Optimization of nanocavity field enhancement using two-dimensional plasmonic photonic crystals

• 来源期刊: 科学通报(英文版)
• 学科: 工学
• 年，卷（期）: 2012,（1）
• 页码范围: 77-82
• 页数: 6页
• 分类号: TN629.1
• 语种: 中文

摘要

We have investigated the influence of Ag nanorod radius(r)on the resonant modes of a two-dimensional plasmonic photonic crystal(PPC)with dipole sources embedded into the central vacancy area,using finite-difference time-domain methods.Both the localized surface plasmon(LSP)mode of individual Ag nanorods and the resonant cavity mode of PPC are found to vary as a function of r.The resonant cavity mode is strongly enhanced as r is increased,while the LSP signal will eventually become no longer discernable in the Fourier spectrum of the time-evolved field.An optimized condition for the nanocavity field enhancement is found for a given PPC periodicity(e.g.d=375 nm)with the critical nanorod radius rc=d/3.At this point the resonant cavity mode has the strongest field enhancement,best field confinement and largest Q-factor.We attribute this to competition between the blocking of cavity confined light to radiate out when the cavity resonant frequency falls inside the opened photonic stopband as r reaches rc,and the transfer of cavity mode energy to inter-particle plasmons when r is further increased.