• Journal of the Optical Society of Korea
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• v.15 no.1
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• pp.82-89
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• 2011

In this paper, we numerically study both band-pass and band-stop plasmonic filters based on Metal-Insulator-Metal (MIM) waveguides and circular ring resonators. The band-pass filter consists of two MIM waveguides coupled to each other by a circular ring resonator. The band-stop filter is made up of an MIM waveguide coupled laterally to a circular ring resonator. The propagating modes of Surface Plasmon Polaritons (SPPs) are studied in these structures. By substituting a portion of the ring core with air, while the outer dimensions of the ring resonator are kept constant, we illustrate the possibility of red-shift in resonant wavelengths in order to tune the resonance modes of the proposed filters. This feature is useful for integrated circuits in which we have limitations on the outer dimensions of the filter structure and it is not possible to enlarge the dimension of the ring resonator to reach to longer resonant wavelengths. The results are obtained by a 2D finite-difference time-domain (FDTD) method. The introduced structures have potential applications in plasmonic integrated circuits and can be simply fabricated.

• Korean Journal of Optics and Photonics
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• v.28 no.6
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• pp.361-365
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• 2017

In this paper, we demonstrate a facile fabrication technique for a periodically aligned metal nanoparticle array, for a narrow-band plasmonic absorber. The metal nanoparticles are fabricated by e-beam evaporation and heat treatment processes on top of a periodic aluminum groove template. The plasmonic absorber is constructed with the transferred metal nanoparticle array, sputtered 33-nm-thick $Al_2O_3$, and 200-nm-thick metal reflector layers on silicon substrate. 46-nm-diameter and 76-nm-lattice metal-nanoparticle-array-based plasmonic absorber has performed as a narrow-band absorber with a central wavelength of 572 nm and full width at half maximum (FWHM) of 109.9 nm.

• Journal of the Optical Society of Korea
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• v.15 no.2
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• pp.118-123
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• 2011

A novel triangular-shaped plasmonic metal-insulator-metal (MIM) Bragg grating waveguide is introduced, whose band-gap is narrower than that of the conventional step type and wider than that of the sawtoothshaped one. Moreover apodized triangular-shaped MIM Bragg grating structures are proposed in order to reduce the side lobes of the transmission spectrum, because the Bragg reflector with a sawtooth profile has a smoother transmission spectrum than that of a triangular-shaped one. The performance of the proposed structures is simulated by using the finite difference time domain method.

• Applied Science and Convergence Technology
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• v.27 no.4
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• pp.75-77
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• 2018

The electrostatic interaction between emerging quantum-confined nanostructures with plasmonic structures is crucial for future biological applications. Water-soluble green fluorescent copper nanoparticles (Cu-NPs) were fabricated. We demonstrate that L-ascorbic acid is considered as a key to precisely control small Cu-NPs and the capability of the surface ligands, while cetyltrimethylammonium bromide is used as a stabilizing agent controls the particle growth, and stabilizes the nanoparticles. Water-soluble green fluorescent Cu-NPs are tunable through modification of the reaction periods.

• Korean Journal of Optics and Photonics
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• v.35 no.1
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• pp.24-29
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• 2024

We propose a hyperbolic metastructure based on a nanopatterned metal (Ag)-dielectric (PDMS) multilayer and report on its performance in an infrared (IR) cut-off filter for imaging devices. By optimizing the size of the square-shaped Ag nanopattern and the thickness of PDMS surrounding the Ag nanopattern, the proposed IR cut-off filter blocks 99% of light in the 0.70-1.01 ㎛ wavelength band while maintaining a high transmittance of over 94% in the visible region. Here, the cut-off wavelength band starts at a region above the epsilon-near-zero wavelength of the hyperbolic metastructure and ends at the point where plasmonic absorption appears strongly. It is observed that transmittance in the wavelength region longer than the IR cut-off band increases again due to plasmonic coupling among horizontally adjacent Ag nanopatterns. This metastructure can improve the performance of IR-blocking filters as well as allow it to be manufactured ultra-thin, which is applicable to various planar optical elements and integrated optical components.

• Korean Journal of Optics and Photonics
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• v.29 no.6
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• pp.275-284
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• 2018

In this study we propose a hybrid color-filter design method in which a nanohole array and a nanodisk array are separated by nanopillars of the material AZ 1500. We propose a design method for an RGB color filter, using the tendency of transmitted light according to each design variable. Especially we analyzed the intensity distribution of the electric field in the cross section, and set the height of the nanopillars so that the local surface-plasmon resonances generated in the two different arrays do not affect each other. The optical characteristics of the optimized color filter are as follows: In the case of the red filter, the ratio of the wavelength band expressing red in the visible broadband is 55.01%, and the maximum transmittance is 41.53%. In the case of the green filter, the ratio of the wavelength band expressing green is 40.20%, and the maximum transmittance is 42.41%. In the case of the blue filter, the ratio of the wavelength band expressing blue is 32.78%, and the maximum transmittance is 30.27%. We expect to improve the characteristics of color filters integrated in industrial devices by this study.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2005.06a
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• pp.102-103
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• 2005

Using THz time-domain spectroscopy, we study plasmonic band gaps in periodic metal arrays of slits. Femtosecnd machining system guarantees good quality sub millimeter structures for THz spectroscopy. Fabry-Perot effect enhances the transmission when the two resonances cross but does not alter the surface plasmon peak positions.

• Journal of the Optical Society of Korea
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• v.18 no.3
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• pp.261-273
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• 2014

In this paper, metal insulator metal (MIM) plasmonic slot cavity narrow band-pass filters (NBPFs) are studied. The metal and dielectric of the structures are silver (Ag) and air, respectively. To improve the quality factor and attenuation range, two novel NBPFs based on tapered structures and double cavity systems are proposed and numerically analyzed by using the two-dimensional (2-D) finite difference time domain (FDTD) method. The impact of different parameters on the transmission spectrum is scrutinized. We have shown that increasing the cavities' lengths increases the resonance wavelength in a linear relationship, and also increases the quality factor, and simultaneously the attenuation of the wave transmitted through the cavities. Furthermore, increasing the slope of tapers of the input and output waveguides decreases attenuation of the wave transmitted through the waveguide, but simultaneously decreases the quality factor, hence there should be a trade-off between loss and quality factor. However, the idea of adding tapers to the waveguides' discontinuities of the simple structure helps us to improve the device total performance, such as quality factor for the single cavity and attenuation range for the double cavity. According to the proposed NBPFs, two, three, and four-port power splitters functioning at 1320 nm and novel ultra-compact two-wavelength and triple-wavelength demultiplexers in the range of 1300-1550 nm are proposed and the impacts of different parameters on their performances are numerically investigated. The idea of using tapered waveguides at the structure discontinuities facilitates the design of ultra-compact demultiplexers and splitters.

• Advances in nano research
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• v.3 no.3
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• pp.133-141
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• 2015

Influence of Ag nanoparticles on optical and photovoltaic properties of, silicon substrates, silicon solar cells and glass have been investigated. Silver nanoparticles have been fabricated by evaporation of thin Ag layers followed by the thermal annealing. The surface plasmon resonance peak was observed in the absorbance spectrum at 470 nm of glass with deposited silver nanoparticles. It is demonstrated that deposition of silver nanoparticles on silicon substrates was accompanied with a significant decrease in reflectance at the wavelength 360-1100 nm and increase of the absorption at wavelengths close to the band gap for Si substrates. We studied influence of Ag nanoparticles on photovoltaic characteristics of silicon solar cells without and with common use antireflection coating (ARC). It is shown that silver nanoparticles deposited onto the front surface of the solar cells without ARC led to increase in the photocurrent density by 39% comparing to cells without Ag nanoparticles. Contrary to this, solar cells with Ag nanoparticles deposited on front surface with ARC discovered decrease in photocurrent density. The improved performance of investigated cells was attributed to Ag-plasmonic excitations that reduce the reflectance from the silicon surface and ultimately leads to the enhanced light absorption in the cell. This study showed possibility of application of Ag nanoparticles for the improvement of the conversion efficiency of waferbased silicon solar cells instead of usual ARC.

• Journal of the Optical Society of Korea
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• v.6 no.3
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• pp.83-86
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• 2002

Nanoscopic emission from periodic nano-hole arrays in thick metal films is studied experimentally. The experiments give direct evidence for SP excitations in such structures. We show that the symmetry of the emission is governed by polarization and its shape is defined the interference of SP waves of different diffraction orders. Near-Held pattern analysis combined with the far-Held reflection and transmission measurements suggests that the SP eigenmodes of these arrays may be understood as those of ionic plasmon molecules.