利用半导体光放大器进行光脉冲消基座的理论研究

提出了一种利用半导体光放大器(SOA)联合可调谐光滤波器进行高阶孤子压缩消基座的新方法.进行了详尽的理论分析和优化.数值计算表明,在一定条件下,这种方法能够在不展宽脉冲的前提下,对基座进行有效地抑制.     

四阶色散对飞秒高斯脉冲传输的影响

推导了考虑二、三、四阶色散的高斯脉冲传输方程;利用计算机数值模拟的方法,研究了四阶色散(FOD)对飞秒高斯脉冲在单模光纤中传输特性的影响.模拟结果显示：只有在入射脉冲宽度窄到飞秒量级时,即对应传输速率很高的情况下,FOD对脉冲的影响才明显;FOD导致脉冲形状发生了畸变,畸变特点不同于二、三阶色散;随着初始脉宽逐渐减小,FOD所致的飞秒高斯脉冲畸变经历了一个脉冲仅仅展宽,到展宽脉冲的两翼出现“底座”,到展宽脉冲的两翼出现具有微小振荡“底座”的变化过程.     

Numerical study on adiabatic compression of ultrashort fundamental solitons in an erbium-doped fiber amplifier

In this paper, the compression and amplification of fundamental solitons in an erbium-doped fiber amplifier (EDFA) are investigated by using the numerical method. The results show that the unchirped fundamental solitons can be compressed and amplified by selecting an appropriate length of the EDFA when the peak gain of the EDFA is fixed, and the compression and amplification satisfy the adiabatic condition. Furthermore, the fundamental solitons with appropriate positive chirp parameters can be compressed and amplified effectively by selecting an appropriate length of the EDFA, but the pulse compression cannot satisfy the adiabatic condition. Moreover, the compression of the fundamental solitons with negative chirp also cannot satisfy the adiabatic condition, and the compression effects are very poor. Thus, the chirp should be reduced before adiabatic compression using the EDFA.     

Effect of global plasma parameters on the transition of edge pedestal properties in jϕ−α space

We have derived analytic expressions for the variation of the normalized pressure gradient and current density in the edge pedestal in terms of global plasma parameters. Comparison of our model with numerical results shows good agreement. Our model has been applied to explain the behavior of pedestal width and height when the plasma parameters change. The transition of the equilibrium point with the change of plasma parameters for the same pedestal width in the ${\mathit{j}}_{?}-\alpha$ space is calculated using our model. The growth or contraction of the edge pedestal can then be determined if the new stability boundary is known.