bright soliton is easily generated at pump power of 78 mW with the whole length cavity of 14.7 m.The laser produces the bright pulse train with repetition rate,pulse width,pulse energy and central wavelength being 13.9 MHz,0.6 ps,2.74 p J and 1577.46 nm,respectively.Then,by adding the 10 m of single mode fiber into the laser cavity,dark soliton pulse is produced.For the formation of dark pulse train,the measured repetition rate,pulse width,pulse energy and central wavelength are 8.3 MHz,20 ns and 4.98 p J and1596.82 nm,respectively.Both pulses operate in the anomalous region.     

随机双折射对光孤子传输影响的研究

利用对称分步傅里叶法,数值模拟了光孤子在双折射光纤中的传输特性,分析了孤子脉冲两正交偏振分量的群速度失配对孤子传输产生的影响.结果表明,当光纤的双折射较小时,两偏振分量的脉冲强度变化不大,孤子基本能够保形传输|当光纤的双折射较大时,两偏振分量脉冲很快展宽,强度迅速减小,孤子不能够保形传输|如果光纤的双折射具有随机性,孤子传输的两偏振分量脉冲强度会随着传输距离有强弱不规则的变化,但是两偏振分量的强度变化互相补充,合成强度没有太大的变化,孤子能够稳定的传输|孤子间没有相互作用影响的传输距离随着光纤随机双折射偏振分量群速失配的增大而变小|通过选择恰当的振幅比,传统的不等振幅法仍然能够有效地抑制孤子间的相互作用.     

Influence of Randomly Varying Birefringence on Soliton Switching

In this paper, the effects of the randomly varying birefringence on soliton switching in the twin-core fiber are discussed through a nonlinear coupling equation , some novel and useful results on soliton switching are obtained.     

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.     

Soliton Propagation near Zero-Dispersion Wavelength in Birefringence Fiber

fiom coupled nonlinear Schrodinger equation which describes the birefringence near zero-dispersion wavelength, we derive the evolution feature of soliton parameters and get the differential equation describing the evolution of interval between solitons along with propagation distance. At the same time, we have made detailed numerical research on the propagation in dissipation system of standard fundamental soliton. The result shows that for attractive potential, the distance of oscillation increases dong with the loss increases. For repulsive potential, the distance of oscillation diverges faster along with the loss increases. If selecting the proper-optical fiber of high-order dispersion, the interaction between solitons in birefringence fiber can be eliminated.     

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.     

Dissipative dispersion-managed soliton 2 μm thulium/holmium fiber laser

We report a first dissipative dispersive-managed soliton fiber laser operating at 2?μm. The cavity comprised of all-anomalous-dispersion fiber employs chirped fiber Bragg grating, which ensures net-normal cavity dispersion and semiconductor saturable absorber for mode-locking.     

全正色散多波长被动锁模耗散孤子掺镱光纤激光器

报道了一种带有周期性双折射光纤滤波器的全正色散多波长被动锁模耗散孤子掺镱光纤激光器. 通过数值模拟发现加入滤波器后激光器能输出多波长耗散孤子脉冲, 调节滤波器带宽大小可以得到不同波长个数和波长间隔的多波长锁模耗散孤子脉冲. 在激光器产生的四波长和五波长耗散孤子脉冲中观察到了耗散孤子分子, 并且通过调节滤波器参数和饱和功率可以改变多波长脉冲中耗散孤子分子的个数和波长. 这是在被动锁模光纤激光器中首次实现包含有耗散孤子分子的多波长脉冲. 另外还在实验上实现了全正色散双波长被动锁模耗散孤子的产生. 关键词： 全正色散 耗散孤子 多波长脉冲 孤子分子     

Controllable dissipative soliton and Q-switched pulse emission in a normal dispersion fiber laser using SESAM and cavity loss tuning mechanism

We report on the controllable generation of the dissipative soliton and the Q-switched pulse in a normal dispersion fiber ring laser. The hybrid saturable absorber is used to obtain the dissipative soliton or the Q-switched pulse by slightly adjusting the polarization controller. Based on the experimental results and theoretical analysis, the controllable dissipative soliton and Q-switched pulse emission can be induced by the cavity loss tuning mechanism of the fiber laser.     

双折射光纤中非线性耦合Schr?dinger方程的小振幅孤波解

采用小振幅孤波近似法，得到非线性耦合Schr?dinger方程决定的双折射光纤中的小振幅孤波解，它们可以同时存在于正常色散区或者分别处于正常和反常色散区． 关键词：     

Time Jitters Caused by Randomly Varying Birefringence in Soliton Transmission System

Soliton propagation in fiber with randomly varying birefringence is studied by using self-companying operator method. It is shown that randomly varying birefringence leads to time jitters increasing with transmission distance, and disrupts the stability of soliton transmission. The fluctuation of time jitters is stochastic, and nonlinear gain is introduced to remove the influence.     

All-fiber erbium-doped dissipative soliton laser with multimode interference based on saturable-reserve saturable hybrid optical switch

Reverse saturable absorption is essential for the realization of dissipative solitons. In this paper, we introduce reverse saturable absorption by using nonlinear multimode interference (NL-MMI), for the first time, to the best of our knowledge, and obtain a stable dissipative soliton operation. By adjusting the coupling efficiency from multimode fiber to single mode fiber, the absorption properties of NL-MMI can be switched between saturation and reverse saturation. The dissipative soliton can be obtained with pulse width of 975 fs in the experiment, the 3-dB bandwidth at 1555 nm is 16 nm, and the maximum output power is 11.48 mW. The nonlinear absorption optical modulation and high damage threshold characteristics of the NL-MMI based ultrafast optical switch provide a new idea for realizing dissipative solitons.     

Artificial spectral filtering in dissipative soliton fiber lasers with invisible bandpass filters

We numerically study the artificial spectral-filtering effect in dissipative soliton fiber lasers without intracavity spectral filters. It is found that in dissipative soliton lasers with real saturable absorbers (SAs), the dynamic spectral filtering of the real SAs serves as an artificial spectral filter and contributes to the pulse shaping. While in the dissi- pative soliton lasers with artificial SAs, such as nonlinear polarization rotation, the spectral filtering introduced by the intracavity polarization-dependent components acts as an artificial spectral filter and shapes the pulses to obtain mode-locking. An investigation of the artificial spectral-filtering effect reveals the operating mechanisms of the dissipative soliton fiber lasers without visible bandpass filters.     

Nonlinear tunneling of optical soliton in 3 coupled NLS equation with symbolic computation

We investigated the soliton solution for N$N$ coupled nonlinear Schrödinger (CNLS) equations. These equations are coupled due to the cross-phase-modulation (CPM). Lax pair of this system is obtained via the Ablowitz–Kaup–Newell–Segur (AKNS) scheme and the corresponding Darboux transformation is constructed to derive the soliton solution. One and two soliton solutions are generated. Using two soliton solutions of 3 CNLS equation, nonlinear tunneling of soliton for both with and without exponential background has been discussed. Finally cascade compression of optical soliton through multi-nonlinear barrier has been discussed. The obtained results may have promising applications in all-optical devices based on optical solitons, study of soliton propagation in birefringence fiber systems and optical soliton with distributed dispersion and nonlinearity management.     

Toward higher-order passive harmonic mode-locking of a soliton fiber laser

We report >13 MHz/mW pump power efficiency in increasing the repetition rate of passive harmonic mode-locking by engineering the soliton pulse energy in Er fiber lasers incorporating carbon nanotube saturable absorber. Stable pulses with a ～5 GHz repetition rate and 40 dB of super-mode suppression are demonstrated with only ～400 mW pump power in a single-clad fiber laser.     

Observation of soliton bound states in a graphene mode locked erbium-doped fiber laser

We report on the experimental observation of bound states of solitons in a graphene mode locked erbium-doped fiber laser. By using graphene as a saturable absorber, we have obtained stable, single and bound soliton pulses, the latter with a full width at half maximum (FWHM) of 1.49 ps and a fixed pulse separation of 2.46 ps. Our results once again show that bound soliton pulses is an intrinsic feature of fiber lasers independent of the exact mode locking mechanism.     

Bound states of solitons in a fiber laser mode locked with carbon nanotube saturable absorber

We report on the experimental observation of bound states of solitons in an erbium-doped fiber laser passively mode-locked by the carbon nanotube saturable absorber. Bound states of solitons with various pulse separations are obtained. While the tightly bound solitons always exhibit the same set of fixed discrete pulse separations with π or π/2 phase difference, the feature becomes less obvious for the loosely bound solitons. The result that various states of the bound solitons were obtained in the same fiber laser makes a systematic experimental study on them and a comparison of their properties possible. Our results once again show that the bound soliton emission is an intrinsic feature of the mode-locked soliton fiber lasers.