Li Qiang, Qiu Min
Laboratory of Photonics and Microwave Engineering, School of Information and Communication Technology, Royal Institute of Technology (KTH), Electrum 229, 164 40 Kista, Sweden.
Opt Express. 2010 Jul 19;18(15):15531-43. doi: 10.1364/OE.18.015531.
Vertical directional coupling between a metal-insulator-metal (MIM) plasmonic waveguide and a conventional dielectric waveguide is investigated. The coupling length, extinction ratio, insertion loss and coupling efficiency of the hybrid coupler are analyzed. As an example, when the separation between the two waveguides is 250 nm, a maximum coupling efficiency of 73%, an insertion loss of -1.4 dB and an extinction ratio of 16 dB can be achieved at a coupling length of 4.5 microm at 1.55 microm wavelength. A particular feature of this hybrid coupler is that it is highly tolerant to the structural parameters of the plasmonic waveguide and the misalignment between the two waveguides. The performance of this hybrid coupler as a TM polarizer is also analyzed and a maximum extinction ratio of 44 dB and an insertion loss of -0.18 dB can be obtained. The application of this hybrid coupler includes the signal routing between plasmonic waveguides and dielectric waveguides in photonic integrated circuits and the polarization control between TE and TM modes. In addition, it provides an approach for efficiently exciting MIM plasmonic modes with conventional dielectric modes.
研究了金属-绝缘体-金属（MIM）等离子体波导与传统介质波导之间的垂直方向耦合。分析了混合耦合器的耦合长度、消光比、插入损耗和耦合效率。例如，当两个波导之间的间距为250 nm时，在1.55μm波长下，耦合长度为4.5μm时，可实现最大耦合效率73%、插入损耗-1.4 dB和消光比16 dB。这种混合耦合器的一个特殊特点是，它对等离子体波导的结构参数以及两个波导之间的失准具有高度耐受性。还分析了这种混合耦合器作为TM偏振器的性能，可获得最大消光比44 dB和插入损耗-0.18 dB。这种混合耦合器的应用包括光子集成电路中等离子体波导和介质波导之间的信号路由以及TE和TM模式之间的偏振控制。此外，它提供了一种用传统介质模式有效激发MIM等离子体模式的方法。
