共查询到20条相似文献,搜索用时 0 毫秒
1.
The system performances in second- and third-order polarization mode dispersion (PMD) compensations have been calculated analytically and a proper approach for the higher order PMD compensation has been investigated. The investigation has revealed that the frequency averaged higher order terms of the fiber link's PMD vector should be used as the coefficient vectors in emulating the frequency dependent compensation vector for higher order PMD compensation. 相似文献
2.
A formulation of ray optics that takes the polarisation of electromagnetic waves into account shows that the maximum difference in time delay between corresponding HE and EH modes is, for almost any multimode graded-index fibre, of the order of 10 000 (?n/n)2/V ns/km, where V is the V-number of the fibre and ?n is the variation of the refractive index between axis and cladding. The effect of polarisation on pulse broadening is found to be negligible if the V-number of the fibre is much larger than about 20. 相似文献
3.
从理论上分析了影响激光脉冲宽度的因素,建立了脉冲展宽与各影响因素之间的数学模型。通过 Matlab 软件模拟分析了不同因素对脉冲展宽的影响,分析得出在一定条件下,脉冲展宽效果最佳时分束镜反射率 R =0.38,光学腔长 L =940 cm。对 Nd ∶YAG 脉冲激光器纳秒激光进行了脉冲展宽实验,测试了脉冲宽度随着泵浦电压的变化情况。选取了泵浦电压为730 V,分束镜 R 为0.38,在初始脉宽为37 ns 的条件下通过改变腔长将激光脉冲分别展宽到37.5 ns,42 ns 和55 ns,实验数据与理论分析的误差分别0.98%,0.74%和2.1%。实验数据分析验证了建立的数学模型是可行的。 相似文献
4.
5.
6.
7.
8.
9.
Minimum pulse broadening of multimode graded-index fibers is investigated theoretically. Exact solutions of the rms pulse-width σ for a fiber with a power-law index profile is obtained by using the integral expression of group delay time based the multilayer approximation. It is shown that the minimum value of σ and the optimum α for the power-law index profile calculated by the multi-layer approximation in the steady-state modal power distribution are nearly equal to the well-known WKB solution. Next,sigma_{min} and the corresponding αopt are evaluated for certain index imperfections such as a central index dip and sinusoidal index ripple along a radial direction. The results offer the possibility to avoid the bandwidth degradation due to an inevitably generated index tipple in an MCVD graded-index fiber. 相似文献
10.
11.
12.
紫外激光散射通信会引起严重的脉冲展宽效应,由此导致的码间串扰会引起通信误码率。利用紫外光传输模型计算接收信号的时域分布;对“1”码和“0”码包络的概率密度分布按照“11”、“10”、“01”和“00”组合进行卷积,得到在采样时刻两侧相邻码元串扰量的概率密度函数。在引起误码临界值到采样时刻串扰量范围内,对概率密度函数进行积分可得上述4种情况的串扰引起误码的概率。仿真结果表明:距离5 km 的直视通信符号速率须小于9.25×107 Baud;距离1 km 的非直视通信在收发端仰角同为20°、30°和40°时,对应的符号速率须小于4.0×107 Baud、6.0×106 Baud 和3.6×105 Baud。因此,若紫外激光用于低速无线光通信领域可忽略码间串扰的影响。 相似文献
13.
14.
文章通过数值计算研究了掺铒光纤放大器(EDFA)中超短光脉冲放大的情况.结果表明,当相邻两超短脉冲的初始间距较小时,两脉冲在放大过程中会相互吸引,并产生新的子脉冲,从而导致放大效果变差.增大初始间距并不能有效地改善放大效果.为此,提出对输入光脉冲对引入合适的初始啁啾的方法,该方法可以减小因光脉冲互作用带来的负面影响,提高脉冲放大质量. 相似文献
15.
用龙格-库塔算法对描述超高斯脉冲在光纤中传输的微分方程组进行了数值求解,数值结果表明光纤的二阶色散、三阶色散和脉冲初始啁啾使脉宽展宽,光纤非线性对脉宽有压缩作用.求出了能使超高斯脉冲在光纤中持续保形传输的用非线性系数归一化的二阶色散系数,该系数随超高斯脉冲的锐度因子增大而减小.当脉冲不能保形传输时频率与相位出现抖动,由... 相似文献
16.
本文首先提出了含有位置和频率参量的啁啾厄米 -高斯函数 ,然后从非线性薛定谔方程出发 ,用变分法研究了厄米 -高斯型短脉冲在光纤中的传输特性 ,导出了脉冲各参量在光纤中演化的一级近似耦合微分方程组。 相似文献
17.
18.
Dong Wang Wenke Yu Li Huo Xiangyu Jiang Xin Chen Caiyun Lou 《Photonic Network Communications》2016,32(2):213-217
An ultrashort optical pulse generator based on nonlinear pulse shaping is proposed and demonstrated. With a spatial light modulator placed prior to a high nonlinearity fiber, \((\mu +\lambda )\)-evolution strategy is introduced to dynamically adjust the transfer function of spatial light modulator both in phase and in amplitude. Nearly chirp-free 2.2-ps optical Gaussian pulse and 0.73-ps optical Nyquist pulse with a repetition rate of 25 GHz are both achieved in simulation. The scheme also has a certain tolerance to phase quantization error of the spatial light modulator and power fluctuation. 相似文献
19.