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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Korean Journal of Optics and Photonics
Journal Basic Information
Journal DOI :
Optical Society of Korea
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Volume & Issues
Volume 18, Issue 6 - Dec 2007
Volume 18, Issue 5 - Oct 2007
Volume 18, Issue 4 - Aug 2007
Volume 18, Issue 3 - Jun 2007
Volume 18, Issue 2 - Apr 2007
Volume 18, Issue 1 - Feb 2007
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Frequency Characteristic Estimation of Ceramic Stem based TO Package using a Coplanar Waveguide Feed-line for 10 Gbps Data Transmission
Yoon, Euy-Sik ; Lee, Myoung-Jin ; Jung, Ji-Chae ;
Korean Journal of Optics and Photonics, volume 18, issue 4, 2007, Pages 235~240
DOI : 10.3807/HKH.2007.18.4.235
A ceramic stem based TO package incorporating a coplanar waveguide feed-line has been proposed allowing for 10 Gbps grade data transmission. The frequency response of a cylindrical feed-line fer a conventional metal based TO package was first analyzed, and compared with that of the CPW feed-line used for a ceramic based package such as a butterfly package. For the case where a DFB LD chip is packaged to an LD module, the measured 3 dB frequency bandwidths for the conventional and proposed packages were 3.5 GHz and 7.8 GHz respectively, which agree well with the theoretical results obtained from the modeling based on the small signal equivalent circuits. Consequently, we proposed a novel ceramic based TO package with a CPW feed-line in ceramic material as a stem to improve the frequency characteristics of the conventional one. And, its performance was theoretically observed to confirm that the proposed package provides even wider frequency bandwidth compared to the conventional one.
Fabrication and Characterization of Two-dimensional Fiber-optic Radiation Sensor for High Energy Photon Beam Therapy Dosimetry
Jang, Kyoung-Won ; Cho, Dong-Hyun ; Shin, Sang-Hun ; Kim, Hyung-Shik ; Yi, Jeong-Han ; Lee, Bong-Soo ; Kim, Sin ; Cho, Hyo-Sung ;
Korean Journal of Optics and Photonics, volume 18, issue 4, 2007, Pages 241~245
DOI : 10.3807/HKH.2007.18.4.241
In this study, a two-dimensional fiber-optic radiation sensor has been developed using water-equivalent organic scintillators for photon beam therapy dosimetry. Two-dimensional photon beam distributions and percent depth doses(PDD) are measured according to the energies and field sizes of the photon beam. This sensor has many advantages such as high resolution, real-time measurement and ease of calibration over conventional radiation measurement devices.
A Study on Compensation of Disparity for Incorrect 3D Depth in the Triple Fresnel Lenses floating Image System
Lee, K.H. ; Kim, S.H. ; Yoon, Y.S. ; Kim, S.K. ;
Korean Journal of Optics and Photonics, volume 18, issue 4, 2007, Pages 246~255
DOI : 10.3807/HKH.2007.18.4.246
The floating image system (FIS) is a device to display input source in the space between fast surface of the display and an observer and it provides pseudo 3D depth to an observer when input source as real object or 2D image was displayed through the optical lens system in the FIS. The Advanced floating image system (AFIS) was designed to give more effective 3D depth than existing FIS by adding front and rear depth cues to the displayed stereogram, which it was used as input source. The magnitude of disparity and size of stereogram were strongly related each other and they have been optimized for presenting 3D depths in a non-optical lens systems. Thus, if they were used in optical lens system, they will have reduced or magnified parameters, leading to problem such as providing incorrect 3D depth cues to an observer. Although the size of stereogram and disparity were demagnified by total magnifying power of optical system, the viewing distance (VD) from the display to an observer and base distance (BD) for the gap between the eyes were fixed. For this reason, the quantity of disparity in displayed stereogram through the existing FIS has not kept the magnifying power to the total optical system. Therefore, we proposed the methods to provide correct 3D depth to an observer by compensating quantity of disparity in stereogram which was satisfied to keep total magnifying power of optical lenses system by AFIS. Consequently, the AFIS provides a good floating depth (pseudo 3D) with correct front and rear 3D depth cues to an observer.
Optical Design of Gradient-Index Objective for Optical Pickup
Park, In-Kyu ; Lee, Jong-Ung ;
Korean Journal of Optics and Photonics, volume 18, issue 4, 2007, Pages 256~263
DOI : 10.3807/HKH.2007.18.4.256
High NA objective design by using SELFOC materials was studied, and two kinds of objective for optical pick-up were designed. The SELFOC materials have radial gradient index distribution, and it gives additional degree of freedom in optical design. Therefore, we expect that optical design of high NA objective without aspheric surface will be possible. In this study, the variation of ms spot diameter was investigated as a function of quadratic constant and refractive index on axis for various combinations of axial thickness and entrance pupil diameter. For the survey, Code V was used for optimization and evaluation of the objective lenses. The result suggested that larger quadratic constant and higher refractive index on axis could give us better imaging performance for all combinations of axial thickness and pupil diameter. Based on the survey, we designed high NA objectives for DVR. There were two kinds of design solution consisting two spherical SELFOC lenses. The solution I had positive-positive lens configuration with short over-all-length, but it had poor off-axial performance compared with the solution II. The solution II had negative-positive lens configuration with good off-axial imaging performance. But the solution II had some disadvantages, long over-all-length and large diameter of the second lens.
Modeling and Analysis of Radiation Patterns of High Power LED Package for Luminarie
Cho, Jae-Moon ; Kim, Byung-Il ; Kwak, Joon-Seop ; Yoon, Dong-Joo ; Yu, Jin-Yeul ;
Korean Journal of Optics and Photonics, volume 18, issue 4, 2007, Pages 264~269
DOI : 10.3807/HKH.2007.18.4.264
Today`s research has been focused on changing the light source from filament to LED for luminarie illumination to overcome the shortcoming of a filament. The purpose of this research is to make an appropriate high power LED package structure for luminarie. We simulated radiation patterns of the various structures by the ray tracing simulator (Light Tools), and also analyzed the radiation patterns using an LED test system (OL770). As we increased an inner reflector angle, the radiation pattern split into two peaks and the angle between two peaks became larger. In addition, when we increased an outer reflector angle, the angle between side peaks gradually decreased, while it increased again when the angle reach
. These results could be understood from the ray tracing of the light reflected from two reflectors. We made the high power LED package for luminarie on the condition of the optimized structure which was made by ray tracing simulation results, and we measured the radiation patterns by using an LED test system, and these results were well matched to the simulation results.
Output Characteristics of the Longitudinally Pumped 946 nm Nd:YAG Laser with Laser Diode
Park, Cha-Gon ; Choo, Han-Tae ; Kim, Gyu-Ug ;
Korean Journal of Optics and Photonics, volume 18, issue 4, 2007, Pages 270~273
DOI : 10.3807/HKH.2007.18.4.270
We have investigated the output characteristics of the 946 nm Nd:YAG laser which is longitudinally pumped by a fiber coupled laser diode. The temperature of a Nd:YAG crystal mount was kept constant by a controller with thermoelectric cooler. As a result, we measured more intense output at a low temperature, and then the maximum output power was measured to be 870 mW when the pumping power and the temperature were 9.95 W and
, respectively. It appeared that output was decreased above 10 W pump power because of the thermal effects in gain medium.
Optical Coherence Tomography with Sinusoidal-Wave Drive an Optical Delay Line using Piezoelectrics Strecher
Kim, Young-Kwan ; Kim, Yong-Pyung ;
Korean Journal of Optics and Photonics, volume 18, issue 4, 2007, Pages 274~279
DOI : 10.3807/HKH.2007.18.4.274
We fabricated and characterized an optical delay line for optical coherence tomography (OCT). The delay line was composed of a cylindrical piezoelectric transduce (PZT) and a single mode optical fiber. The OCT system used a duplex scanning optical delay line which was symmetrically driven in the reference and sample arms. We showed that the sinusoidal-wave was superior to a triangular-wave for driving the optical delay line for scanning depth and repeatability.
Mode Size Converter based on Muitimode Fiber Taper
Kim, Kwang-Taek ; Park, Kiu-Ha ; Hyun, Woong-Keun ; Jung, Yong-Min ; Lee, Byeong-Ha ;
Korean Journal of Optics and Photonics, volume 18, issue 4, 2007, Pages 280~285
DOI : 10.3807/HKH.2007.18.4.280
Based on the multimode fiber taper, a mode size converter for effective optical beam coupling between laser and optical fiber or between the two different optical fibers has been proposed and demonstrated. The device has a multimode input end and a single mode output end. The influence of various parameters, including device structure and launching conditions, on the coupling efficiency has been theoretically analyzed. The theoretical results revealed that the gaussian beam can be coupled into a single mode fiber without considerable insertion loss. The proposed multimode fiber taper has been fabricated using heating and pulling equipment incorporating two micro-torches. Experimental results showed that an optical beam with
of large beam size was effectively coupled into single mode fiber through the multimode fiber taper. The insertion loss of the device was 1.3 dB.
Theoretical Calculation on Radiation Patterns of Epi-signal in CARS Microscopy
Yoo, Yong-Shim ; Cho, Hyuck ;
Korean Journal of Optics and Photonics, volume 18, issue 4, 2007, Pages 286~291
DOI : 10.3807/HKH.2007.18.4.286
We theoretically investigated the far-field radiation pattern of epi-signal from a polystyrene sphere in coherent anti-Stokes Raman scattering (CARS) microscopy with an objective lens of high numerical aperture. We calculated the field distribution of the incident laser beams under the tight-focusing condition and the far-field radiation pattern through coherent addition of radiation from the nonlinear polarizations (Hertzian dipoles) as the origin of CARS signal generation. The epi-radiation patterns for polystyrene spheres of different diameters are calculated, and the pattern of a sphere is also compared with that of a shell fer a diameter of 1100 nm. We finally show how the radiation pattern of the polystyrene sphere changes as the center of the sphere shifts from the focus of the beam.