Browsing by Subject "Electro-optic"

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Open Access
Functional nanoplasmonic devicesand novel photonic materials
(2015) Battal, Enes
Plasmonics is one of the pillars of nanophotonics involving light matter interactions. Its applications found very wide range covering photovoltaics, photodetection, optical communication, surface enhanced infrared absorption and Raman spectroscopy, infrared and THz imaging. Although the number of applications is very high, the underlying plasmonic structures are limited. In this thesis, we utilize a common plasmonic resonator structure namely metal-insulator-metal (MIM resonators) to realize active beam steering in the infrared spectrum. We investigate radiation characteristics of a phased array antenna formed by MIM resonators. Materials-wise, low intrinsic loss, CMOS compatibility and bio-compatibility are among the crucial requirements for various applications of plasmonics. Noble metals are the dominant materials used in plasmonics to get high localization of the incident field among which gold and silver face serious challenges due to high intrinsic loss and lack of CMOS compatibility. We introduce InN as a novel plasmonic material thanks to its high concentration of free carriers and investigate its optical characteristics in the IR spectrum. We form a proof-of-concept absorber and investigate its plasmon excitation characteristics. On the other hand, we introduce another material ZnO, nonplasmonic, suitable for infrared imaging purposes with strong absorption characteristics. Optical modulators are at the very heart of active light manipulation technologies such as integrated optics, bio-sensing, telecommunications, radio frequency and terahertz applications. Although various modulation schemes have been realized, the underlying mechanisms providing modulation did not change significantly. The common modulation methods can be listed as free carrier dispersion, thermo-optic method, use of liquid crystals, magneto-optical, optically nonlinear materials and recently introduced solid-state phase-change materials. Here we introduce another mechanism called resistive switching for optical modulation in the infrared spectrum. We investigate electrical resistive switching characteristics of an Al/ZnO/Si stack and optical modulation characteristics under electrical bias. We obtain hysteretic modulation in the reflection spectrum. We also investigate the thermo-optic modulation characteristics of atomic layer deposited ZnO through spectroscopic ellipsometry and realization of actively reconfigurable reflector surface.
Open Access
Graphene-enabled optoelectronics on paper
(American Chemical Society, 2016-06) Polat, E. O.; Uzlu, H. B.; Balci, O.; Kakenov, N.; Kovalska, E.; Kocabas, C.
The realization of optoelectronic devices on paper has been an outstanding challenge due to the large surface roughness and incompatible nature of paper with optical materials. Here, we demonstrate a new class of optoelectronic devices on a piece of printing paper using graphene as an electrically reconfigurable optical medium. Our approach relies on electro-modulation of optical properties of multilayer graphene on paper via blocking the interband electronic transitions. The paper based devices yield high optical contrast in the visible spectrum with a fast response. Pattering graphene into multiple pixels, folding paper into three-dimensional shapes or printing colored ink on paper substrates enable us to demonstrate novel optoelectronic devices which cannot be realized with wafer-based techniques.