Functional Terahertz Nanodevices and Their Applications

Dr. Minah Seo,
Director's Postdoctoral Fellow, Los Alamos National Laboratory

ABSTRACT: 
Terahertz (THz) technology can encompass a wide range of applications in electronics and photonics, and contribute to their fundamental science as well as its potential impact on engineering applications. In these hidden frequencies, development of metamaterials has played an increasingly important role especially in the construction of functional THz devices such as filters, switches, and sensors, since there is a limit of natural dielectric responses for most of materials in these frequencies. Metamaterials are artificially structured materials, introduced to overcome the limit of natural dielectric responses and to get a desirable resonance tuning over broad bandwidths. The dielectric properties of these metamaterials, changeable by optical, electrical, or thermal means, with or without lateral patterns, are in turn used to control entire optical frequencies which further extend metamaterials performance. Development of tunable and actively controllable metamaterials with extremely high gain as electro-optic devices at terahertz frequencies will be shown in this presentation. Terahertz wave transmission through subwavelength apertures in nano scale is controlled by temperature and photo excitation driven refractive index change of substrate. Remarkably, the nanogap-patterned device allows the extinction to fall by four orders of magnitudes with completely shutting-off the resonance characteristics. Furthermore several new types of ultrafast optical microscopy techniques especially for the study of time resolved carrier dynamics on single semiconductor nano materials will be introduced in this talk. Finally this research will contribute on the highly sensitive terahertz sensing and ultrafast optical microscopy for variety of chemistry, biology and medical applications.

BIOGRAPHY:               
Minah Seo received M.S. (2005) and Ph.D. (2010) degrees in Physics from Seoul National University in Seoul, South Korea. Her dissertation work for Ph.D. is about terahertz spectroscopy on plasmonic materials, semiconductor thin films and CNTs, and terahertz electromagnetic wave control by using actively controlled metamaterial, honored by outstanding doctoral dissertation award from Seoul National University in 2010. She has developed and accomplished a research on the topic of terahertz near field imaging of plasmonic structures, which inspired the further new project on the topic of terahertz-nano-plasmonics. Minah is currently Director’s postdoctoral fellow at Los Alamos National Laboratory since 2010, concentrating on ultrafast mid-to-far-infrared dynamics in individual semiconductor nanowires and in plasmonic metamaterials with high temporal and spatial resolution. She has authored over 30 refereed journal publications and two US and international patents.