• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.173-173
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• 2000

Multilayered films (MLF) consisting of transition metals and semiconductors have drawn a great deal of interest because of their unique properties and potential technological applications. Fe/Si MLF are a particular topic of research due to their interesting antiferromagnetic coupling behavior. although a number of experimental works have been done to understand the mechanism of the interlayer coupling in this system, the results are controversial and it is not yet well understood how the formation of an iron silicide in the spacer layers affects the coupling. The interpretation of the coupling data had been hampered by the lack of knowledge about the intermixed iron silicide layer which has been variously hypothesized to be a metallic compound in the B2 structure or a semiconductor in the more complex B20 structure. It is well known that both magneto-optical (MO0 and optical properties of a metal depend strongly on their electronic structure that is also correlated with the atomic and chemical ordering. In order to understand the structure and physical properties of the interfacial regions, Fe/Si multilayers with very thin sublayers were investigated by the MO and optical spectroscopies. The Fe/si MLF were prepared by rf-sputtering onto glass substrates at room temperature with a totall thickness of about 100nm. The thicknesses of Fe and Si sublayers were varied from 0.3 to 0.8 nm. In order to understand the fully intermixed state, the MLF were also annealed at various temperatures. The structure and magnetic properties of Fe/Si MLF were investigated by x-ray diffraction and vibrating sample magnertometer, respectively. The MO and optical properties were measured at toom temperature in the 1.0-4.7 eV energy range. The results were analyzed in connection with the MO and optical properties of bulk and thin-film silicides with various structures and stoichiometries.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3277-3285
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• 1996

In this paper, w designed an opical power distribution device for application to an optical switching and an optical subscriber loop. We fabricated PSG thin film by LPCVD. Based on the measured index of fabricted thin film, rib-type waveguide was transformed to two-dimension by the effective index method and we simulated dispersion property to find asingle-mode condition. We found that the optimum design parameters of rib-type waveguide are:cladding layer of 3.mu.m, core layer of 3.mu.m, buffer layer of 10.mu.m, and core width of 4.mu.m. Each side of the guiding region was etched down to 4.mu.m to shape the core. We used these optimum parameters of the rib-type waveguide with branching angle of 0.5.deg. and simulted the Y-branch waveguide by the BPM simulation. Numerical loss in branching area was claculated to be 0.1581dB and equal to the total loss of the Y-branch. The loss of the fabricated Y-branch waveguide on PSG film ws 1.6dB at .lambda.=1.3.mu.m before annealing but was 1.2dB after annealing at 1000.deg. C for 10 minutes. Consequently, the loss of branching area from 3000.mu.m to 6000.mu.m in the z-direction was 0.8dB, and single-mode propagation was confirmed by measuring the near field pattern. For coupling the fabricated Y-branch waveguide with an optical fiber, we fabricated V-groove which was used as the upholder of optical fiber. An etching angle was 54.deg. and the width and depth of guiding groove was 150.mu.m, 70.mu.m, respectively. The optical fiber is inserted onto V-groove. Both the Y-branch and V-groove were connected through the index matching oil. Coupling loss after connecting Y-branch and the optical fiber on V-groove was 0.34dB and that after injecting index mateching oil was 0.14dB.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.7
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• pp.13-20
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• 2004

In order to set up the design of micro optical bench, optical coupling efficiencies of two sets of test benches are calculated. Simple linear connections of incoming and outgoing optical fibers with and without ball lenses are designed. Positional errors that are possible in actual fabrication processes we considered in the calculations and their tolerances are determined from -3 ㏈ conditions. For a simple fiber-to-fiber connection, the lateral misalignment should be limited to 2.7 um and tilt error 5.8o. In case of the fiber-to-fiber with ball lens, the working distance between fibers can be extended over 60 um. The optical coupling efficiency depends strongly on the positional errors of ball lenses along the optical axis, and it is also found that the lateral and vertical positional errors should be considered simultaneously in order to keep the high coupling efficiency.

• Korean Journal of Optics and Photonics
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• v.21 no.1
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• pp.26-32
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• 2010

Line lamps, which utilize leaky optical fibers based on periodic bending of plastic optical fibers, are proposed. The LED-optical fiber coupler, the key component of the line lamp, is designed and analyzed. The analysis by the Monte Carlo photon simulation method has shown that the optical coupling efficiency is affected rather sensitively by $\theta_w$, the slanting angle of the reflecting cup sidewall and $\rho_{ref}$, the reflectivity of the reflecting cup. The optical coupling efficiency of the coupler reaches the maximum when $\theta_w$ is about $60^{\circ}$, which is significantly larger than $\theta_w=45^{\circ}$, the typical sidewall slanting angle of the reflecting cup adopted in most LED lamps. When the reflectivity of the reflecting cup is above 0.8, the optical coupling efficiency is larger than 80%, which is the typical efficiency to be achieved in LD-optical fiber coupler.

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.372-373
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• 2004

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.8
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• pp.1257-1261
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• 1989

The propagation of electromagnetic waves in a photorefractive crystal is considered. The electromagnetic waves(i.e. TE waves and TM, waves) incident upon the crystal at any incident angle are coupled with reflected waves due to the Fresnel's reflectance in the photorefractive crystal. This coupling leads to a nonreciprocal optical transmissivity. About some incident angles, the optical transmissivity of TE and TM waves in regard to the coupling strength is investigated.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.966-969
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• 1999

Using modal transmission-line theory (MTLT), we evaluate the power coupling of optical directional coupler composed by two parallel guiding slabs. The numerical results reveal that maximum power transfer occurs at a novel wavelength λ$_{opt}$, in which the excitation ratio of supermodes at input boundary is equal to each other, and it is generally different from minimum gap λ$_{min}$.in/.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.126-130
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• 2003

The optical power transfer of TM modes in grating-assisted directional couplers (GADCs) with three-guiding channels is rigorously evaluated by defining a novel coupling efficiency amenable to the rigorous analytical solutions of modal transmission-line theory (MTLT). The results reveal that the incident power is sensitively partitioned through three output channels in terms of such grating parameters as the period, the duty cycle, and wavelength.

• Korean Journal of Optics and Photonics
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• v.11 no.2
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• pp.114-118
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• 2000

The paper presents the effects of outpLlt-coLLpling power and small SIgnal gain of a He-Se+ laser by discharge of either $^4He$ or $^3He$. A quartz plane-plate was installed to outpLlt-coLlple the laseI beam from the resonator in the eAperimental setup. The result shows tbat compared with those of ~He, tbe outPLlt-coupling power and small-signal gain of $^4He$ increase in the most of the lines. EspeCIally, the small-signal gain of $^3He$ for the strong lines (497.6 nm, 499.3 nm, 506.9 urn, 5176 nm, 522.8 mn, 530.5 nm) lies 25% higher than Ulat of 4He, and the output-coupling power doubles oubles

• Korean Journal of Optics and Photonics
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• v.16 no.6
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• pp.527-534
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• 2005

We investigate the pulsation characteristics in a multi-section DFB laser which is composed of one DFB section, phase tuning section, and gain section. Multi-section DFB lasers with anti-phase (AP) complex-coupled (CC) DFB structure show wide current ranges of gain and phase tuning sections fer stable pulsations compared to those with in-phase CC DFB structure or index-coupled DFB structure. For multi-section DFB lasers with AP CC DFB structure, the current range of a gain section for stable pulsations increases and the tuning range of the pulsation frequency increases as a coupling strength or a gain coupling coefficient increases Also, the tuning range using the phase variation in a phase tuning section increases. For a fixed coupling strength, the current ranges of gain and phase tuning sections for stable pulsations increase and the tuning range of the pulsation frequency increases as the length of a DFB section increases.