基于LiNbO_3 M-Z调制器的UWB信号PAM调制技术研究

Research of ultra-wideband pulse amplitude modulation based on LiNbO_3 Mach-Zehnder modulator

提出一种基于LiNbO3Mach-Zehnde调制器(MZM)实现超宽带(UWB)脉冲幅度调制(PAM)的方案,只利用一个LiNbO3-MZM,实现幅度调制,结构简单,易于实现。利用OptiSys-tem7.0软件对方案进行了仿真,研究了调制信号的传输特性,并分析了光源功率、光源波长、脉冲宽度、调制速率、延迟时间以及传输距离对调制信号的影响。

We propose a modulation scheme of ultra-wideband （UWB） pulse amplitude based on a lithium niobate Maeh-Zehnder modulator （LiNbO3 MZM）. In the scheme, the clock signal is added to the electric signal, and pulse amplitude modulation （PAM） can be realized by this method. The scheme is simple and integrated easily. By using the software of OptiSystem 7.0 ,the generated ultra-wideband （UWB） monocycles with different power levels of laser device （LD）, different optical carrier wavelengths, different input signal pulse widths, different modulation rates, different time delays and different transmission distances are experimentally studied and analyzed. The results show that this scheme has good tolerance to the input signal pulse width, and it is insensitive to the wavelength change. This shceme also has good performance in transmission, and the modulated signal can transmit for 10 km. In order to get distortion- less modulated signal, the power of LD and modulation rate must be within a certain range. According to the analysis,the maximum of laser power is 6 dBm and the modulation rate is 30 Gbit/s. The time delay sjhould be controlled in a permissible range of inaccuracy. Overall, this scheme has considerable advantages, and the output signal can satisfy the existing communication system needs.