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Nonlinear Localized Modes in Photonic Crystals
Park, Q-Han Optical Society of Korea 2002 Current Optics and Photonics Vol.6 No.3
We give a brief overview of nonlinear localized modes in photonic crystals. We explain how photonic crystals can potentially be important in making small scale active devices which operate in an all optical way. Two models to approach nonlinear photonic crystals, the coupled mode theory and the discrete lattice theory using a Green's function, are explained.
Optical Properties of Tunable Metalic Nano-Tubes by Using an Interband Transition
Q.-Han Park,W. J. Choi,Dong Hyuk Park,Jinsoo Joo 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.3
The optical properties of a tunable metal-coated nano polymer are described in this study. The optical properties of metal-coated nano-polymer tubes are calculated by using a Finite- Difference Time-Domain (FDTD) method. To calculate the metalic part in the tube, we used Drude's model with the FDTD method. To obtain the optical properties, we also applied the optical theorem to the FDTD method. The optical properties of metals come from their optical constants and plasmonic structure. We calculate two kinds of metals, nickel and silver, to show the tunable optical properties. Also, we analyze the tubes by changing the thicknes of the metal coating. We verify tunable optical properties for silver by using an interband transition.
Effect of Metallic Slab Cladding on Photonic Crystal Band Structures
Q-Han Park,Jong-Ho Choe,Heonsu Jeon 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
We study the effect of a metal cladding on the band structure of a two-dimensional photonic crystal slab. In this paper, we present some photonic band structures of square and triangular lattice-hole-patterned photonic crystal slabs. The results for the perfect electric conductor (PEC) or the metal cladding cases are shown. We used both the plane wave expansion (PWE) method and the nite-difference time-domain (FDTD) method and we compared them to each other. We explain how each cladding changes the band structure and we suggest the amount of change, especially at the Γ point in the photonic band diagram.
Propagation properties in a dressed photonic crystal waveguide
S.H. Han,Y. S. Park,Y. Roh,Q-Han Park,H.S. Jeon 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.1
We present a novel method for reducing the radiative loss in photonic crystal waveguide (PCW) structures. By dressing a slab PCW with omni-directional mirrors, we demonstrate numerically that the coupling of propagation modes of PCW to external radiative modes can be signicantly reduced. Waveguide properties of a dressed PCW such as defect modes, mini stop bands and group velocity are explained in detail. In particular, the re ection and the transmission at the bent slab PCW and the bent dressed PCW are compared by measuring the standing wave ratio. We also point out a possibility for leakage-free guidance of light in a dressed PCW with characteristic design parameters.
Design and evaluation of mobile offloading system for web-centric devices
Park, S.,Chen, Q.,Han, H.,Yeom, H.Y. Academic Press 2014 JOURNAL OF NETWORK AND COMPUTER APPLICATIONS - Vol.40 No.-
Increasingly, smartphones are becoming one of the most popular mobile devices in the personal computing environment. As the need for a variety of mobile applications increases, the target mobile platform is a primary concern for mobile application developers. To reduce design complexity for different platforms and enhance the compatibility of applications on various mobile OSes, a JavaScript-based web environment became a main target framework for smartphone applications. Two particular characteristics of a smartphone are restricted power supply and low-end hardware resources, compared to high-end servers. Computing-intensive and rich graphics-based applications in a smartphone may fully utilize the CPU and consume a large amount of the battery power accordingly. In this paper, we propose a platform-independent mobile offloading system, which is a delegated system for a web centric devices environment. Our offloading architecture uses a built-in proxy system that splits the original JavaScript-based application codes into the following two parts: a lightweight code for the mobile client and a computationally heavy code that runs on the server system. We adopt one of the web applications utilizing a combinatory search for our case study. Our evaluation shows that our mobile offloading system reduces the response time of the application running in the web browser and enables a high workload application to run on relatively low-end mobile devices. In addition, this method reduces power consumption of the device. Therefore, this web-based offloading architecture creates a new mobile computing environment and supports various OS platforms of mobile clients.