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1.
尹经禅  肖晓晟  杨昌喜 《物理学报》2009,58(12):8316-8325
为了避免在高功率光纤放大器和光纤相位共轭镜等实际应用中因受激Brillouin散射(SBS)造成的光纤损伤,根据描述SBS动态弛豫振荡特性的振幅耦合方程,利用有限差分的数值模拟方法研究了光纤中SBS的动态弛豫振荡特性,并对其抑制进行了初步探讨.得到了光纤中SBS弛豫振荡在不同的脉冲上升时间的时空三维图;同时利用方波和脉冲光作抽运光进行了相应实验研究,实验结果与理论模拟结果符合很好.结果表明,增大抽运光脉冲上升时间可以有效抑制因SBS而产生的弛豫振荡,进而避免因其造成的光纤损伤. 关键词: 受激Brillouin散射 动态弛豫振荡特性 有限差分法  相似文献   
2.
孔令杰  肖晓晟  杨昌喜 《中国物理 B》2011,20(2):24207-024207
Passive harmonic mode-locking of dissipative solitons is demonstrated in all-normal dispersion Yb-doped fibre lasers.A difference equation model of the mode-locked fibre lasers is adopted to simulate the intra-cavity nonlinear dynamics.Hysteresis phenomena around the mode-locking threshold,and the effect of introducing linear phase bias are discussed.The passive harmonic mode-locking as one kind of multipulsing operations is revealed.Moreover,the simulation shows the bistability between multipulsing and single-pulse or period multiplication.  相似文献   
3.
Polarization dependent loss (PDL) has been recognized as a critical issue because various inline optical components may have nonnegligible PDL effect that interacts with polarization mode dispersion (PMD). We investigated the impact of PMD-PDL interaction on degree of polarization (DOP), which is the most commonly used feedback signal in PMD compensation. The simulation results of a 40-Gb/s NRZ code optical transmission system show that the maximum PMD increases from approximately 40 ps to more than 45 ps, while minimum DOP declines from approximately 0.6 to approximately 0.2. The interaction of PMD and PDL also induces residual PMD underestimation of 5-8 ps, which causes degradation of PMD compensation performance.  相似文献   
4.
Polarization mode dispersion (PMD) is becoming major system impairment in high speed and long distance opti- cal fiber transmission systems. Since the PMD-induced pulse spreading is a frequency-dependent statistic pa- rameter and varies randomly over time, it is difficult to be compensated[1-3]. Large length of single mode opti- cal fiber is needed to generate certain amount of PMD in laboratory, and the PMD effect in the fiber varies slightly and slowly over time. Therefore, PMD emula- …  相似文献   
5.
输出波长在560~590nm的全固态拉曼黄光激光器是近几年兴起的激光器之一。目前,此类激光器内部多模振荡引起的黄光输出谱线单色性较差的问题还没有得到解决。针对这一情况,提出将扭转模腔与拉曼复合腔相结合的新型解决方案,从根本上消除增益介质中空间烧孔效应引起的基频光多模振荡,实现单纵模黄光输出。拉曼复合腔由L型基频光谐振腔与直线型拉曼谐振腔耦合而成,既保证各个非线性变换过程可充分利用腔内的高功率密度,又可相对独立地对不同波长的光路进行优化调节,从而使整个系统实现最佳输出。该设计有助于在全固态拉曼激光器中实现毫瓦量级的单纵模黄光输出,为基于黄激光的生物医疗、钠导星、空间目标识别等系统提供理想的固体黄光光源。  相似文献   
6.
孔令杰  肖晓晟  杨昌喜 《中国物理 B》2012,21(9):94210-094210
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.  相似文献   
7.
尹经禅  肖晓晟  杨昌喜 《物理学报》2010,59(6):3986-3991
对基于光纤四波混频(FWM)波长转换和色散的慢光实现进行了详细和系统的实验研究.首先,实验测定了高非线性光纤中FWM带宽约为40 nm,从而确定了慢光的可调谐带宽;接着,在普通单模光纤和色散补偿光纤(DCF)中针对500 MHz正弦信号和100 ps短脉冲信号分别实现了34和198 ns的脉冲延迟,在DCF中还实现了209 ns的脉冲提前.讨论了增大延迟量的方法,指出随着宽带FWM波长转换的实现和大色散光纤的应用有望获得微秒量级的大延迟量,从而为高性能光纤延迟线和全光缓存器等应用提供支持. 关键词: 慢光 四波混频 色散  相似文献   
8.
一种新型高非线性色散平坦光子晶体光纤结构   总被引:12,自引:0,他引:12  
刘洁  杨昌喜  Claire Gu  金国藩 《光学学报》2006,26(10):569-1574
提出了一种新的高非线性色散平坦光子晶体光纤结构,引入了一个衡量非线性和色散平坦的品质因子δ。采用平面波展开法,研究了气孔尺寸对光子晶体光纤色散特性和非线性的影响。新结构在第一圈空气孔的中间插入六个附加小孔,使得光子晶体光纤有更小的有效模场面积,提高了光纤的非线性。通过控制第一圈和第三圈空气孔以及附加小孔的直径,使得该光子晶体光纤在大约330 nm的波长范围内,光纤的色散系数介于±0.5 ps/(km.nm)之间,在大约230nm的波长范围内,光纤的色散系数介于±0.1 ps/(km.nm)之间,在大约200 nm的波长范围内,光纤的色散系数D的值介于±0.05 ps/(km.nm)之间。光纤的有效模场面积为2.26μm2。衡量非线性和色散平坦的品质因子δ=11.8 ps.W/μm2。  相似文献   
9.
张林  杨昌喜 《中国物理快报》2003,20(8):1293-1295
A sinusoidal chirp structure is proposed to improve the performance of fibre gratings as dispersion compensators and multichannel filters. Nearly ideal reflection spectra from sinusoidally chirped fibre gratings are exhibited. The bandwidth utilization defined as the ratio of-1 dB to -30 dB bandwidths could be higher than 0.85, even up to 0.985. The sinusoidal chirp can be applied to the sampled fibre gratings to enhance channel uniformity. We demonstrate 141 uniform channels with a 25-GHz spacing for high dense wavelength multiplexing applications.  相似文献   
10.
We report the frequency dependence of polarization mode dispersion (PMD) in a PMD compensator based on six cascaded birefringent crystals separated by Faraday rotators. When all crystal axes are aligned, the device can compensate for the first-order PMD. However, if all crystal axes are coupled with arbitrary angles, it can compensate for high-order PMD. The variations of differential group delay and principal state of polarization with optical frequency are analysed. The PMD vector and Stokes components of the device versus wavelength are measured. The theoretical simulations agree well with the experimental results.  相似文献   
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