双环推挽型高线性M-Z光强调制器特性研究

Linearity of Microring-assisted Push-Pull Mach-Zehnder Intensity Modulator

对损耗影响下的双环推挽(TRAPP)型马赫-曾德(M-Z)光调制器的线性特性进行了研究。分析表明,存在损耗时,设计特定的光微环与M-Z干涉臂间的耦合大小,并控制偏置点,总可以获得2次与3次高阶项为零的调制曲线;当微环1周损耗小于5 dB时,线性范围总是可以达到90%以上;当损耗过大时,导致基于微环的全通滤波器的相位响应受限,虽然调制曲线在自身范围内依然保持高的线性度,但调制曲线固有的调制深度将限制整体线性范围。

Linearity of the M-Z modulator with the two-ring-assisted push-pull（TRAPP） configuration was studied under the loss influence. It was found that the linearity of the TRA-MZ modulator is greatly high, even at the low-loss condition. By properly setting the biasing phases,the 2^rd- and 3^rd-order harmonic terms of the modulation curves can be removed. The maximum linearity range is larger than 90% when the round-trip loss of the microrings is less than 6 dB. Analysis shows that the output phase of the microring-based all-pass filter will vary only within a limited range if the loss of the microring is very large, and the maximum modulation depth of the TRA-MZ modulator will be less than unit and become the major factor that reduces the linearity range though the modulation curve of the TRA-MZ modulator is still in high linearity within its modulation depth.