• Journal of the Optical Society of Korea
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• v.7 no.1
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• pp.13-19
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• 2003

The effects of strain distribution in quantum wire arrays have been analyzed using a finite-element method including both the hydrostatic and shear strain components. Their effects on the optical properties of the quantum wire arrays are assessed for various types of stress profiles by calculating the optical gain and the polarization dependence. The results show unique polarization dependency, which can be exploited either for the single polarization or the polarization-independent operation in quantum wire photonic devices.

• Current Photovoltaic Research
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• v.5 no.2
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• pp.55-58
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• 2017

We investigated the influences of dielectric thin film coating on the optical characteristics of c-Si wafers with nanocone (NC) arrays using finite-difference time-domain (FDTD) simulations. Dielectric thin films on high-refractive-index surface can lower optical reflection and reflection dips appear at the wavelengths where destructive interference occurs. The optical reflection of the NC arrays was lower than that of the dielectric-coated planar wafer in broad wavelength range. Remarkable antireflection effects of the NC array could be attributed to beneficial roles of the NCs, including the graded refractive index, multiple reflection, diffraction, and Mie resonance. Dielectric thin films modified the optical reflection spectra of the NC arrays, which could not be explained by the interference alone. The optical properties of the dielectric-coated NC arrays were determined by the inherent optical characteristics of the NC arrays.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.99-102
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• 1989

Optical implementation of adaptive quadratic associative memory for two-dimensional patterns is described by using holographic lenslet arrays and spatial light modulators. Basic experimental results demonstrating its feasibility are reported.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.19-31
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• 2005

During the last decade, the exploration of nanoscale device and circuitry based on molecules has gained increasing interest. In parallel with this, considerable effort is being devoted to the development of molecular photonic/electronic materials based on various porphyrin arrays. This involves light as an input/output signal and excitation energy migration as a mechanism for signal transmission. Absorption of a photon at the light collector end of the porphyrin array yields the excited state, which migrates among the intervening pigments until reaching the emitter, whereupon another photon is emitted. As a consequence, it is relevant to understand the excitation energy transfer (EET) processes occurring in various forms of porphyrin arrays for the applications as artificial light harvesting arrays and molecular photonic/electronic wires. Since the excitonic (dipole) and electronic (conjugation) couplings between the adjacent porphyrin moieties in porphyrin arrays govern the EET processes, we have characterized the EET rates of various forms of multiporphyrin arrays (linear, cyclic, and box) based on various time-resolved spectroscopic measurements. We believe that our observations provide a platform for further development of molecular photonic/electronic materials based on porphyrin arrays.

• Journal of the Optical Society of Korea
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• v.7 no.1
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• pp.7-12
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• 2003

A numerical approach for the analysis of quantum wire structures has been presented using a finite-element method which includes the strain analysis and the band analysis of the Luttinger-Kohn Hamiltonian with the deformation potential. A systematic implementation of the multiband Hamiltonian in the finite-element scheme is outlined and the corresponding variational functional is derived for arbitrarily shaped strained quantum wire arrays. This method is then applied to calculate the band structures of strained quantum wire arrays.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.126-130
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• 1990

A single-layer Perceptron with 4x4 input neurons and one output neuron is optically implemented. Holo-graphic lenslet arrays are usee for the programmable optical interconnection topology. The hologram is bleached in order to increase the diffraction efficiency. It is shown that the performance of Perceptron depends on the learning rate, the inertia rate, and the correlation of input patterns.

• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.438-443
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• 2010

In this paper, behaviors of photonic crystal (PC) radiative structures and antenna arrays have been compared for two types of uniform and binomial excitations. Appropriate duality has been shown between them. These results can be generalized to other types of excitation and arrangement of photonic crystal radiative arrays such as linear, planar and circular arrays of three dimensional (3D) photonic crystal termination resonators. Using these results in designing photonic circuits has some advantages for shaping a particular radiative beam at the photonic crystal exit, for instance reducing the divergence angle of the main lobe in order to enhance the directivity, for better coupling, or for splitting the emitted beam, for dividing the output beam to the next devices in photonic integrated circuits (PIC). For analysis and simulation of the photonic crystal structures, the finite difference time domain (FDTD) method has been employed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.191-192
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• 2012

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1984.10a
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• pp.25-27
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• 1984

Using LED sources, the system that performs optical logic function of the input data arrays will be presented. Sixteen possible functions of two binary data arrays, such as AND, OR, NOR and XOR are simply obtained in parallel by controlling LED switching mode. Experimental result and some examples of application will be given.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.197-201
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• 2008

Conformational heterogeneity of directly linked multiporphyrin arrays with larger molecular length retards their utilities in practical applications such as two-photon absorption and molecular photonic wire. In this regard, here we adopted a way to overcome the conformational heterogeneity through hydrogen bonding by selective binding of meso aryl substituents of porphyrins (host) with urea (guest) to form helical structure. Using steady-state and time-resolved spectroscopy, we observed the enhanced fluorescence quantum yield by ~1.8 to 2.4 times, enhanced anisotropy values and the disappearance of fast fluorescence decay component in the host-guest helical forms. In addition, the enhanced nonlinear optical responses of helical arrays infer the extended inter-porphyrin electronic coupling due to a significant change in dihedral angle between the neighboring porphyrin moieties. The current host-guest strategy will provide a guideline to improve the structural homogeneity of the photonic wire.