• Computational Structural Engineering
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• v.17 no.3
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• pp.53-56
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• 2004

• Proceedings of the Korean Magnestics Society Conference
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• 1994.03a
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• pp.74-75
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• 1994

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.731-736
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• 2017

In this paper, we report the fabrication of concave surface fiber tips for optical resonators. It was confirmed that the radius of curvature on fiber end can be controlled by introducing the hydrofluoric acid solution and the wavelength of $1.55{\mu}m$ laser which is absorbed well in the etchant to induce the photothermal effect. Using the microscope images, we observed the proposed concave fiber tip fabrication method is effective to make the controllable concave tips. We also observed changes in the size of the beam emitted from the tips with the various radius of curvature using the beam profiler. The authors believe that the proposed method will be applied to resonators for optical communications.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1522-1526
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• 2005

In this study, the fabrication of large area silicon mirror is accomplished by anisotropic etching using MEMS for implementation of integrated optical pickup and the process condition is also established for improving the mirror surface roughness. Until now, few results have been reported about the production of highly stepped $9.74^{\circ}$ off-axis-cut silicon wafer using wet etching. In addition rough surface of the mirror is achieved in case of long etching time. Hence a novel method called magnetorheolocal finishing is introduced to enhancing the surface quality of the mirror plane. Finally, areal peak to valley surface roughness of mirror plane is reduced about 100nm in large area of $mm^2$ and it is applicable to optical pickup using infrared wavelength.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.351-356
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• 1995

A optical switch which on the LiNbO$_3$substrate is fabricated by using proton exchange method and self-alignet method. The annealing at 400[$^{\circ}C$] was carried out to control waveguide width and depth. A self-aligned method, which doesn\`t need the additional mask precesses, was applied to simplify the fabrication processes and to maximize efficiency of electric field application. The depths of the two annealed optical waveguides, which were measured by using ${\alpha}$-step, ware 1.435[K${\AA}$] and 1,380[K${\AA}$]. Using ${\alpha}$-step facility, we examined that the width of waveguides is increased from 5[$\mu\textrm{m}$] to 6.45[$\mu\textrm{m}$] and 6.3[$\mu\textrm{m}$] due to the annealing effects. The process of proton exchange was done at 400[$^{\circ}C$] for 60[min] and annealing process was done at 400[$^{\circ}C$] for 60[min]. The high speed optical modulator has very good figures of merits: the measured voltage of the input waveguide power is 3.5[V], the voltage of the coupling waveguide power is 3.9[mV], and -29.5[dB] crosstalk and 8[V] switching voltage were achieved.

• Journal of the Optical Society of Korea
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• v.15 no.4
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• pp.394-397
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• 2011

For the purpose of fabricating off-axis aspheric optics, we propose an 8-axis-polishing machine combined with a testing tower whose height is up to 9 m. The proposed polishing machine was designed and analyzed by using a well-known finite element method. The eight axes of the machine have a synchronized motion generated by a computer, and each axis was calibrated by a heterodyne laser interferometer or an optical encoder. After calibration, the maximum positioning error of the machine was less than 2 ${\mu}m$ within a whole 2 m ${\times}$ 2 m area. A typical fabrication result of a ${\phi}1.5$ m concave mirror was also described in this manuscript.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.865-868
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• 2001

We designed and fabricated a planner-type thermoelastic microactuator with a latch-up operation for optical switching. Latch-up actuation is prerequisite to implement an optical switch with low power consumption and high reliability. The proposed microactuator consists of four cantilever-shaped thermal actuators, four displacement linkages, two shallow arch-shaped leaf springs, a mobile shuttle mass with a micromirror, and four elastic boundaries. The structural layer of the planar microactuator is phosphorous-doped 12$\mu\textrm{m}$-thick polysilicon, and the sacrificial layer is LTO(Low Temperature Oxide) of 3$\mu\textrm{m}$thickness. The displacement of actuator is as large as 3$\mu\textrm{m}$when the length of actuation bar is 100$\mu\textrm{m}$in length at 5V input voltage. The proposed microactuators have advantages of easy assembly with other optical component by way of fiber alignment in the substrate plane, and its fabrication process features simplicity while retaining batch-fabrication economy.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.25-32
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• 2017

In this paper, a fabrication method of low-loss tapered optical fibers coupler using hydrofluoric acid with surface tension driven is proposed. The proposed fabrication method is very simple compared to flame-based method, and shows low excess insertion losses compared to polishing method. The adiabatic-tapered structure along the coupling region of the coupler shows wavelength independent characteristic over the C-band in optical communication system, and will enable promising applications.

• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.250-253
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• 2015

High contrast grating (HCG) is the structure made up of the sub-wavelength grating of high-index and the surrounding layer of low-index, which reveals high contrast between two materials. Its advantages include high reflectivity over a broad bandwidth, polarization and wavelength selectivity, optical high-Q resonator, and phase modulation. In this work, the HCG structure comprising of indium tin oxide (ITO) and Silicon (Si), for the surrounding layer and the grating layer respectively, was studied. Its theoretical model was established, and transmittance, phase and optical behavior were calculated by rigorous coupled-wave analysis and finite element method. Furthermore, the established structure was fabricated to validate its feasibility. The fabricated structure shows the focusing capability whose length is about $10{\mu}m$, and the feasibility of the structure was demonstrated. It is also meaningful that ITO layer can contribute to the fabrication of the HCG structure, leading to enable the structure to be electrical-driven.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.6
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• pp.88-97
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• 1994

We describe the design, fabrication, and performance of the optical fiber-photodiode 1$\times$12 arry module using mesa-type InS10.53T GaS10.47TAS/INP 1$\times$12 PIN photodiode array. We fabricated the PIN PD array for high-speed optical fiber parallel data link optimizing quantum efficiency, operating speed sensitivity from the PIN-FET structure, and electrical AC crosstalk. For each element of the array, the diameter of the photodetective area is 80 $\mu$m, the diameter of the p-metal pad is 90 $\mu$m, and the photodiode seperation is 250 $\mu$m to use Si v-groove. Ground conductor line is placed around diodes and p-metal pads are formed in zigzag to reduce Ac capacitance coupling between array elements. The dark current (IS1dT) is I nA and the capacitance(CS1pDT) is 0.9 pF at -5 V. No signifcant variations of IS1dT and CPD from element to element in the array were observed. We calulated the coupling efficiency for 10/125 SMF and 50/125 GI MMF, and measured the responsivity of the PD array at the wavelength is 1.55 $\mu$ m. Responsivities are 0.93 A/W for SMF and 0.96 A/W for MMF. The optical fiber-PD array module is useful in numerous high speed digital and analog photonic system applications.