Invited Paper
Single-Crystalline Silver Structures for Low-Loss Linear and Nonlinear Plasmonics

Shangjr (Felix) Gwo Department of Physics, National Tsing-Hua University, Hsinchu, Taiwan Chun-Yuan Wang Department of Physics, National Tsing-Hua University, Hsinchu, Taiwan Hung-Ying Chen Department of Physics, National Tsing-Hua University, Hsinchu, Taiwan Liuyang Sun Department of Physics, The University of Texas at Austin, Austin, Texas, USA Wei-Liang Chen Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan Yu-Ming Chang Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan Hyeyoung Ahn Department of Photonics, National Chiao-Tung University, Hsinchu, Taiwan Xiaoqin Li Department of Physics, The University of Texas at Austin, Austin, Texas, USA

It is well known that silver (Ag) is the best plasmonic material at optical frequencies due to its lowest intrinsic loss among all metals. However, additional scattering losses originated from grain boundaries and surface roughness limit the performance of polycrystalline Ag plasmonic systems prepared by conventional techniques. As a result, the ultimate performance of silver for plasmonic applications has not been fully tested. Therefore, the development of ultrasmooth, macroscopic-sized Ag crystals that exhibit much reduced scattering loss and high spatial uniformity is very important and can lead to cascaded and integrated plasmonic devices with reproducible characteristics. In this talk, we will present our recent advances in establishing an optimized material platform for low-loss linear and nonlinear plasmonic applications.

More specifically, we report the synthesis of giant colloidal Ag single-crystals with millimeter lateral size and tens of microns in thickness. Using these Ag crystals, we have achieved record-breaking surface plasmon polariton (SPP) propagation lengths beyond 100 mm in the red wavelength region. These lengths even exceed the predicted propagation lengths using the widely cited optical constants by Johnson and Christy. Furthermore, these crystals allow for the fabrication of highly tunable and reproducible plasmonic nanostructures by focused ion beam (FIB) milling. We have designed and fabricated novel double-resonant “V”-shaped nanogroove arrays on these crystals. Using these tailor-made plasmonic structures, we demonstrate spatially uniform and spectrally tunable second-harmonic generation (SHG) originated from strong plasmon enhancement effects. In contrast to nonlinear signal generation using local hot spots on either randomly roughened films or top-down fabricated plasmonic antenna arrays, our method based on this single-crystalline Ag platform leads to nonlinear plasmonics over a larger sample area with dramatically improved uniformity and controllability.

gwo@phys.nthu.edu.tw









Powered by Eventact EMS