• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.11
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• pp.577-582
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• 2004

In this paper, lumped equivalent circuits for a conventional parallel directional coupler are proposed. This equivalent circuits only have self inductance and self capacitance, so we can design exact lumped equivalent circuit. The equivalent circuit and design formula for the presented lumped element coupler is derived based on the even- and odd-mode properties of parallel-coupled line. By using the derived design formula, we have designed the 3dB and 4.7dB MMIC couplers at the center frequency of 3.4GHz and 5.6GHz respectively. Measurements for the designed MMIC directional couplers show at 4dB and 5.2dB-coupling value at the center frequency of 3.4GHz and 5.6GHz. Excellent agreements between simulation results and measurement results on the designed directional couplers show the validity of this paper

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.5
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• pp.910-923
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• 1992

Experimental verification of numerical results is conducted by measuring the dynamic strains of mid-points of the coupler and the lever for the 4-bar linkage mechanism with rigid bearing and flexible bearing, respectively. For the axial strain of lever mid-point, the numerical results including geometric stiffness almost agree with the experimental ones, however, the numerical results excluding geometric stiffness almost agree with the experimental ones for the axial strain of coupler mid-point. It is supposed that these phenomena should be caused by the fact that the motion of the coupler is more complicated than of the lever. The signals of dynamic strains of coupler and lever mid-points, measured by strain gages, are transformed into frequency domain by fast fourier transformer. From this experiment, the lst resonance frequencies of the coupler and the lever are obtained. It is made clear that the former almost agrees with the fundamental and the latter the 2nd mode natural frequency of the mechanism system calculated by numerical analysis.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.313-316
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• 2000

Concentric-Circle-Grating (CCG) cavity is analyzed by coupled mode theory. In this case concentric grating is acting as both feedback element and output coupler. In our calculations radiation loss terms are included in guided coupled mode equations. The surface-emitted field distribution is obtained in self-consistent manner.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.1
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• pp.39-46
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• 2002

High-senstivity temperature sensor based on the wavelength selectivity of single mode fiber-to-planar waveguide coupler, was demonstrated. The resonant wavelength of the coupler was shifted with large rate of -3.43nm/$^{\circ}C$ owing to good thermo-optic effects of polymer planar waveguide. The device design technique to reduce the polarization dependent properties and increase the temperature sensitivity was presented.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.7
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• pp.25-31
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• 1998

Modal transmission-line is utilized to analyze the power coupling of optical directional coupler composed by two parallel guiding slabs. By defining a coupling efficiency .eta. amenable to rigorous supermodes and boundary conditions of modal functions, we evaluate the power transfer for TE mode of gainy coupler. The results reveal that optimized power exchange occurs at a novel wavelength .lambda.$_{op}$ , which is generally different from minimum gap .lambda.$_{min}$ between rigorous modes and phase-matching condition .lambda.$_{ph}$ .

• The Journal of the Acoustical Society of Korea
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• v.3 no.2
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• pp.23-29
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• 1984

In this paper surface acoustic wave beam track changers using symmetric multistrip coupler are designed on the basis of the perturbation theory, and its characteristics are studied. SAW beam track changers, which have the configuratio of the periodic array of metal strips, are designed with the following specifications ; the number of strips : 140, the strip period: 0.25λ, the ratios of the strip width to the period a/p: 0.5, 0.375, 0.25, respectively, and approximately consistent with the theoretical values, and also the bulk wave mode and the 2nd-order effects are suppressed by these track changers.

• Korean Journal of Optics and Photonics
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• v.2 no.1
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• pp.20-25
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• 1991

Using evanescent field coupling between single ($LP_{01}$) and double ($LP_{01}, LP_{11}$) mode optical fiber, we selected LPII mode beam. With a $LP_{11}$ mode beam from a double mode fiber. we fabricated $LP_{11}$ mode fiber optic resonant ring interferometer, and assured that the guided mode is $LP_{11}$ mode from a radiation beam coming through the prism output coupler. When an external perturbation applied to the signal arm of the $LP_{11}$ fiber optic resonant ring interferometer, we examined the change of radiation mode coming from a prism output coupler and an end of optical fiber. Using two photodiode, LPn mode beam converted to voltage. This two output voltages is applied to X and Y terminal of oscilloscope to display circular motion on oscilloscope.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.8
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• pp.1108-1116
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• 1993

Y-branch directional coupler optica1 switches with two different coupling lengths are fabricated on z-cut LiNbO3 and tested at r = 1.3 rm. The normal mode and coupled mode theories are utilized to calculate device coupling length and switching voltage. Simulation of the beam propagation method (BPM) is also performed to confirm the device coupling lengths. For dc operation, experimental results are in good agreement with the modee theories expectation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.4
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• pp.278-285
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• 1990

It is well know that optical oupler that is composed of the polished single-mode optical fiber can separate two arbitrary wave lengths. Wavelength division ranges of the WDM optical coupler that is made of the bending fiber with radius R vary with the center wavelength of the signal and spacing between two cores. In this paper, when optical fiber is fixed with the radius R, We proposed the spacing between two cores that can provide minimum division range. Also, We proposed the minimum radius R necessary to separate two arbitary wavelengths of the signal.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.165-170
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• 2016

Nano-scale power splitter based on curved plasmonic waveguides are designed by utilizing the multimode interference (MMI) coupler. To analyze easily the adaptive properties of plasmonic curverd multimode interference coupler(PC-MMIC), the curved form transforms equivalently into a planar form by using conformal transformation method. Also, effective dielectric method and longitudinal modal transmission-line theory are used for simulating the light propagation and optimizing the structural parameters at 3-D guiding geometry. The designed $2{\times}2$ PC-MMIC does not work well for quasi-TM mode case due to the bending structure, and it does not exist 3dB coupling property, in which the power splitting ratio is 50%:50%, for quasi-TE mode case. Further, the coupling efficiency is better when the signal is incident at channel with large curvature radius than small curvature radius.