• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.163-168
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• 2023

In this paper, a novel platform for chemical sensing and biosensing is presented. The working principle is based on the coupling efficiency and interference properties of optical directional coupler (DC) and multimode interference coupler (MMIC). It has been realized using planar technology to allow integration on a silicon substrate. Firstly, the dispersion curves of DC and MMIC is described, and the design specification of an optimized slot optical waveguide to increase waveguide sensitivity is selected. Next, the sensor response to the refractive index change of sensing analyte is numerically simulated. The numerical results reveal that high effective index change per refractive index unit (RIU) change of analyte is obtained, and the sensitivity can be tuned using the DC and MMIC design technique.

• KSBB Journal
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• v.15 no.3
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• pp.254-261
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• 2000

A bacterial leaching was conducted for pyrite with Thiobacillus ferrooxidans(ATcC 19859) and Thiobacillus KY isolated from acid mine water around Kwangyang area to characterize the surface of substrate as reaction progress at the optimum condition under 9K medium for 3- days. It was found that the surface crystallinity changes referred to hkl plane was observed for 20 days leached by T. ferrooxidans similar changes also observed for 10 days leached pyrite by Thiobacillus KY. Based on he results of SEM-EDS the atomic ratios of Fe, S and Si on the surface were changed to sulfur rich phase but exposed Si ratio decreased from 16.94% to 4.85% during 30days mainly due to reprecipitating of Fe and S as a mixed compound.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.4
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• pp.45-52
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• 2000

We present a novel method for simple and efficient analysis of the rectangular MQW waveguide. Preferentially two-dimensional structure is transformed into one-dimensional structure by using the effective index method. Then, the characteristic matrix of the resultant planar MQW waveguide is analyzed by scanning angle method. The effective index, modal intensity, and optical confinement factor of rectangular MQW waveguide can be effectively obtained by this method. Our simulation results show excellent agreement with the accurate solutions based on the finite element method. We also introduce the approximation methods for the analysis of rectangular MQW waveguide and investigate their validity. By using perturbation approach, modal power loss of guided wave in rectangular MQW waveguide is newly investigated and compared with the conventional method using the approximation of planar MQW waveguide.

• Korean Journal of Optics and Photonics
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• v.13 no.6
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• pp.461-466
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• 2002

Fiber-optic comb filters using a side-polished fiber coupler are proposed as multi-channel isolation filters on wavelength division multiplexing systems. We have demonstrated that the coupling efficiency between two waveguides is improved by the intermediate coupling layer in spite of the decrease of the optical power transfer between two waveguides due to the high-order modes of the overlay waveguide coupled with the side-polished single-mode fiber. When LiNbO$_3$with a 200-${\mu}{\textrm}{m}$-thickness was applied as a planar-overlay-waveguide, the comb filtering characteristics with a 4 nm-channel-spacing were achieved and the maximum power coupling occurred at the 1-${\mu}{\textrm}{m}$-thickness and the refractive index in range 1.52 to 1.53 of an intermediate coupling layer. If the intermediate coupling layer is optimized, an extinction ratio with more than 20 dB can be obtained. These experimental results are in good agreement with the BPM simulation.

• Korean Journal of Optics and Photonics
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• v.10 no.4
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• pp.311-317
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• 1999

Unidirectional single-mode operation of a diode-pumped Nd:YAG laser with a planar semimonolithic ring cavity has been demostrated at 1064 nm. The semimonolithic cavity consists of a laser active medium placed in a magnetic field, a crystal quartz plate, and an output coupling mirror. They form an optical diode by acting each part as a Faraday rotator, a reciprocal polarization rotator and a partial polarizer, respectively. An eigenpolarization theory for the cavity configuration was presented and losses for the eigenmodes were calculated. A pump-limited single-mode output power of 155 mW and a slope efficiency of 17% were obtained when the laser was pumped by a 1.2 W, 809 nm diode-laser. A laser linewidth of less than 100 kHz is inferred from a beat note frequency spectrum between two identical laser systems and continous single-mode tuning range was more than 2 GHz.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.489-496
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• 2019

In this paper, we design and fabricate an ultra small dual crossed dipole antenna operating at 2.4 GHz frequency. In order to miniaturize the size of the antenna so that it can be applied to a mobile device, a cross dipole is disposed on the upper two layers and a reflection plane, a horizontal matching circuit and a ground plane are arranged on each layer. The circuit was connected by a vertical through-hole. The size of the fabricated antenna is $21.61mm{\times}16.88mm{\times}1.27mm$, the measured reflection coefficient is -31.5 dB, and the bandwidth below -10 dB is 112 MHz. In addition, since the gain of the antenna is -4 dBi, it has the omnidirectional radiation characteristic, so it can be applied to various fields as an antenna for mobile devices.

• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.142-145
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• 2003

The nonreciprocal phase shift characteristics of infinite slab optical waveguides with magneto-optic materials in the cladding layer was calculated at 1.55 ${\mu}{\textrm}{m}$ for optical isolators. The infinite slab waveguide structures considered in this paper were as follows. rho magneto-optic materials used as a cladding layer were Ce:YIG and LNB(LuNdBi)$_3$(FeAl)$_{5}$)$_{12}$,). Their specific Faraday rotations Θ$_{F}$ are 4500$^{\circ}$/cm, 500$^{\circ}$/cm at wavelength 1.55 ${\mu}{\textrm}{m}$ respectively. The guiding layer with multi-quantum well structure was used, and it consists of 1.3Q and InGaAs. In order to investigate the effect of evanescent field penetrating the cadding, layer, guiding mode characteristics were calculated for the cases when the substrate is InP and air. We calculated the minimum lengths of 90$^{\circ}$ nonreciprocal phase shifters and their optimum guiding layer thicknesses in various optical waveguide structures.res.s.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.12
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• pp.1376-1381
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• 2012

Optical devices are used extensively in the field of information network. Increasing demand for optical device, optical interconnection has been a important issue for commercialization. However many problems exist in the interconnection between optical device and optical fiber, and in the case of the multi-channel, problems of the optical alignment and optical array arise. For solving the alignment and array problem of optical device and the optical fiber, we fabricated fiber alignment and array by using imprint technology. Achieved higher precision of optical fiber alignment and array due to fabricating using imprint technology. The silicon stamp with different depth was fabricated using the conventional photolithography. Using the silicon stamp, a nickel stamp was fabricated by electroforming process. We conducted imprint process using the nickel stamp with different depth. The optical alignment and array by fabricating the patterns of optical device and fiber alignment and array using imprint process, and achieved higher precision of decreasing the dimensional error of the patterns by optimization of process. The fabricated optical interconnection of PLC device was measured 3.9 dB and 4.2 dB, lower than criteria specified by international standard.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11B
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• pp.707-721
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• 2005

Recently, there has been a dramatic increase in data traffic, driven primarily by the explosive growth of the Internet. Optical networking is believed as a key solution to keep up with the growth, thus, the most pressing issue is how to manage and control large optical networks. Currently, provisioning end-to-end connections across the transport network has involved the network operator, leading to long provisioning times in an era when customers are demanding shorter provisioning time. To address this critical issue, new control intelligence is being studied for use within optical networks to shorten provisioning time. Both the IETF and the ITU-T have been aggressively defining many aspects of a control plane for the next generation convergence transport network. Basically, they are based on the distributed control scheme. In this Paper, we suey the applicability of the centralized control scheme for the provisioning control of optical transport network to utilize its inherent advantages over the distributed control scheme. We discuss new central control architecture, and control procedure. Also, we examine the applicability of the existing IETF routing and signaling protocols to the new control concepts, and then, we propose the additional routing and signaling information elements.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.6
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• pp.53-58
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• 2004

A novel UV sensor was manufactured and characterized using evanescent field coupling between photochromic dye dispersed polymer waveguide and side polished fiber. The spiroxazine (photochromic dye) dispersed polymer was used as planar waveguides. The resonant wavelength was shifted owing to refractive index variation of planar waveguide on exposed UV because of its photo-functional properties. The sensitivities are $1.21{\mu}W/mw$ and $2.75{\mu}W/mw$ when UV intensities increased after exposure times were fixed at 3 seconds and 5 seconds, respectively. Output optical power according to UV intensity increases and saturation time decreases as the intensity of UV radiations increases.