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频率锁定多载波光源是实现太比特系统传输的关键器件之一,目前已成为光纤通信领域的研究热点.基于循环频移技术产生的频率锁定多载波光源因具有驱动电压低、串扰小、平坦度高的优点而受到重视,但是其输出质量容易受到调制器固有的高阶谐波串扰的影响,特别是三阶谐波串扰.为了减小三阶串扰的影响,本文提出了在I/Q调制器两支路上再加载另一频率为3fm的射频信号的方案,用其产生的一阶信号来抑制三阶串扰.通过理论分析与数值仿真,得到了载波数为24、载波间最大功率差小于0.1 dB的多载波光源输出.与未采用三阶串扰抑制方案的结果比较,光源输出有效光信噪比提高了2 dB.结果表明,采用本文的改进方案,可以有效地提高多载波光源的输出平坦度和有效光信噪比.
Frequency-locked multi-carrier light source is one of the key devices to realize terabit system transmission, and has become a hotspot in the field of optical fiber communication at present.Frequency locked multi-carrier light source based on cyclic frequency shift technology has the advantages of low driving voltage, small crosstalk, flatness However, its output quality is easily affected by the high-order harmonic crosstalk inherent in the modulator, especially the third-order harmonic crosstalk. In order to reduce the influence of the third-order crosstalk, The other two paths are loaded with another RF signal with the frequency of 3fm and the first-order signal is used to suppress the third-order crosstalk.Through theoretical analysis and numerical simulation, the number of carriers is 24 and the maximum power difference between carriers is less than 0.1 dB multi-carrier light source output.Compared with the third-order crosstalk suppression scheme, the effective optical signal-to-noise ratio of the light source output increased by 2 dB.The results show that the improved scheme of this paper can effectively improve the multi-carrier light source output Flatness and effective optical signal to noise ratio.