针对光纤无线通信(ROF)系统对光强调制器线性度的特殊要求,设计了一种新型的集成光学器件——微环相位辅助型马赫曾德尔调制器(RPAMZM)。将一个微环谐振器和一个相位调制器分别加载到马赫曾德尔调制器的两臂,可以补偿普通马赫曾德尔调制器的亚线性,得到线性度良好的响应特性。建立了该种器件的理论分析模型,计算了不同条件下的传输特性和无毛刺动态范围(SFDR)。分析结果表明,在不计损耗的情况下,器件的非线性主要来源于传输函数泰勒展式的三次项,通过控制透射系数,可以使该项等于零,无毛刺动态范围获得19.68 dB的提高;在损耗存在的情况下,通过控制透射系数和偏压因子,可以同时抑制掉二次和三次这两个主要的非线性项,无毛刺动态范围获得15.74 dB的相对改善。

A novel scheme for linearity improvement of optical modulator is proposed for radio over fiber (ROF) system. This modulator is named ring and phase assisted Mach-Zehnder modulator (RPAMZM). A microring and a phase modulator are coupled to each arm of a normal Mach-Zehnder modulator respectively in order to compensate its sublinear characteristics transfer. Analyses under loss-less condition, loss condition and spur-free dynamic range (SFDR) are proposed. It is found that a high linearity can be achieved by properly setting the coupling coefficient under lossless condition. A corresponding SFDR of 19.68dB is achieved. When loss is considered, the main nonlinear terms, including the 2nd and the 3rd term, can be eliminated by properly setting the coupling coefficient and bias point. A corresponding SFDR of 15.74 dB can be achieved.