One major obstacle in developing plasmonic devices is dissipative loss. SPPs decay as they travel along the metal due to the conversion of optical energy to heat. These losses severely limit the performance of metal-based plasmonic devices at optical frequencies. In this talk, I will present two examples of structured dispersion induced plasmonics where the dissipation losses are dramatically suppressed. In the first example, low-loss surface modes are realized via engineered mode dispersion in an all-dielectric waveguide below the cutoff frequency [1, 2]. This approach enables the realization of transformational plasmonic resonators capable of harvesting light over a broadband continuous spectrum . In the second example, I will show how two coupled corrugated metal strips can induce spoof surface modes with negative group velocities. With a judicious design, the effective refractive indices at the fundamental and harmonic frequencies can fulfill the backward phase-matching condition n(2ω) = -n(ω) with negligible dissipation losses. The microwave experiment confirms the efficient backward harmonic generation with a conversion efficiency as high as 3.2%. These studies reveal that spoof plasmonics provides an ideal low-loss platform to enhance various plasmonic phenomenon.
Keywords: Plasmonics, broadband light harvesting, second harmonic generation
 C. D. Giovampaola and N. Engheta, "Plasmonics without negative dielectrics," Phys. Rev. B 93, 195152 (2016).
 Z. Li, L. Liu, H. Sun, Y. Sun, C. Gu, X. Chen, Y. Liu, Y. Luo, "Effective Surface Plasmon Polaritons Induced by Modal Dispersion in a Waveguide, " Phys. Rev. Applied 7, 044028 (2017).
 J. B. Pendry, Y. Luo, and R. Zhao, "Transforming the optical landscape," Science, 348, 521-524 (2015).
Yu Luo received the B.E. degree in Electronic & Information Engineering from Zhejiang University, China, in 2006, and Ph.D. in physics from Imperial College London, UK, in 2012. He then remained in Imperial College London as a research associate after graduation. In 2015, he joined the School of Electrical and Electronic Engineering, Nanyang Technological University, as an assistant professor. Luo’s research interests focus on metamaterials and plasmonics ranging from the design of invisibility cloaks and plasmonic light-harvesting devices to the study of nonlocal and quantum phenomena in mesoscopic plasmonic systems. He has published more than 70 international refereed journal papers which have received over 2,000 citations.