Hsu Yi-Jang, Lai Yinchieh
Opt Express. 2015 Jan 12;23(1):292-300. doi: 10.1364/OE.23.000292.
Efficient wavelength-selective coupling of lights between sub-wavelength plasmonic waveguides and free space is theoretically investigated. The idea is based on a new type of vertical resonance coupling devices built on plasmonic metal/insulator/metal (MIM) waveguides. The device structure consists of a vertical grating coupler in a resonance cavity formed by two distributed Bragg reflectors (DBRs). With the metal loss included, maximum coupling efficiency around 50% can be obtained at the 1550 nm wavelength with a filtering 3 dB bandwidth around 20 nm (7 nm for the lossless case), demonstrating the feasibility of the idea for achieving high efficiency wavelength-selective vertical coupling through optical resonance. By utilizing this coupler, a plasmonic add-drop device is proposed and theoretically demonstrated. This kind of compact wavelength selective coupling devices shall have the potential to open up a new avenue of photonics circuitry at nanoscale.
从理论上研究了亚波长等离子体波导与自由空间之间光的高效波长选择性耦合。该想法基于一种新型的垂直共振耦合器件，该器件构建在等离子体金属/绝缘体/金属（MIM）波导上。器件结构由位于由两个分布布拉格反射器（DBR）形成的共振腔内的垂直光栅耦合器组成。计入金属损耗后，在1550nm波长处可获得约50%的最大耦合效率，滤波3dB带宽约为20nm（无损情况为7nm），证明了通过光学共振实现高效波长选择性垂直耦合这一想法的可行性。利用这种耦合器，提出并从理论上证明了一种等离子体分插复用器件。这种紧凑的波长选择性耦合器件有望为纳米尺度的光子学电路开辟一条新途径。
