Deng Hong, Bogaerts Wim
Opt Express. 2019 Sep 16;27(19):27191-27201. doi: 10.1364/OE.27.027191.
Plasma dispersion modulators (PDMs), such as carrier injection modulators and carrier depletion modulators, are widely used for high speed phase modulation in silicon photonic circuits, but they suffer from spurious intensity modulation. This can be a problem in coherent communication systems that make use of complex multi-level quadrature modulation formats, as well as analog applications such as microwave photonics. In this article, a method to achieve pure phase modulation using PDMs is proposed based on a configurable modulator circuit. The configurable modulator is implemented as a Mach-Zehnder interferometer with a PDM and tunable couplers (TCs). The spurious intensity modulation of the phase modulated lightwave can be compensated by tuning the coupling ratios of the TCs and the phase delay between the two arms of the MZI. Simulation results show that for a depletion modulator, the 1.26 dB spurious intensity modulation can be suppressed down to 0.023 dB within a phase range of 0.4, and for injection modulator, the 1.27 dB spurious intensity modulation can be suppressed down to 0.07 dB within a phase range of 0.76.
等离子体色散调制器（PDM），如载流子注入调制器和载流子耗尽调制器，广泛应用于硅光子电路中的高速相位调制，但它们存在杂散强度调制问题。这在使用复杂多级正交调制格式的相干通信系统以及诸如微波光子学等模拟应用中可能会成为一个问题。在本文中，基于一种可配置调制器电路，提出了一种使用PDM实现纯相位调制的方法。该可配置调制器被实现为一个带有PDM和可调谐耦合器（TC）的马赫-曾德尔干涉仪。通过调整TC的耦合比和马赫-曾德尔干涉仪两臂之间的相位延迟，可以补偿相位调制光波的杂散强度调制。仿真结果表明，对于耗尽调制器，在0.4的相位范围内，1.26 dB的杂散强度调制可被抑制至0.023 dB；对于注入调制器，在0.76的相位范围内，1.27 dB的杂散强度调制可被抑制至0.07 dB。
