Abstract

Nanogap antennas are compelling structures for squeezing light into ultrasmall volumes. However, when gaps are shrunk to the nanometer scale, the mode losses dramatically increase. In this Letter, we report the conditions of critical coupling between the arrays of nanogap resonant metal-insulator-metal (MIM) antennas and free space. Adapting the antenna density, critical coupling is achievable for any thickness of insulator, from 100 down to 0.1 nm. The fundamental optical mode can be described as continuous transitions through three types of modes: a perfect MIM mode, coupling between the MIM mode and surface plasmon polariton, and a gap plasmon mode. We found that the space between adjacent antennas is an essential parameter to perform critical coupling for thinner gaps. These results pave the way towards understanding extreme confinement in nanogap antenna structures such as MIM or nanoparticle arrays.

© 2019 Optical Society of America

Hybrid modes in a single thermally excited asymmetric dimer antenna

Loubnan Abou-Hamdan, Claire Li, Riad Haidar, Valentina Krachmalnicoff, Patrick Bouchon, and Yannick De Wilde
Opt. Lett. 46(5) 981-984 (2021)

Nano-antenna enhanced waveguide integrated light source based on an MIS tunnel junction

Baohu Huang, Siping Gao, Yan Liu, Jian Wang, Zhenguo Liu, Yongxin Guo, and Weibing Lu
Opt. Lett. 44(9) 2330-2333 (2019)

Unidirectional launching and elongating propagation of airy surface plasmon polaritons by a metasurface coupling grating

Jin Jiang, Fengkai Meng, Yang Zhao, Zheyu Fang, and Feng Lin
Opt. Lett. 44(11) 2815-2818 (2019)

Miniaturizing nanoantennas with hybrid photonic-plasmonic modes for improved metasurfaces

Yoav Chachamovitz and Guy Bartal
Opt. Lett. 45(17) 4871-4874 (2020)

Spoof surface plasmon-based stripe antennas with extreme field enhancement in the terahertz regime

Zhanghua Han, Yusheng Zhang, and Sergey I. Bozhevolnyi
Opt. Lett. 40(11) 2533-2536 (2015)