Shao Haifeng, Chen Weiwei, Zhao Yong, Chi Hao, Yang Jianyi, Jiang Xiaoqing
Department of Information Science and Electronics Engineering, Zhejiang University, Hangzhou 310027, China.
Opt Express. 2012 Mar 26;20(7):7398-403. doi: 10.1364/OE.20.007398.
Silicon photonics has emerged as the premier candidate for the photonic systems-on-chip (SoC). The scheme based on the silicon Mach-Zehnder modulator (MZM) to generate photonic ultra-wideband (UWB) signals is helpful to the integration of the UWB system with other optical networks on a single silicon-based chip. In this paper, according to the influence of the nonlinear free carrier dispersion (FCD) effect and the free carrier absorption (FCA) effect, the performance of two typical UWB generation schemes is numerically analyzed. The double side-band UWB (DSB-UWB) generation scheme needs the DC reverse bias which increases the complexity of the modulator and there is a residual chirp resulting from the FCD effect even the push-pull operation is adopted. The quasi single-sideband UWB (QSSB-UWB) generation scheme doesn't have these problems. However there is the asymmetric amplitude peak in the generated UWB signal. The property of the large singal modulation is also investigated to improve the signal-to-noise ratio (SNR).
硅光子学已成为片上光子系统（SoC）的首要候选技术。基于硅马赫-曾德尔调制器（MZM）生成光子超宽带（UWB）信号的方案，有助于将UWB系统与其他光网络集成在单个硅基芯片上。本文根据非线性自由载流子色散（FCD）效应和自由载流子吸收（FCA）效应的影响，对两种典型的UWB生成方案的性能进行了数值分析。双边带UWB（DSB-UWB）生成方案需要直流反向偏置，这增加了调制器的复杂性，并且即使采用推挽操作，由于FCD效应仍会产生残余啁啾。准单边带UWB（QSSB-UWB）生成方案不存在这些问题。然而，所生成的UWB信号中存在幅度不对称峰值。还研究了大信号调制的特性以提高信噪比（SNR）。
