Wang, C.M.C.M.WangChang, Y.C.Y.C.ChangTsai, M.W.M.W.TsaiYe, Y.H.Y.H.YeChen, C.Y.C.Y.ChenJiang, Y.W.Y.W.JiangSI-CHEN LEETsai, D.P.D.P.Tsai2020-06-112020-06-11200810411135https://scholars.lib.ntu.edu.tw/handle/123456789/498845https://www.scopus.com/inward/record.uri?eid=2-s2.0-65149103549&doi=10.1109%2fLPT.2008.924320&partnerID=40&md5=08dbb356094c62468ee3295e44d06685A plasmonic infrared (IR) filter was experimentally and theoretically investigated. A localized surface plasmon polariton (LSPP) mode which was angle-independent in almost fully incident angle was observed. Through the use of the LSPP mode, an IR reflection-type notch filter with an ultrahigh immunity for the angular deviation was realized. An angle-independent reflection dip was designed at λ = 6.2 μm with a full-width at half-maximum of 0.5 μm. The experimental result shows that the position and the line shape of the resonant dip at λ = 6.2 μm remain the same for an increasing incident angle from 20° to 60°. The optical properties can be engineered by tuning thickness of the cavity layer. The proposed notch filter presents a large angular tolerance means that the superior angular stability makes it more feasible as it is put into practical applications. © 2008 IEEE.Filters; PlasmonicsAngle-independent; Angular deviations; Cavity layers; Incident angles; Infrared filters; IR reflection; Line shape; Localized surface plasmon; Plasmonics; Notch filters; Optical properties; Phonons; Photons; Plasmons; Quantum theory; Surface plasmon resonancejournal article10.1109/LPT.2008.9243202-s2.0-65149103549