• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1089-1093
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• 2003

The moving least square (MLS) basis is implemented for the real-space band-structure calculation of 2D photonic crystals. The value-periodic MLS shape function is thus used in order to represent the periodicity of crystal lattice. Any periodic function can properly be reproduced using this shape function. Matrix eigenequations, derived from the macroscopic Maxwell equations, are then solved to obtain photonic band structures. Through numerical examples of several lattice structures, the MLS-based method is proved to be a promising scheme for predicting band gaps of photonic crystals.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.1
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• pp.61-66
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• 2009

Characteristics of the photonic bandgaps (PEGs) in two-dimensional photonic crystals (2D PCs) with a square lattice have theoretically studied using a finite difference time domain (FDTD) simulation. In this paper, we propose a concept of optical coverage ratio (OCR) as a new structural parameter to determine the PEGs for E-polarized light. The OCR is an optically compensated filling factor. It is possible to normalize the PEGs of 2D PCs by introducing the OCR.

• Macromolecular Research
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• v.14 no.2
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• pp.155-165
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• 2006

The present article describes the experimental and theoretical observations on the formation of holographic, polymer-dispersed, liquid crystals and electrically switchable, photonic crystals. A phase diagram of the starting mixture of nematic liquid crystal and photo-reactive triacrylate monomer was established by means of differential scanning calorimetry (DSC) and cloud point measurement. Photolithographic patterns were imprinted on the starting mixture of LC/triacrylate via multi-beam interference. A similar study was extended to a dendrimer/photocurative mixture as well as to a single component system (tetra-acrylate). Theoretical modeling and numerical simulation were carried out based on the combination of Flory-Huggins free energy of mixing and Maier-Saupe free energy of nematic ordering. The combined free energy densities were incorporated into the time-dependent Ginzburg-Landau (Model C) equations coupled with the photopolymerization rate equation to elucidate the spatio-temporal structure growth. The 2-D photonic structures thus simulated were consistent with the experimental observations. Furthermore, 3-D simulation was performed to guide the fabrication of assorted photonic crystals under various beam-geometries. Electro-optical performance such as diffraction efficiency was evaluated during the pattern photopolymerization process and also as a function of driving voltage.

• Journal of the Optical Society of Korea
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• v.19 no.1
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• pp.63-68
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• 2015

A one-step fabrication of a photonic crystal (PC) with functional defects is demonstrated. Using multi-beam phase-controlled holographic lithography with a diffracting optical element, large area one dimensional (1D) and two dimensional (2D) PCs with periodic defects were fabricated. The uniform area is up to $2mm^2$, and tens of defect channels have been introduced in the 1D and 2D PC structure. This technique gives rise to substantial reduction in the fabrication complexity and significant improvement in the spatial accuracy of introducing functional defects in photonic crystals. This method can also be used to design and fabricate three dimensional (3D) PCs with periodic defects.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.38-38
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• 2009

Characteristics of the photonic bandgaps (PBGs) in two-dimensional photonic crystals (2D PCs) with a hexagonal lattice have theoretically studied using a finite difference time domain (FDTD) simulation. In this research, we propose a concept of optical coverage ratio (OCR) as a new structural parameter to determine the PBGs for E-polarized light. The OCR is an optically compensated filling factor. It is possible to normalize the PBGs of 2D PCs by introducing the OCR.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.12
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• pp.831-836
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• 2014

One-dimensional (1D) photonic crystals (PCs) were prepared by $TeO_x(2<x<3)/SiO_2$ with the difference refractive index, and fabricated by sputtering technique from a $TeO_2$ and $SiO_2$ target. The $TeO_x$(2$Ar:O_2=40:10$). A 10-pair $TeO_x(2<x<3)/SiO_2$ 1D PCs were fabricated with the structure parameters of filling factor=0.5185, and period=410 nm. The properties of 1D PCs with and without a defect layer were evaluated by UV-VIS-NIR. A normal mode 1D PC have a photonic band gap (PBG) in the near infrared (NIR) region from 1,203 to 1,421 nm. In the case of 1D PC containing a defect layer, a defect level appears at 1,291 nm. The measured transmittance (T) spectra are nearly corresponding to calculated results. After He-Cd laser exposure, the defect level is shifted from 1,291 nm to 1,304 nm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.515-521
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• 2003

There are now many theoretical investigations and real manufactures for numerous applications of photonic crystals (PCs) associated with photonic band gap and photonic integrated circuits. However, there are some difficulties to design and fabricate the desired pattern quality. It is not easy to satisfy accurate critical dimension (CD) for patterns with arbitrary shapes and pitch sizes aligned in various directions. In this work, we report the optimum conditions to better fabricate and design, and greatly improve pattern quality in delineating two-dimensional (2D) PCs in the nanometer range using single- step e-beam lithography system with conventional exposure mode.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.594-597
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• 2008

This presentation introduces a simple strategy for producing 2D photonic crystal layers (PCL) with different structures. In an attempt to improve extraction efficiency from the thin film phosphors (TFPs), this study have examined the effects of the structural variables of the 2D PCLs on the light extraction efficiency of TFPs.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.134.2-134.2
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• 2014

Photonic crystal solar cells have the potential for addressing the disparate length scales in polymer photovoltaic materials, thereby confronting the major challenge in solar cell technology: efficiency. One must achieve simultaneously an efficient absorption of photons with effective carrier extraction. Unfortunately the two processes have opposing requirements. Efficient absorption of light calls for thicker PV active layers whereas carrier transport always benefits from thinner ones, and this dichotomy is at the heart of an efficiency/cost conundrum that has kept solar energy expensive relative to fossil fuels. This dichotomy persists over the entire solar spectrum but increasingly so near a semiconductor's band edge where absorption is weak. We report a 2-D, photonic crystal morphology that enhances the efficiency of organic photovoltaic cells relative to conventional planar cells. The morphology is developed by patterning an organic photoactive bulk heterojunction blend of Poly(3-(2-methyl-2-hexylcarboxylate) thiophene-co-thiophene) and PCBM via PRINT, a nano-embossing method that lends itself to large area fabrication of nanostructures. The photonic crystal cell morphology increases photocurrents generally, and particularly through the excitation of resonant modes near the band edge of the organic PV material. The device performance of the photonic crystal cell showed a nearly doubled increase in efficiency relative to conventional planar cell designs. Photonic crystals can also enhance performance of other optoelectronic devices including organic laser.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.2
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• pp.99-103
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• 2015

One-dimensional photonic crystals (1D PCs) were fabricated by RF sputtering technique on p-Si (100), and fused quartz substrates. The 1D PCs structures consisted of $TeO_x$ (x=1.42), and $SiO_2$ with the difference refractive index. In order to estimate the effect on a defect level within 1D PCs structures, samples were prepared with both normal, and defect mode. The structural and optical properties were confirmed by Scanning electron microscope (SEM), and Ultraviolet visible near-infrared spectrophotometer (UV-VIS-NIR) respectively. In the case of a 1D PC normal mode without defect layer, it had a photonic band gap (PBG) in the near infrared (NIR) region. In the case of a 1D PC defect mode with defect layer, it had a sharp transmission band owing to a defect level, and moved towards the longer wavelength after exposing He-Cd laser with a wavelength of 325 nm.