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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Optical Society of Korea
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Journal DOI :
Optical Society of Korea
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Volume & Issues
Volume 15, Issue 4 - Dec 2011
Volume 15, Issue 3 - Sep 2011
Volume 15, Issue 2 - Jun 2011
Volume 15, Issue 1 - Mar 2011
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Complex Conjugate Resolved Retinal Imaging by One-micrometer Spectral Domain Optical Coherence Tomography Using an Electro-optical Phase Modulator
Fabritius, Tapio E.J. ; Makita, Shuichi ; Yamanari, Masahiro ; Myllyla, Risto A. ; Yasuno, Yoshiaki ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 111~117
DOI : 10.3807/JOSK.2011.15.2.111
Full-range spectral domain optical coherence tomography (SD-OCT) with a 1-
band light source is shown here. The phase of the reference beam is continuously stepped while the probing beam scans the sample laterally (B-scan). The two dimensional spectral interferogram obtained is processed by a Fourier transform method to obtain a complex spectrum leading to a full-range OCT image. A detailed mathematical explanation of the complex conjugate resolving method utilized is provided. The system's measurement speed was 7.96 kHz, the measured axial resolution was
in air and the maximum sensitivity 99.4 dB. To demonstrate the effect of mirror image elimination, In vivo human eye pathology was measured.
Analysis of a Triangular-shaped Plasmonic Metal-Insulator-Metal Bragg Grating Waveguide
Jafarian, Behnaz ; Nozhat, Najmeh ; Granpayeh, Nosrat ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 118~123
DOI : 10.3807/JOSK.2011.15.2.118
A novel triangular-shaped plasmonic metal-insulator-metal (MIM) Bragg grating waveguide is introduced, whose band-gap is narrower than that of the conventional step type and wider than that of the sawtoothshaped one. Moreover apodized triangular-shaped MIM Bragg grating structures are proposed in order to reduce the side lobes of the transmission spectrum, because the Bragg reflector with a sawtooth profile has a smoother transmission spectrum than that of a triangular-shaped one. The performance of the proposed structures is simulated by using the finite difference time domain method.
Design and Simulation of an 808 nm InAlAs/AlGaAs GRIN-SCH Quantum Dot Laser Diode
Chan, Trevor ; Son, Sung-Hun ; Kim, Kyoung-Chan ; Kim, Tae-Geun ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 124~127
DOI : 10.3807/JOSK.2011.15.2.124
Quantum dots were designed within a GRIN-SCH(Graded index - Separate confinement Heterostructure) heterostructure to create a high power InAlAs/AlGaAs laser diode. 808 nm light emission was with a quantum dot composition of In0.665Al0.335As and wetting layer composition of Al0.2Ga0.8As by LASTIP simulation software. Typical characteristics of GRIN structures such as high confinement ratios and Gaussian beam profiles were shown to still apply when quantum dots are used as the active media. With a dot density of 1.0x1011 dots/cm2, two quantum dot layers were found to be good enough for low threshold, high-power laser applications.
Extension of the Rotating Planar Waveguide Model to Formation of Interference Patterns in Optical Fibers
Pena-Garcia, Antonio ; Perez-Ocon, Francisco ; Jimenez, Jose Ramon ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 128~131
DOI : 10.3807/JOSK.2011.15.2.128
After the successful extension of the rotating planar waveguide model to Wave Optics, where a clear identification between the angular velocity of one hypothetical waveguide and the phase differences between two points on the path of one bounded mode was found, an application of the model to explain the interference theory is presented. We demonstrate that, for two bounded modes to create an interference pattern, a constrain to the relative parameters among both is imposed by the fiber optics. This result, not reported in the literature up to date, provides a new horizon to understand the interaction light-light when propagated within optical fibers.
Generalized Analysis on the Combined Effect of SPM and Fiber Chromatic Dispersion on Subcarrier Multiplexed Optical Transmission Systems for RoF Applications
Kim, Kyoung-Soo ; Lee, Jae-Hoon ; Jeong, Ji-Chai ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 132~139
DOI : 10.3807/JOSK.2011.15.2.132
We investigate theoretically the combined effect of fiber chromatic dispersion and self-phase modulation (SPM) on multi-channel subcarrier multiplexed (SCM) optical transmission systems in terms of the detected RF carrier power and SPM-induced power gain after transmission over single-mode fiber (SMF) links. According to the calculated power gain due to the SPM effect at the transmission distance of P3dB using the detected radio-frequency (RF) carrier power after photo-detection, the power gain is significantly degraded with large optical modulation index (OMI), small SCM channel spacing, and large fiber launching power because of the increased interaction between subcarrier channels. The nonlinear phase shift due to linear and nonlinear fiber characteristics is investigated to explain these results in detail. The numerical simulation results show that the OMI per SCM channel has to be smaller than 10 % for the fiber launching power of 10 dBm to guarantee prevention of SPM-induced power gain degradation below 0.5 dB for the SCM system with the channel spacing of 100 MHz. This result is expected to be utilized for the optical transmission systems using the SCM technology in future radio-over-fiber (RoF) networks.
Color Pattern Recognition with Recombined Single Input Channel Joint Transform Correlator
Jeong, Man-Ho ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 140~145
DOI : 10.3807/JOSK.2011.15.2.140
Joint transform correlator (JTC) is a well known tool for color pattern recognition for a color image. Color images have red, green and blue components, thus in conventional JTC, three input channels of these color components are necessary for color pattern recognition. This paper proposes a new technique of color pattern recognition by decomposing the color image into three color components and recombining those components into a single gray image in the input plane. This new technique needs single input channel and single output CCD camera, thus a simple JTC can be used. We present various kinds of simulated results to show that our newly proposed technique can accurately recognize and discriminate color differences.
Precise Test Sieves Calibration Method Based on Off-axis Digital Holography
Abdelsalam, Dahi Ghareab ; Baek, Byung-Joon ; Kim, Dae-Suk ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 146~151
DOI : 10.3807/JOSK.2011.15.2.146
We describe, throughout a Mach-Zehnder interferometric configuration, a new test sieves calibration method based on off-axis digital holography. The experiment is conducted on a test sieve of square openings. The nominal sieve opening is 1.00 mm with maximum individual opening of 1.14 mm in size. The recorded off-axis hologram is numerically processed using Fresnel transforms to obtain an object wave (amplitude and phase). From the reconstructed phase, the average size of the illuminated openings has been measured precisely. The proposed method can provide a real time solution for calibrating test sieves very precisely and with moderate accuracy.
Region-based Corner Detection by Radial Projection
Lee, Dae-Ho ; Lee, Seung-Gwan ; Choi, Jin-Hyuk ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 152~154
DOI : 10.3807/JOSK.2011.15.2.152
We propose a novel method which detects convex and concave corners using radial projection. The sum of two neighbors' differences at the local maxima or minima of the radial projection is compared with the angle threshold for detecting corners. In addition, the use of oriented bounding box trees and partial circles makes it possible to detect the corners of complex shapes. The experimental results show that the proposed method can separately detect the convex and concave corners, and that this method is scale invariant.
Terahertz Pulse Imaging of Micro-metastatic Lymph Nodes in Early-stage Cervical Cancer Patients
Jung, Eun-A ; Lim, Mee-Hyun ; Moon, Ki-Won ; Do, Young-Woong ; Lee, Soon-Sung ; Han, Hae-Wook ; Choi, Hyuck-Jae ; Cho, Kyoung-Sik ; Kim, Kyu-Rae ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 155~160
DOI : 10.3807/JOSK.2011.15.2.155
Lymph node metastasis is an important prognostic factor in cervical cancer patients. We report THz imaging for detecting micro-metastatic foci in the lymph nodes of early-stage uterine cervical cancer patients. Five paraffin-embedded metastatic lymph nodes from two cervical cancer patients were imaged using a THz time-domain spectroscopy system in the reflection mode. The size and shape of the tumor regions were compared with those from histopathologic examinations. The metastatic portions of lymph nodes as small as 3 mm were well delineated by THz imaging. The reflected peak amplitudes were lower in metastatic portions than in the normal portions of lymph nodes, and the difference in their peak-to-peak amplitudes was ~5%.
Retardation Free In-plane Switching Liquid Crystal Display with High Speed and Wide-view Angle
Kang, Wan-Seok ; Moon, Je-Wook ; Lee, Gi-Dong ; Lee, Seung-Hee ; Lee, Joun-Ho ; Kim, Byeong-Koo ; Choi, Hyun-Chul ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 161~167
DOI : 10.3807/JOSK.2011.15.2.161
In this paper, we propose an in-plane switching (IPS) mode for liquid crystal displays (LCDs) that, in principle, is free of retardation of the LC cell. Basically, the optical configuration of the LC cell consists of an A-plate and an LC layer for switching between the dark and bright states. We could achieve a fast response time compared with the conventional in-plane LC cell because the free retardation condition of the proposed LC cell enables us to reduce the cell gap even by quarter-wave retardation without any change of the optimized LC material in the transmissive mode. Experiments for verification of the proposed in-plane switching LC cells have shown a significant reduction of the rising time and falling time simultaneously due to the small cell gap. Furthermore, we also proposed an optical configuration for wide viewing property of the retardation free IPS LCD by applying the optical films. We proved the wide-view property of the retardation free IPS LCD by comparing its optical luminance with the calculated optical property of the conventional IPS LCD.
Characterization of IPS-LCD by Reduced One-dimensional Model
Park, Byung-Hee ; Lee, Yeon-Ho ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 168~173
DOI : 10.3807/JOSK.2011.15.2.168
Based on the distinctive characteristics observed in the intensity transmittance of an IPS-LC panel, the previous one-dimensional model is greatly reduced such that only a few data points and their interpolations predict the intensity transmittance of an IPS-LCD with a small error for arbitrary gray levels. Experimental procedure and numerical methods are described in detail.
Imaging Performance Analysis of an EO/IR Dual Band Airborne Camera
Lee, Jun-Ho ; Jung, Yong-Suk ; Ryoo, Seung-Yeol ; Kim, Young-Ju ; Park, Byong-Ug ; Kim, Hyun-Jung ; Youn, Sung-Kie ; Park, Kwang-Woo ; Lee, Haeng-Bok ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 174~181
DOI : 10.3807/JOSK.2011.15.2.174
An airborne sensor is developed for remote sensing on an aerial vehicle (UV). The sensor is an optical payload for an eletro-optical/infrared (EO/IR) dual band camera that combines visible and IR imaging capabilities in a compact and lightweight package. It adopts a Ritchey-Chr
tien telescope for the common front end optics with several relay optics that divide and deliver EO and IR bands to a charge-coupled-device (CCD) and an IR detector, respectively. The EO/IR camera for dual bands is mounted on a two-axis gimbal that provides stabilized imaging and precision pointing in both the along and cross-track directions. We first investigate the mechanical deformations, displacements and stress of the EO/IR camera through finite element analysis (FEA) for five cases: three gravitational effects and two thermal conditions. For investigating gravitational effects, one gravitational acceleration (1 g) is given along each of the +x, +y and +z directions. The two thermal conditions are the overall temperature change to
and the temperature gradient across the primary mirror pupil from
. Optical performance, represented by the modulation transfer function (MTF), is then predicted by integrating the FEA results into optics design/analysis software. This analysis shows the IR channel can sustain imaging performance as good as designed, i.e., MTF 38% at 13 line-pairs-per-mm (lpm), with refocus capability. Similarly, the EO channel can keep the designed performance (MTF 73% at 27.3 lpm) except in the case of the overall temperature change, in which the EO channel experiences slight performance degradation (MTF 16% drop) for
overall temperate change.
Poling Quality Enhancement of PPLN Devices Using Negative Multiple Pulse Poling Method
Choi, Ju-Won ; Ro, Jung-Hoon ; Ko, Do-Kyeong ; Yu, Nan-Ei ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 182~186
DOI : 10.3807/JOSK.2011.15.2.182
A poling method using multiple negative voltage was introduced to fabricate periodically poled lithium niobate (PPLN) devices with quasi-phase matching (QPM) period of
by utilizing an real-time visualization system. We also performed variation of the electric field during the poling. Two different conventionally used poling method, negative and positive single pulses, were used and the poling quality compared through microscopic images and far-field diffraction pattern analysis. Etched images on the +z and -z surfaces of PPLN showed that negative multiple pulse poling presented the highest periodicity in domain structures among the three methods. Duty ratio and its standard deviation were measured by analyzing far-field diffraction patterns. The newly introduced method of negative multiple pulse poling had duty ratio of 0.42 which was close to the ideal value of 0.50 and standard deviation of 0.020 that was about 3 times smaller than that of the other conventional methods.
Directional Emission from Photonic Crystal Waveguide Output by Terminating with CROW and Employing the PSO Algorithm
Bozorgi, Mahdieh ; Granpayeh, Nosrat ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 187~195
DOI : 10.3807/JOSK.2011.15.2.187
We have designed two photonic crystal waveguide (PCW) structures with output focused beams in order to achieve more coupling between photonic devices and decrease the mismatch losses in photonic integrated circuits. PCW with coupled resonator optical waveguide (CROW) termination has been optimized by both one dimensional (1D) and seven dimensional (7D) particle swarm optimization (PSO) algorithms by evaluating the fitness function by the finite difference time domain (FDTD) method. The 1D and 7D-optimizations caused the factors of 2.79 and 3.875 improvements in intensity of the main lobe compared to the non-optimized structure, whereas the FWHM in 7D-optimized structure was increased, unlike the 1D case. It has also been shown that the increment of focusing causes decrement of the bandwidth.
Near-field Characterization on Light Emanated from Subwavelength Plasmonic Double Slit of Finite Length
Kim, Ki-Young ; Goncharenko, Anatoliy V. ; Hong, Jian-Shiung ; Chen, Kuan-Ren ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 196~201
DOI : 10.3807/JOSK.2011.15.2.196
Near-field properties of light emanated from a subwavelength double slit of finite length in a thin metal film, which is essential for understanding fundamental physical mechanisms for near-field optical beam manipulations and various potential nanophotonic device applications, is investigated by using a three-dimensional finite-difference time-domain method. Near-field intensity distribution along the propagation direction of light after passing through the slit has been obtained from the phase relation of transverse electric and magnetic fields and the wave impedance. It is found that the near field of emerged light from the both slits is evanescent, that is consistent with conventional surface plasmon localization near the metal surface. Due to the finite of the slit, the amplitude of this evanescent field does not monotonically approach to than of the infinite slit as the slit length increases, i.e. the near-field of the longer slit along the center line can be weaker than that of the shorter one.
Design of Tunable Flat-top Bandpass Filter Based on Two Long-period Fiber Gratings and Core Mode Blocker
Bae, Jin-Ho ; Bae, Jun-Kye ; Lee, Sang-Bae ;
Journal of the Optical Society of Korea, volume 15, issue 2, 2011, Pages 202~206
DOI : 10.3807/JOSK.2011.15.2.202
We propose a tunable flat-top bandpass filter to pass light in a customized wavelength band by using long-period fiber gratings (LPFG) structure. The LPFG structure is composed of a core mode blocker in between two LPFGs. The bandpass spectrum of the proposed structure is obtained in overlapped wavelength band of two LPFGs operating on the same modes. To analyze the properties, we introduce a mathematical matrix model for the structure. We theoretically demonstrate flexibility of the flat-top bandpass filter with various bandwidths.