• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.9 s.114
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• pp.971-981
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• 2006

This paper presents the design and characterization of a novel fiber optical coupler for intensity modulated fiber optical microphone. Theoretical equations for the optical power coupling are presented in detail including optical path analysis and misalignment. Various optical couplers are simulated and manufactured. A multi-mode to multi-mode coupler is characterized by static and dynamic movements of mirror on a well designed experimental stage.

• Journal of the Optical Society of Korea
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• v.20 no.3
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• pp.335-342
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• 2016

We demonstrate an optical asynchronous transfer mode/wavelength division multiplexing (OATM/WDM) optical access network, using a router based on an optical header decoder to conduct next-generation communications. The router consists of a decoder or hardware analysis processing of the header bit and switches. The router in the OATM/WDM optical access network is a key technology by which to satisfy subscribers’ requests, including reliability, cost efficiency, high speed, large-capacity transmission, and elevated information security. In this study, we carry out experiments in which a header decoder delivers to 16 and 32 subscribers with a single wavelength in the router. These experiments confirm the decoder’s successful operation via hardware using 4 and 5 header bits. We propose that this system may significantly contribute toward the realization of an optical access network that provides high-quality service to subscribers of next-generation communications.

• Korean Journal of Optics and Photonics
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• v.33 no.1
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• pp.35-44
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• 2022

Since optical systems are used for various applications, there are many designs, depending on the purpose and optical specifications, even though they have similar formations. Optical aberrations of a system are affected by both structure and specifications. Thus, it is very difficult to find the special characteristics of an optical design by using aberration analysis only. Regardless of specifications, a new method to investigate the aberration characteristics of an optical design is presented, using dimensionless design parameters. Four kinds of triplet designs with different applications and specifications are analyzed as examples.

• Current Optics and Photonics
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• v.8 no.1
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• pp.56-64
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• 2024

In response to the current situation where general methods cannot effectively compensate for the phase delay of ordinary optical mixers, a multi-layer spatial beam-splitting optical mixer is designed using total reflection triangular prisms and polarization beam splittings. The phase delay is generated by the wave plate, and the mixer can use the existing parallel plates in the structure to individually compensate for the phase of the four output beams. A mixer model is established based on the structure, and the influence of the position and orientation of the optical components on the phase delay is analyzed. The feasibility of the phase compensation method is simulated and analyzed. The results show that the mixer can effectively compensate for the four outputs of the optical mixer over a wide range. The mixer has a compact structure, good performance, and significant advantages in phase error control, production, and tuning, making it suitable for free-space coherent optical communication systems.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.484-487
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• 2004

Symmetric directional couplers are widely used in interferometers, switches, and various signal processing devices. Recently, several optical couplers using multimode fibers were reported, but these suffer from inefficient coupling of light into a branching fiber and/or low directivity. This paper presents the measurement and analysis of loss in the connection of optical fibers via the optical directional couplers. The functionality of the device is based on the principle that is symmetrical, the power in excited mode can be unambiguously directed into one of the output channel by varying and of its parameters. In this experiment, we measure the power of loss in the optical directional coupler at various radius of curvature. Before the measurement of loss in x-coupler, we polish the contact of the fiber surface in order that light can penetrate through another port. The results show that, when the radius of curvature is increased, the loss power is decreased and also approaches of the straight line case.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.8 no.4
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• pp.139-144
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• 1983

In this paper, the ploarization and Faraday rotation properties of the single mode optical fiber have been investigated for magnto-optic current transformer application. On the analysis, the optical fiber is modeled as a linear retarder and the intrinsic birefreingence of the optical fiber is approximately found to be 2.57'/m from the measurement, and the bend-induced birefringence is proportional to the inverse square of bending radius. The polarization rotation sensitivity is foung to be F/H=1.4x$10^-5$rad/[A/m] from the analysis of Faraday rotation of single mode optical fiber.

• Proceedings of the Optical Society of Korea Conference
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• 1998.08a
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• pp.220-221
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• 1998

An optical implementation of higher order neural networks based on based principal component analysis and time integration has been described. The principal component analysis combined with time integration allows larger input size than fully spatial neural networks at the cost certain amount of time consumption. This time-integration usage actually breaks down the barrier of the maximum space-bandwidth product that optical systems can offer.

• Journal of the Optical Society of Korea
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• v.20 no.4
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• pp.451-463
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• 2016

The misalignment errors and fluctuations in irradiance due to atmospheric turbulence can severely degrade the performance of free-space optical (FSO) systems. In this paper, we investigate the asymptotic bit error rate (BER) performance and diversity orders of FSO links using parallel transmit-diversity schemes. The BER expressions of FSO links with the switch-and-examine transmit (SET), switch-and-examine transmit with post-selection (SETps), dual-branch transmit laser selection (Dual-TLS), and group transmit laser selection (Group-TLS) schemes are derived, based on an approximate channel model. Then numerical simulations for these four schemes in the region of high average signal-to-noise ratio (SNR) are presented under different channel conditions. The results show that the four transmit-diversity schemes can reduce system complexity and overcome the limitation of peak power, without much BER deterioration.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.9
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• pp.661-667
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• 2002

With the increase of storage density, high rotational speed and high access technologies in optical disk drive, mechanical issues, mainly noise and vibration, become critical. Up to now the researches of rubber mount for anti-vibration focused on how to calculate the static and the dynamic stiffness of rubber mount and loaned out consideration of the dimensional tolerance of rubber mount for anti-vibration. This paper presents the effects of dimensional tolerance of rubber mount for anti-nitration on the dynamic characteristics of optical disk drive by finite element analysis and dynamic test. The relation between dimensional tolerance and dynamic characteristics of optical disk drive is observed and discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.755-761
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• 2003

Recently, the development of mobile devices demands information storage systems to use micro drive devices and cheap media. These should have several characteristics, for example, the subminiature of size, the robustness of shock, the minimum of cost and power consumption, and the removability of multiple applications. A conventional optical disk drive is more suitable for these specifications than the others. The optical storage system of the new generation to use a blue laser and a high numerical aperture (NA) is the perfect candidate for micro optical disk drives. In this paper, the micro actuator that can be applied to a micro optical disk drive is designed by response surface methodology to use a structural analysis and an electro-magnetic analysis. Based on above results, the coarse actuator and fine actuator are designed and improved from the point of view of the size and the power. Consequently, the designs of a micro actuator are proposed through these courses.