新型四倍频光生毫米波矢量信号调制技术

提出一种基于双并联马赫-曾德尔调制器(MZM)的新型四倍频光生毫米波技术,并用于矢量信号调制。传统的四倍频调制技术,由于数据信号同时调制到+2,-2阶边带上,拍频检测后两个边带上数据信号会产生相位叠加,只适用于不归零码(NRZ)等强度调制格式。提出的矢量信号调制技术将数据信号调制在一个-1阶边带上,另一个+3阶边带不携带数据,在拍频检测后幅度和相位信息被正确保留。同时,四倍频模块降低了传输过程中对电和光器件的带宽需求。理论分析和仿真结果表明,通过此方法产生的携带在60GHz载波上的6.25×108 symbol/s的四相相移键控(QPSK)信号,经过20km单模光纤传输后,误差向量幅度(EVM)损耗可以忽略。

Vector Signal Modulation Technique Based on a Novel Frequency Quadrupling Scheme in Millimeter-Wave Band

A novel frequency quadrupling scheme based on a dual parallel Mach-Zehnder modulator (MZM) for the generation of optical millimeter signal and modulation of the vector signal is demonstrated. The traditional frequency quadrupling modulation scheme, which modulates data on both +2 and -2 order optical sidebands and will cause the constellation overlapping after photodetector (PD) detection, can only carry the on-off keying data format such as not return to zero (NRZ). The proposed scheme encodes the electrical vector signal on the -1 order optical sideband, and a pure radio frequency (RF) tone at +3 order optical sideband. Therefore, phase and amplitude information will be correctly preserved after detection. Besides, a frequency quadrupling scheme is employed to reduce the bandwidth requirements of the electrical and optical components of the transmitter. A proof of concept and simulation is conducted by using a 6.25×108 symbol/s QPSK signal at a carrier frequency of 60 GHz , which indicates that the error vector magnitude (EVM) penalty is negligible after transmission over 20-km single-mode fiber (SMF).