基于多频相位调制的光学单边带调制器研究

提出了一种基于多频相位调制技术实现光学单边 带调制信号产生的新型方案。当含有基频和谐波成分的多频调制信号施加到Mach-Zehnder( MZ)电光调制器上时,若驱动信号波 形选取合适,可使调制后的光信号功率集中在边带谱的一个频率成分上,其它频率成分被抑 制, 从而获得光学单边带调制信号的输出。以十频相位调制为例,计算了与之对应的光学单边带 调 制信号的光谱结构,其中信号能量利用率近88%,载波抑制比大于24dB,边频抑制比大于18 d B, 从理论上证明了本文所述方案的可行性。进一步的仿真结果显示,随着驱动信号谐波数的增 加, 载波抑制比、边频抑制比和信号能量利用率均逐渐增大。可见,为了获得优质的光学单边带 调 制信号,应在实际条件允许的情况下使用尽可能多的调制频率。此方案能量利用率相对较高 , 仅用到了一级商用MZ相位调制器,方案结构简单,是一种产生光学单边带调制信号的有效途 径。

Numerical research on optical single sideband modulator generated by multi-freq uency phase modulation

In this paper,a novel scheme for optical single side-band signal gen eration based on multi-frequency modulation is proposed.When a modulation signal containing fu ndamental frequency and harmonic waves was loaded onto a Mach-Zehnder electro-optic modu lator,most of the optical power would concentrate on one sideband,while other frequency component s were suppressed, and made a single sideband signal.As an example,the signal spectrum generate d by 10-tones phase modulation was numerically calculated.Energy efficiency up to 88%,carrier su ppression ratio of 24dB and sideband suppression ratio of 18dB were obtained in our simulation,w hich indicates that the proposed scheme is feasible and efficient.Further simulation results show t hat the energy efficiency,carrier suppression ratio and the sideband suppression ratio all rise with the increase of the number of harmonic waves. Thus it can be seen that to get optical single sideband signal with high quility,as many modulation frequencies as possible should be used if the ex periment condition satisfied.Commercial Mach-Zehnder electro-optic mudulator and RF driver were used in our scheme,wh ich makes the virtue of high energy efficiency and simple configuration for operation.It prov ides an effective way to generate an OSSB signal for optical communication or optical sensing systems.