光发射机中MZ型波导调制器产生CTB的分析

Analysis of MZ Waveguide Modulator Induced CTB in AM CATV Optical Fiber Externally Modulated Transmitter

AM－CATV外调制光发射机中的MZ型波导调制器，其转移特性呈正弦曲线。当多路信号同时调制时，将产生组合二次失真（CSO）和组合三次差拍（CTB）。本文对CTB进行了理论分析，并对我国450、550MHz二种CATV系统调制时的CTB进行了计算。这对非线性补偿电路的设计具有一定的指导价值。

In optical fiber AM CATV extermally modulated transmitter, Mach-Zenhder modulator is often employed. Nonlinearity of the modulator's output verse voltage would induce composite second order distortion (CSO) and composite triple beat (CTB) in the case of multi-channel modulation. In this paper, CTB is theoretically analysed and simulated on PAL-D 450MHz and 550MHz CATV systems. The result is helpful to nonlinear compensation design.