内嵌矩形金属块纳米圆盘结构等离子体多通道波分复用器研究

A Plasmon Multi-Channel Wavelength-Division Multiplexer Constructed with a Nanodisk Structure Embedded in a Rectangular Metal Block

提出了一种内嵌矩形金属块纳米圆盘结构,利用该结构形成的法布里-珀罗腔来加强表面等离激元的耦合作用。该结构具有窄带宽高品质因子的滤波性能,可通过多腔耦合形成多通道波分复用器。采用时域有限差分方法讨论有无内嵌矩形金属块和金属块的横纵向宽度及耦合距离对强透射现象的影响,并根据其透射特性实现多通道波分复用器。研究发现,当圆盘谐振器内嵌矩形金属块后,滤波器具有较好的强透射现象,其半峰全宽显著降低,品质因子增加;通过耦合多个内嵌矩形金属块圆盘谐振器构建的等离子多通道波分复用器,可实现双通道及三通道解复用功能,各信道共振波长可通过谐振腔内嵌的金属块参数来调整,传输效率可达到70%,最小插入损耗为1.549dB,平均工作范围为189nm,且不存在相邻信道串扰。这说明该结构具有较好的解复用分频特性。

This study aims to propose a nanodisk structure embedding a rectangular metal block. The Fabry-Perot cavity formed by this structure is used to enhance the coupling effect of the surface plasmons. The structure has a narrow bandwidth, high quality factor, and high filtering performance. Herein, a multi-channel wavelength-division multiplexer is constructed by multiple cavities coupling. The influence of the horizontal and vertical widths of the rectangular metal block and the coupling distances between the embedded disk and rectangular metal block on the transmission characteristics of the device is described with the time-domain finite-difference method, for which a device without embedded rectangular metal block is used as the control group. A multi-channel wavelength division multiplexer is realized according to its transmission characteristics. The filter shows strong transmission characteristics when the disk resonance filter is embedded in the rectangular metal block;its full width at half maximum is significantly reduced and the quality factor is increased. By coupling a number of inline rectangular-metal-block/disk resonators, we construct the filter. Such plasmon multi-channel wavelength-division multiplexers can provide two- and three-channel demultiplexing functions. The resonant wavelength of each channel can be adjusted by selection of the parameters of the embedded metal block in the resonator, the transmission efficiency can reach up to 70%, and the minimum insertion loss is 1.549 dB. The average operating range is 189 nm, and there is no adjacent-channel crosstalk. We demonstrate that the proposed structure has good de-multiplexing frequency characteristics.