• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.983-986
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• 1998

Inthis paper, we design 4$\times$4 optical star coupler with tapered coupling structure. The 4$\times$4 optical star coupler consists of four 3dB couplers and a 100% coupler with tapered structure. This star coupler is designed by the 2 dimension FD-BPM(finite difference beam propagation method) using TBC(transparent boundary condition). consequently, the maximum power unbalance ratios of relative output power from each of the output waveguides for each of input guides are less than 0.1dB, and the transmission efficiency is more than 99%.

• Journal of the Optical Society of Korea
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• v.11 no.3
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• pp.113-117
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• 2007

A LED light coupler is proposed for coupling light from a mini side LED of 0.4 mm height to a very thin (${\sim}0.3 mm$) light guide. Due to the ultra thinness of the light guide, conventional light couplings between LEDs and light guides do not provide adequate coupling efficiency. The designed LED coupler is a compound lens of 3.5 mm length, 1.2 mm height, and 3.3 mm width. The courier first collimates the light from the LED and then concentrates the light in a manner similar to a compound parabolic concentrate, (CPC) into the light guide. The exit surface of the coupler is additionally textured to have micro patterns in order to control the radiance profile.

• Korean Journal of Optics and Photonics
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• v.20 no.2
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• pp.128-133
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• 2009

In this paper, an optical touch panel device is newly proposed, with operating principle based on the optical coupling between a pointing pen having a built-in light source and perpendicularly crossed optical waveguide arrays. In order to enable an external light to couple into a waveguide core, the auxiliary pyramidal structures are introduced into all intersecting points located periodically along optical waveguides. The shape is optimized for minimizing the unwanted propagation loss due to the same structure by a ray tracing method. For the optical waveguide with the size of $50{\times}50{\mu}m^2$, the bottom width, height, and slope angle of the optimized pyramidal structure are $50{\mu}m$, $22.5{\mu}m$, and $42^{\circ}$, respectively. The optical coupling efficiency of about 97.8% and the average propagation loss of 0.3 dB/mm were achieved for the optimized touch panel. Finally, it is found from the tolerance analysis that tilting of the pen up to ${\pm}12^{\circ}$ can be allowed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5A
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• pp.674-681
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• 2000

We proposed polymer based vertical asymmetric optical coupler. And we optimized the proposed device by coupling characteristic analysis In 1.33um wavelength, TE mode, we obtained very short coupling length(L=277.6um), high coupling efficiency(94%). The merits of proposed device are low propagation loss due to very short full device, low production cost and time, and high integrated fabrication. We will use this to fabricate optical switch, modulator and tunable WDM devices, etc.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.945-948
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• 2000

The coupling properties of supermodes guided by grating-assisted directional couplers (GADCs) can be phrased in rigorous modal theory. Such a modal solution for TE modes expressed by simple electrical transmission-line networks is utilized to analyze the power distribution of GADCS with three guiding channels. In particular, the modal transmission-line theory can serve as a template for computational algorithms that systematically evaluate the coupling efficiency that are not readily obtained by other methods.

• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.500-506
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• 1999

We designed and fabricated a bidirectional optical transceiver module for low cost access network. An integrated chip forming a pin-PD on an 1.3 urn FP-LD was assembled by flip-chip bonding on a Si optical bench, a single mode fiber with an angled end facet was aligned passively with the integrated chip on V-groove of Si-optical bench. Gaussian beam theory was applied to evaluate the coupling coefficients as a function of some parameters such as alignment distance, angle of fiber end facet, vertical alignment error. The theory is also used to search the bottle-neck between transmittance and receiving coupling efficiency in the bi-directional optical system. Tn this paper, we confirmed that reduction of coupling efficiency by the vertical alignment error between laser beam and fiber core axis can be compensated by controlling the fiber facet angle. In the fabrication of sub-module, a'||'&'||' we made such that the fiber facet have a corn shape with an angled facet only core part, the reflection of transmitted laser beam from the fiber facet could be minimized below -35 dE in alignment distance of 2: 30 /J.m. In the same condition, transmitted output power of -12.1 dEm and responsivity of 0.2. AIW were obtained.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1355-1360
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• 2003

Currently, product of optical collimator for optical communication is depending on handiwork, and some companies are propelling semi-automatic system composite of manual and automatic operations. In this point of time, the importance of automatic system of optical collimator for optical communication is taking its place as a core technology in the development of parts with high-efficiency of optical communication. In order to develop such an optical collimator in this study, we designed an automatic assembly system, and developed a software for the system operation. At a result of that, we could carry out a single work process individually running processes of collimator fabrication, a constant work process constantly running all of the processes, and performance evaluation of the collimator.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.145-150
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• 2023

Non-uniform optical taper waveguides have been widely used as devices for high-efficiency mode coupling, as they are integrated with single-mode optical fibers or photonic crystal waveguides. In this paper, we present a new platform for chemical sensing and bio-sensing using optical taper waveguides with these characteristics. The principle of operation is based on the coupling efficiency and interference properties of optical directional coupler (DC) and multi-mode interference coupler (MMIC). First, the curvature characteristics of taper sections of DC and MMIC is explained, and the design specifications of optimized taper waveguide to increase waveguide sensitivity is selected. Next, the sensor response to the change in refractive index of sensing analyte is numerically analyzed. Numerical results show that as the length of couplers increases, the effective index per change in refractive index unit (RIU) of analyte increases, and that sensitivity can be tuned using taper DC and MMIC design techniques.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.212-213
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• 2003

집적 광학(Integrated Optics) 소자에서 기존 광도파로와 광결정 도파로 간의 효율적 결합 및 접속의 안정성은 매우 중요한 과제이다. 기존의 단일모드 광도파로의 폭은 수 $mu extrm{m}$ 정도임에 비하여, 광 결정을 이용한 단일 결함 도파로인 경우 그 폭은 보통 1$\mu\textrm{m}$ 이하이다. 또한 광결정 도파로의 광 가둠 효과가 우수하여 기존 도파로와의 결합 사이에 모드 부정합 현상이 발생하며, 이것은 광결정 도파로의 광결합 효율은 낮게 하는 요인이 된다. (중략)

• Journal of Information Display
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• v.5 no.1
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• pp.7-15
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• 2004

A highly simplified backlight unit mainly composed of diffractive grating in sub-micron order imprinted light-guide plate (LGP) is proposed for edge-lit backlight unit. Optical characteristics of the imprinted LGP are examined by RCWA and the performance is verified through Monte Carlo simulation. Results show that the diffraction efficiency, luminous flux and its uniformity over the area are significantly affected by the angle of incident ray. Consequently couples of design considerations are additionally proposed to enhance luminous flux. In terms of peak luminance and out-coupling luminous flux, the experimental results are agreed well with the performance simulation. Finally, compared with optical characteristics of conventional backlight unit, we could conclude that the proposed simplified backlight unit made of diffractive grating imprinted light-guide plate is a good substitute for the conventional backlight unit.