为了实现相位调制光信号的相位混合运算(2θA-θB、2θB-θA), 描述了简并四波混频光互调效应的工作原理, 给出了泵浦消耗情形下四波混频闲频光振幅和相位的解析表达式。重点研究了基于高非线性光纤的相位混合运算器件的实现方案, 以四进制相位信号为例分析了输入光幅度噪声对两种相位互调运算结果的影响。仿真计算表明, 该运算器件的光噪声指数(光信噪比的劣化)约为6.6 dB; 当输入光信噪比不低于25 dB时, 两种运算的符号错误率均低于10-3, 对应的误差矢量振幅约为22%。

In order to realize hybrid arithmetic functions (2θA-θB、2θB-θA) of phase-modulated signals, we describe the operating principle of optical phase inter-modulation in degenerate Four-Wave Mixing (FWM) process, and present the analytic solution of the degenerate FWM equations in the pump depletion case. A typical hybrid arithmetic scheme using highly nonlinear fiber is studied in detail. As an example, the influence of input amplitude noise on the hybrid arithmetic calculator for two quaternary signals is analyzed. It is shown that the calculator has an optical noise figure or Optical Signal-to-Noise Ratio (OSNR) degradation of about 6.6 dB. It is also indicated that the input OSNR should be more than about 25 dB for a symbol-error rate of ≤10-3, corresponding to the Error Vector Magnitude (EVM) smaller than 22%.