中文摘要：

一个简单的光纤定向耦合器可以通过固定耦合斜率和耦合器的长度来设计。耦合系数和耦合器的长度在满足一定的条件下,光纤耦合器可以设计成一个一阶或者二阶光时间微分器。分析了光纤定向耦合器全光微分特性的工作机理,采用皮秒级高斯脉冲输入此光纤耦合器,通过数值仿真该双芯光纤耦合器,分析了其工作误差、工作带宽、能量效率。分析表明,光时间微分器的工作带宽与耦合器的长度和耦合斜率有关;在光时间微分器参数固定后,二阶光时间微分器的工作带宽大约是一阶的2.9倍。与较长的高斯脉冲相比,较短的高斯脉冲通过光纤耦合器,会有较高的能量效率,但同时会产生较大的误差。在实际应用中应根据具体情况设计不同的光时间微分器,来达到预期的目的。

英文摘要：

The transmission properties of a simple fiber-optic directional coupler are determined by coupling slope and the coupler length.When the coupling coefficient and the coupler length meet certain conditions,the optical fiber coupler can be designed as a first-order or second-order optical time differentiator.The operation mechanism of the all-optical differential characteristics of the optical fiber directional coupler is analyzed,and the transmission properties of picosecond Gaussian optical pulse including the operation error,bandwidth and energy efficiency are numerically analyzed for dual-core optical fiber coupler.The result shows that the operating bandwidth of the differentiator is determined by the coupler length and coupling slope.While the optical differentiator parameters are fixed,the operating bandwidth of second-order optical time differentiator is about 2.9 times of that of the first-order differentiator.Compared with a longer Gaussian pulse through the fiber coupler,a shorter Gaussian pulse will produce higher energy efficiency and larger operation errors.An actual optical differentiator could be designed for different intended purposes of practical applications.