• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.351-356
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• 2010

We investigated the combined effect of fiber chromatic dispersion and self-phase modulation (SPM) in multi-channel subcarrier multiplexed (SCM) optical transmission systems. We theoretically analyzed the transmission characteristics of the SCM signals with the effect of SPM and chromatic dispersion in a single-mode optical fiber by numerical simulations based on the nonlinear Schrodinger equation. The numerical simulation results revealed that the effect of fiber dispersion and SPM could occur independently between subcarrier channels in two-channel SCM systems for small optical modulation index (OMI) and large channel spacing. However, for large OMI, small channel spacing, and large fiber launching power, we found a performance degradation of the two-channel system compared to that of a single-channel system. These parameters are therefore important for the optimization of multi-channel SCM systems applicable to radio over fiber networks.

• Current Optics and Photonics
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• v.3 no.3
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• pp.227-235
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• 2019

With slimmer, lighter and all-reflective imaging systems in high demand for consumer and military applications, coaxially folded optical image systems are widely considered because they can extend focal length and reduce track length. Most of these systems consist of multiple surfaces, and these surfaces are machined on one element or grouping processing on two elements. In this paper, we report and first experimentally demonstrate an all-aluminum all-reflective optical system which consists of two optical elements, with two high order aspherical surfaces in each element. The coaxially folded system is designed with Seidel aberration theory and advanced optimization with Zemax. The system is made of all-aluminum material processing by single point diamond turning (SPDT). On this basis, we completed the system integration and performed an imaging experiment. The final system has the advantages of short track length and long focal length and broad application prospects in the micro-unmanned aerial vehicle field.

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.1-1
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• 1991

The fabrication of computer components requires a great variety of optical equipment. The patterning of integrated circuits is performed either on step-and-repeat cameras, scanning systems or step-and-repeat systems. The image forming optics used in these machines is quite difficult to design and fabricate. In addtion several layers of patterns must be precisely superposed, and also the illuminators have to provide the final irradiance in the image plane constant to within 1%. Other uses of specialized optical equipment are mass production of chip packages, inspection scanners and laser ablation cameras for polymers. The details of some of these systems will be described with particular ephasis on different optical structures and the use of excimer lasers as light sources.

• Transactions of the Society of Information Storage Systems
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• v.2 no.1
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• pp.79-84
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• 2006

The next generation of optical storage systems requires higher numerical aperture(NA) objective lenses and shorter wavelength laser in order to improve the unit areal density. A blu-ray technology satisfies a miniaturization and a high capacity which are the requirements of the portable device. In this paper, we analyze the optical performance of hybrid micro lens and do active alignment. The hybrid micro lens is manufactured by using a wafer based fabrication technology. Optical components of hybrid micro lens are evaluated. The measurement of the optical power, the spot size and the wavefront error are performed to evaluate the hybrid micro lens with NA 0.85. Using the measured data, we estimate if the performance of hybrid micro lens corresponds to the designed performance. After the performance of hybrid micro lens is evaluated. the integrated optical pickup and the hybrid micro lens are assembled by active alignment using UV curing and the optical performance of SFFOP is satisfied with BD specifications.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.1
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• pp.47-53
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• 1999

CD-ROM(Compact Disk-Read Only Memory) is very attractive storage media because it has much storage space but is small size and portable. Optical pickup, one of the most important parts for reading data on a CD-ROM, is not produced tuned up. For the use of goods, we must tune up the optical pickup by adjusting the screw for adjustment. First, we developed analog servo system for optical pickup tuners. For eliminating some problems in analog servo system, this paper designed the modeling of digital servo system for optical pickup tuner. Though the characteristics of optical pickup are changed, the digital servo system for optical pickup tuner can easily apply to all pickup, and can reduce the measurement error among the optical pickup tuners. For the purpose of confirming the designed digital servo system, we produced data that specify the disk vibration and the disk eccentricity, and simulated servo system with MATLAB.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.3
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• pp.251-258
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• 2003

Optical Switching Matrix (OSM) or Optical Multistage Interconnection Networks (OMINs) comprising photonic switches have been studied extensively as important interconnecting blocks for Optical Cross Connects (OXC) based on Optical Burst Switching (OBS). A basic element of photonic switching networks is a 2$\times$2 directional coupler with two inputs and two outputs. This paper is concerned with the diagnosis of multiple crosstalk-faults in OSM. As the network size becomes larger in these days, the conventional diagnosis methods based on tests and simulation become inefficient, or even more impractical. We propose a simple and easily implementable algorithm for detection and isolation of the multiple crosstalk-faults in OSM. Specifically. we develop an algorithm for isolation of the source fault in switching elements whenever the multiple crosstalk-faults arc detected in OSM. The proposed algorithm is illustrated by an example of 16$\times$16 OSM.

• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.546-549
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• 2006

In this paper the neuron operation based on Brillouin-active fiber in optical fiber is described. The inherent optical feedback by the backscattered stokes wave in optical fiber leads to instabilities in the form of optical chaos. Controlling of chaos induced transient instability in Brillouin-active fiber is implemented with Kerr nonlinearity having a non-instantaneous response in network systems. The controlling chaotic instabilities can lead to multistable periodic states; create optical logic 'on' or high level '1' or 'off', or low level '0'. It is theoretically possible to apply the multi-stability regimes as an optical memory device for encoding and decoding series and complex data transmission in optical systems.

• Journal of the Optical Society of Korea
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• v.9 no.1
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• pp.1-5
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• 2005

Using tightly focused femtosecond laser pulses, we produce an optical waveguide and optical devices in transparent materials. This technique has the potential to generate not only channel waveguides, but also three-dimensional optical devices. In this paper, an optical splitter and U-grooves, which are used for fiber alignment, are simultaneously fabricated in a fused silica glass using near-IR femtosecond laser pulses. The fiber aligned optical splitter has a low insertion loss, less than 4㏈, including an intrinsic splitting loss of 3㏈ and excess loss due to the passive alignment of a single-mode fiber. Finally, we demonstrate the utility of the femtosecond laser writing technique by fabricating gratings at the surface and inside the silica glass.

• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.373-374
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• 2006

This paper physically demonstrates that our proposed method improves the Signal-to-Noise Ratio (SNR) of significantly increase the number of acceptable optical signals in PON(Passive Optical Network) systems. This method reduced Optical Beat Interference(OBI) by using CDMA.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.355-356
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• 2009