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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Optical Society of Korea
Journal Basic Information
Journal DOI :
Optical Society of Korea
Editor in Chief :
Shin, Jung Hoon
Volume & Issues
Volume 19, Issue 6 - Dec 2015
Volume 19, Issue 5 - Oct 2015
Volume 19, Issue 4 - Aug 2015
Volume 19, Issue 3 - Jun 2015
Volume 19, Issue 2 - Apr 2015
Volume 19, Issue 1 - Feb 2015
Selecting the target year
Analysis of Ni/Cu Metallization to Investigate an Adhesive Front Contact for Crystalline-Silicon Solar Cells
Lee, Sang Hee ; Rehman, Atteq ur ; Shin, Eun Gu ; Lee, Doo Won ; Lee, Soo Hong ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 217~221
DOI : 10.3807/JOSK.2015.19.3.217
Developing a metallization that has low cost and high efficiency is essential in solar-cell industries, to replace expensive silver-based metallization. Ni/Cu two-step metallization is one way to reduce the cost of solar cells, because the price of copper is about 100 times less than that of silver. Alkaline electroless plating was used for depositing nickel seed layers on the front electrode area. Prior to the nickel deposition process, 2% HF solution was used to remove native oxide, which disturbs uniform nickel plating. In the subsequent step, a nickel sintering process was carried out in
gas atmosphere; however, copper was plated by light-induced plating (LIP). Plated nickel has different properties under different bath conditions because nickel electroless plating is a completely chemical process. In this paper, plating bath conditions such as pH and temperature were varied, and the metal layer's structure was analyzed to investigate the adhesion of Ni/Cu metallization. Average adhesion values in the range of 0.2-0.49 N/mm were achieved for samples with no nickel sintering process.
All-Optical Binary Full Adder Using Logic Operations Based on the Nonlinear Properties of a Semiconductor Optical Amplifier
Kaur, Sanmukh ; Kaler, Rajinder-Singh ; Kamal, Tara-Singh ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 222~227
DOI : 10.3807/JOSK.2015.19.3.222
We propose a new and potentially integrable scheme for the realization of an all-optical binary full adder employing two XOR gates, two AND gates, and one OR gate. The XOR gate is realized using a Mach-Zehnder interferometer (MZI) based on a semiconductor optical amplifier (SOA). The AND and OR gates are based on the nonlinear properties of a semiconductor optical amplifier. The proposed scheme is driven by two input data streams and a carry bit from the previous less-significant bit order position. In our proposed design, we achieve extinction ratios for Sum and Carry output signals of 10 dB and 12 dB respectively. Successful operation of the system is demonstrated at 10 Gb/s with return-to-zero modulated signals.
In Vivo Measurement of Site-Specific Peritoneal Solute Transport Using a Fiber-Optic-based Fluorescence Photobleaching Technique
Lee, Donghee ; Kim, Jeong Chul ; Shin, Eunkyoung ; Ju, Kyung Don ; Oh, Kook-Hwan ; Kim, Hee Chan ; Kang, Eungtaek ; Kim, Jung Kyung ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 228~236
DOI : 10.3807/JOSK.2015.19.3.228
Fluorescence recovery after photobleaching (FRAP) is a well-established method commonly used to measure the diffusion of fluorescent solutes and biomolecules in living cells or tissues. Here a fiber-optic-based FRAP (f-FRAP) system was developed, and validated using macromolecules in water and agarose gels of different concentrations. We applied f-FRAP to measure the site-specific diffusion of fluorescein (NaFluo) in peritoneal membranes (PMs) on the liver, cecum, and kidney of a living rat during peritoneal dialysis. Diffusion of fluorescein in PM varied in a time-dependent manner according to the type of organ (
). The proposed method allows direct quantitative measurement of the three-dimensional diffusion in local PM in vivo, which was previously inaccessible by peritoneal function test methods such as peritoneal equilibration test (PET) and standardized PM assessment (SPA). f-FRAP is promising for local and dynamic assessments of peritoneal pathophysiology and the mass transport properties of PMs, presumed to be affected by variation of tissue structures over different organs and functional changes of the PM with years of peritoneal dialysis.
BER Analysis of Coherent Free Space Optical Systems with BPSK over Gamma-Gamma Channels
Lim, Wansu ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 237~240
DOI : 10.3807/JOSK.2015.19.3.237
We derived the average bit error rate (BER) of coherent free-space optical (FSO) systems with digital binary phase shift keying (BPSK) modulations over atmospheric turbulence channels with a gamma-gamma distribution. To obtain a generalized derivation in a closed-form expression, we used special integrals and transformations of the Meijer G function. Furthermore, we numerically analyzed and simulated the average BER behavior according to the average SNR for different turbulence strengths. Simulation results are demonstrated to confirm the analytical results.
Image Authentication Using Only Partial Phase Information from a Double-Random-Phase-Encrypted Image in the Fresnel Domain
Zheng, Jiecai ; Li, Xueqing ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 241~247
DOI : 10.3807/JOSK.2015.19.3.241
The double-random phase encryption (DRPE) algorithm is a robust technique for image encryption, due to its high speed and encoding a primary image to stationary white noise. Recently it was reported that DRPE in the Fresnel domain can achieve a better avalanche effect than that in Fourier domain, which means DRPE in the Fresnel domain is much safer, to some extent. Consequently, a method based on DRPE in the Fresnel domain would be a good choice. In this paper we present an image-authentication method which uses only partial phase information from a double-random-phase-encrypted image in the Fresnel domain. In this method, only part of the phase information of an image encrypted with DRPE in the Fresnel domain needs to be kept, while other information like amplitude values can be eliminated. Then, with the correct phase keys (we do not consider wavelength and distance as keys here) and a nonlinear correlation algorithm, the encrypted image can be authenticated. Experimental results demonstrate that the encrypted images can be successfully authenticated with this partial phase plus nonlinear correlation technique.
Computational Integral Imaging Reconstruction of a Partially Occluded Three-Dimensional Object Using an Image Inpainting Technique
Lee, Byung-Gook ; Ko, Bumseok ; Lee, Sukho ; Shin, Donghak ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 248~254
DOI : 10.3807/JOSK.2015.19.3.248
In this paper we propose an improved version of the computational integral imaging reconstruction (CIIR) for visualizing a partially occluded object by utilizing an image inpainting technique. In the proposed method the elemental images for a partially occluded three-dimensional (3D) object are recorded through the integral imaging pickup process. Next, the depth of occlusion within the elemental images is estimated using two different CIIR methods, and the weight mask pattern for occlusion is generated. After that, we apply our image inpainting technique to the recorded elemental images to fill in the occluding area with reliable data, using information from neighboring pixels. Finally, the inpainted elemental images for the occluded region are reconstructed using the CIIR process. To verify the validity of the proposed system, we carry out preliminary experiments in which faces are the objects. The experimental results reveal that the proposed system can dramatically improve the quality of a reconstructed CIIR image.
An Optical Pulse-Width Modulation Generator Using a Single-Mode Fabry-Pérot Laser Diode
Tran, Quoc-Hoai ; Nakarmi, Bikash ; Won, Yong Hyub ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 255~259
DOI : 10.3807/JOSK.2015.19.3.255
We have proposed and experimentally verified a pulse-width modulation (PWM) generator which directly generated a PWM signal in the optical domain. Output waveforms were clear at the repetition rate of 16 MHz; the duty cycle (DC) was from 14.7% to 72.1%; and the DC-control resolution was about 4.399%/dB. The PWM generator' operation principle is based on the injection-locking property of a single-mode Fabry-
laser diode (SMFP-LD). The SMFP-LD, which has a self-locked mode wavelength at
, was used to detect the power of the injection-locking signal (optical analog input). If the analog input power is high, the SMFP-LD is locked to the wavelength of the input signal
and there is no output after an optical bandpass filter (OBF). If the analog input power is low, the SMFP-LD is unlocked and there is output signal at
after the OBF. Thus, the SMFP-LD plus the OBF provide digital output for an analog input. The DC of the output PWM signal can be controlled by tuning the power of the analog input.
Negative Liquid Crystal Cell with Parallel Patterned Electrodes for High Transmittance and Fast Switching
Heo, Joon ; Choi, Tae-Hoon ; Huh, Jae-Won ; Yoon, Tae-Hoon ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 260~264
DOI : 10.3807/JOSK.2015.19.3.260
We propose a negative liquid crystal (n-LC) cell with parallel patterned electrodes for high transmittance and fast response. The proposed cell has higher transmittance and shorter response time than a conventional fringe-field switching cell using n-LCs, because the proposed cell does not have transmittance dips and does have a thinner LC layer.
Polarization-Dependent Microlens Array Using Reactive Mesogen Aligned by Top-Down Nanogrooves for Switchable Three-Dimensional Applications
Son, Ki-Beom ; Kim, Mugeon ; Park, Min-Kyu ; Kim, Hak-Rin ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 265~271
DOI : 10.3807/JOSK.2015.19.3.265
We propose a reactive mesogen (RM) lens array to obtain good focusing behavior along with a short focal plane, where the focusing behavior is switchable according to the polarization state of incident light. Polarization-dependent focusing behavior is obtained using a planoconvex RM microlens array on a planoconcave isotropic lens template. Even though the sagitta of our RM lens is high, to obtain the short focal length, the RM layer can be aligned well by introducing a top-down alignment effect, using a nanogrooved template. The optical noise due to the
effect generated by the nanogrooves on the surface of the planoconvex RM layer can be removed simply by overcoating a thin RM layer, which is self-aligned by the geometric surface effect, without an additional alignment process. We demonstrate a hexagonal-packed RM lens array that has a very high fill factor and symmetric phase profile, for an ideal lens.
Charge Transport Characterization of PbS Quantum Dot Solids for High Efficiency Solar Cells
Jeong, Young Jin ; Jang, Jihoon ; Song, Jung Hoon ; Choi, Hyekyoung ; Jeong, Sohee ; Baik, Seung Jae ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 272~276
DOI : 10.3807/JOSK.2015.19.3.272
The PbS quantum dot is an emerging photovoltaic material, which may provide high efficiency breakthroughs. The most crucial element for the high efficiency solar cells's development is to understand charge transport characteristics of PbS quantum dot solids, which are also important in planning strategic research. We have investigated charge transport characteristics of PbS quantum dot solids thin films using space charge limited conduction analysis and assessed thickness dependent photovoltaic performances. The extracted carrier drift mobility was
with the estimated diffusion length about 50 nm. These and recently reported values were compared with those from a commercial photovoltaic material, and we present an essential element in further development of PbS quantum dot solids materials.
Evaluation of Muscle Tension in Hemiplegia Patients with a Real-time Monitoring System during High Intensity Laser Therapy
Lee, Sang-Kwan ; Lee, Hyeong-O ; Youn, Jong-In ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 277~283
DOI : 10.3807/JOSK.2015.19.3.277
In this study, we evaluated the muscle tension in hemiplegia patients using a real-time monitoring system combined with high-intensity laser treatment (HILT) device. Five hemiplegia patients were treated with HILT in the left forearm muscle for 8 minutes, and the muscle was relaxed for 8 minutes following the treatment. Both the gradient of the force-displacement curves and the muscle hardness decreased during the therapy, and the effects were maintained following the treatment. The results show that muscle tension decreased rapidly during laser irradiation, and the efficacy of the treatment depended on the duration of the illness. Consequently, we conclude that this combined HILT and real-time muscle tension monitoring system is useful for evaluating the therapeutic procedure and for treatment of muscle pain.
Preliminary Study of Gender-Based Brain Lateralization Using Multi-Channel Near-Infrared Spectroscopy
V, Zephaniah Phillips ; Kim, Evgenii ; Kim, Jae Gwan ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 284~296
DOI : 10.3807/JOSK.2015.19.3.284
It has been thought that males tend to use their brain hemispheres more laterally than females. However, recent fMRI studies have shown that there may be no difference in brain lateralization between genders. Functional near-infrared spectroscopy (fNIRS) presents a unique opportunity to acquire real time measurements of blood oxygenation changes to observe neural activity specific to the brain's left and right hemispheres. Using an in-house built multichannel fNIRS system, brain lateralization was observed from seven males and four females according to specially designed tasks for left and right hemisphere activation. The Pearson correlation coefficient and a modified Lateralization Index metric for continuous wave fNIRS systems were calculated to quantify brain lateralization. The preliminary results point to no significant difference in lateral hemodynamic changes between the genders. However, the correlation of symmetrical channel pairs decreased as the experiments progressed. To further develop this study, the subject's performance and the removal of global interference must be implemented for an improved study of brain lateralization.
Investigation of Terahertz Generation from Bulk and Periodically Poled LiTaO
Crystal with a Cherenkov Phase Matching Scheme
Li, Zhongyang ; Bing, Pibin ; Yuan, Sheng ; Xu, Degang ; Yao, Jianquan ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 297~302
DOI : 10.3807/JOSK.2015.19.3.297
Terahertz (THz) wave generation from bulk and periodically poled
(PPLT) with a Cherenkov phase matching scheme is numerically investigated. It is shown that by using the crystal birefringence of bulk
and a grating vector of PPLT, THz waves can be efficiently generated by difference frequency generation (DFG) with a Cherenkov phase matching scheme. The frequency tuning characteristics of the THz wave via varying wavelength of difference frequency waves, phase matching angle, poling period of PPLT and working temperature are theoretically analyzed. The parametric gain coefficient in the low-loss limit and the absorption coefficient of the THz wave during the DFG process in the vicinity of polariton resonances are numerically analyzed. A THz wave can be efficiently generated by utilizing the giant second order nonlinearities of
in the vicinity of polariton resonances.
Development of Image-space Telecentric Lens for Intra-Oral 3D Scanner
Kim, Tae Young ; Shin, Min-Ho ; Chang, Ryungkee ; Kim, Young-Joo ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 303~310
DOI : 10.3807/JOSK.2015.19.3.303
An image-space telecentric lens for an intra-oral 3D scanner was designed and fabricated for dental application. Since a telecentric function can provide the same results regardless of image plane position, it helps to realize a more accurate image for an intra-oral scanner. The performance of the designed lens meets the required properties for HD resolution. In particular, lateral color is corrected within 1 pixel. This system achieves depth of focus of more than 3 mm. For user convenience, the developed system consists of a prism part and an imaging part. Both parts are optimized to reduce the front size and weight of the system. In order to make the parallax sights, parallax angle was determined to be 8 degrees between two optical systems.
Analysis of the Temperature Dependence of Phosphor Conversion Efficiency in White Light-Emitting Diodes
Ryu, Guen-Hwan ; Ryu, Han-Youl ;
Journal of the Optical Society of Korea, volume 19, issue 3, 2015, Pages 311~316
DOI : 10.3807/JOSK.2015.19.3.311
We investigate the temperature dependence of the phosphor conversion efficiency (PCE) of the phosphor material used in a white light-emitting diode (LED) consisting of a blue LED chip and yellow phosphor. The temperature dependence of the wall-plug efficiency (WPE) of the blue LED chip and the PCE of phosphor are separately determined by analyzing the measured spectrum of the white LED sample. As the ambient temperature increases from 20 to
, WPE and PCE decrease by about 4.5% and 6%, respectively, which means that the contribution of the phosphor to the thermal characteristics of white LEDs can be more important than that of the blue LED chip. When PCE is decomposed into the Stokes-shift efficiency and the phosphor quantum efficiency (QE), it is found that the Stokes-shift efficiency is only weakly dependent on temperature, while the QE decreases rapidly with temperature. From 20 to
the phosphor QE decreases by about 7% while the Stokes-shift efficiency changes by less than 1%.