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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
Editor in Chief :
Volume & Issues
Volume 17, Issue 6 - Dec 2006
Volume 17, Issue 5 - Oct 2006
Volume 17, Issue 4 - Apr 2006
Volume 17, Issue 2 - Apr 2006
Volume 17, Issue 3 - Mar 2006
Volume 17, Issue 1 - Feb 2006
Selecting the target year
A Study of Optical System Design for a Retinal Camera
Hong, Kyung-Hee ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 113~119
DOI : 10.3807/KJOP.2006.17.2.113
We need a good image of the retina of the human eye in order to inspect or cure it. In this work, an optical system design for a retinal camera is studied and the finite schematic eye model made by Sang Gee Kim and Sung Chan Park is used. The optical system is composed of four lens groups. The rays of the entire object field are collected on the center by the 1st group and the objective is imaged by all the other groups. The image is detected by the CCD array and displayed by a monitor The 1st lens group is employed singlet and other groups are employed triplets. Ray aberrations, spot diagrams, diffraction line spread functions and MTFs are calculated for optical performance assessment. This design may be very useful for the development of a retinal camera with high performance.
Novel Criterions to determine Optimized Power coupling in Grating-Assisted Fiber Couplers (GAFCs)
Ho, Kwang-Chun ; Ho, Kwang-Soo ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 120~126
DOI : 10.3807/KJOP.2006.17.2.120
A grating-assisted fiber coupler(GAFC), which consists of a thin-film waveguide with grating and circular optical fiber, is proposed and the optimized power coupling is evaluated by using a technique amenable to rigorous longitudinal modal transmission-line theory(L-MTLT). In addition, novel criteria to couple an optical signal incident through the grating waveguide to a single-mode optical fiber are proposed. The numerical result reveals that the optimized power coupling occurs at minimum-gap condition between rigorous modes rather than for the conventional phase-matching condition.
Simulation of Distributed Optical Fiber Sensors Using Spatially-Selective Brillouin Scattering
Yun, Seung-Chul ; Seo, Min-Sung ; Park, Hee-Gap ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 127~135
DOI : 10.3807/KJOP.2006.17.2.127
We implement numerical simulations for the distributed optical fiber sensor system that uses the spatially-selective Brillouin scattering, by treating the superposition of the optical-frequency-modulated pump/probe waves in the time domain. We obtain temporal and spatial distributions of Brillouin gain for various cases. Simulations are applied to the case of concatenated optical fibers of different kinds and the case of distributed temperature along the fiber, which give reasonable results for the distributed sensor. The result of using a triangular wave instead of a sinusoidal one as a modulation waveform shows that the triangular wave modulation has an advantage in spatial resolution.
Modeling of Transmitting Light Irradiance Distribution of Step-index Multimode Optical Fiber
Shin, Woo-Cheol ; Hong, Jun-Hee ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 136~142
DOI : 10.3807/KJOP.2006.17.2.136
This paper presents irradiance distribution model of light radiated from a step-index multimode optical fiber. The model is important in analysis of displacement response characteristics for intensity modulation type optical fiber sensors. The induced model was verified by experimental results. And the displacement response analysis result induced by using the irradiance distribution model was verified by experimental results and compared with using existing irradiance distribution models such as the constant model or the gaussian model. The experiment has better agreement with the analysis result using the induced model in this study than with the others models.
Measurement of Brillouin Gain Spectrum of Optical Fiber Using Direct Optical Frequency Modulation of Laser Diode
Seo, Min-Sung ; Yun, Seung-Chul ; Park, Hee-Gap ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 143~148
DOI : 10.3807/KJOP.2006.17.2.143
A new method of measuring the Brillouin gain spectrum of optical fiber is proposed and demonstrated. Unlike existing methods, both the pump light and the counter-propagating probe light are generated from a single laser diode whose optical frequency is directly modulated by injection current modulation. The frequency difference between the pump and the probe is scanned continuously through optical frequency chirp occurring when the injection current is modulated with a square wave. The measured Brillouin gain spectrum of telecom single-mode fiber agrees well with that shown in other literature.
Tolerance analysis of Multi-Configurative Microscopic System for Inspecting the Wire-Bonding Status of Semiconductor Chips
Ryu, Jae-Myung ; Kim, Jae-Bum ; Kang, Geon-Mo ; Jung, Jin-Ho ; Baek, Seung-Sun ; Jo, Jae-Heung ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 149~158
DOI : 10.3807/KJOP.2006.17.2.149
We have analyzed various tolerances of the multi-configurative microscopic system for inspecting the wire-bonding of a reed frame by using the Gaussian bracket method and the equivalent lens method. The tolerances for the curvature and the thickness, which are axial symmetric tolerances, are given by varying the back focal length within a fecal depth under diffraction-limited conditions. Moreover, by using the trial and error method, the axial non-symmetric tolerances for decenter and tilt are established by assigning the 5% variation of MTF(modulation transfer function) at the spatial frequency of 50 lp/mm and at the field angle of 0.7 field. As the tolerances with the most probable distribution are distributed within the range of the decay rate of less than 5% independent of the probability distribution of tolerances, we can achieve completely the desired design performances of the multi-configurative microscopic system by using the various ranges of these tolerances.
Fabrication of an On System based on an Optical Delay line with Cylindrical PZT
Park, Sung-Jin ; Kim, Young-Kwan ; Kim, Yong-Pyung ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 159~164
DOI : 10.3807/KJOP.2006.17.2.159
We demonstrate a compact optical coherence tomography(OCT) system based on the optical fiber delay line controlled by a cylindrical piezo-electric transducer(PZT). An 18-m length of single mode fiber is wrapped under constant tension around a PZT. Approximately 134 windings are used. Wraps of the long length of fiber allow the small expansion of the PZT to be magnified to an optical path length delay of 0.78 m. The OCT system shows characteristics for 2-dimensional imaging, exhibiting 96.9dB of signal-to-noise ratio(SNR),
of axial resolution, and
of lateral resolution with samples.
Fabrication Measurement and Evaluation of a Parabolic Mirror with the Diameter of 450 mm(f/2.7) by Autostigmatic Null Lens System
Lee, Young-Hun ; Jo, Jae-Heung ; Rim, Cheon-Seog ; Lee, Yun-Woo ; Yang, Ho-Soon ; Lee, Jae-Hyeob ; Lee, In-Won ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 165~174
DOI : 10.3807/KJOP.2006.17.2.165
The autotstigmatic null lens system is designed and constructed for the fabrication of a parabolic mirror with the diameter of 450 mm(f/2.7). And the measurement reliability is also analyzed theoretically by means of the tolerancing technique using lens design software(CODE V). From this analysis, we can precisely fabricate a parabolic mirror with the large diameter of 450 mm(f/2.7). Meanwhile, in order to confirm the fabrication results by the autostigmatic method, the mirror surface is tested again by an autocollimating method that uses only a plane mirror without any null lens.
Design and Fabrication of 5.5GHZ SSB optical modulator with polarization reversed structure
Jeong, W.J. ; Kim, W.K. ; Yang, W.S. ; Lee, H.M. ; Lee, H.Y. ; Kwon, S.W. ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 175~180
DOI : 10.3807/KJOP.2006.17.2.175
A single sideband(SSB) modulator operating at 5.5 GHz was fabricated by polarization inversion techniques. The dimension of domain inversion in a
Mach-Zehnder structure was precisely controlled so that the RF signal applied on two Mach-Zehnder arms gives rise to
effective phase difference. The single sideband suppression was maximized by optimization of the polarization status of the optical input and by the DC bias value. The fabricated device showed the center frequency of 5.8 GHz and the maximum sideband suppression of 33dB, where the bandwidth of 15 dB sideband suppression ranged over a 2.5 GHz span. The optical phase delay could be regulated by the DC bias voltage, fur example, the enhanced optical modulation sideband was distinctively switched from the upper sideband to the lower sideband by changing the DC bias voltage from 1.9 V to -10.6 V.
60 GHz Optical Carrier Generator using Quasi-Velocity-Matching Technique
Kim, W.K. ; Yang, W.S. ; Lee, H.M. ; Lee, H.Y. ; Jeong, W.J. ; Kwon, S.W. ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 181~185
DOI : 10.3807/KJOP.2006.17.2.181
A novel 60GHz optical carrier generator with a polarization domain-inverted structure is suggested and is demonstrated. The two arms of the Mach-Zehnder optical waveguide are periodically poled for quasi-phase velocity matching between the optical wave at 1550nm and the RF wave at 30 GHz. The center frequency of band-pass modulation and the 3 dB bandwidth of the fabricated modulator were measured to be 30.3 GHz and 5.1 GHz, respectively. Sub-carriers with the frequency difference of 60GHz waeregenerated under appropriate DC biac voltage application while the carrier was suppressed to lead to the power ratio between the modulated sub-carrier and the suppressed fundamental carrier of 28 dB, which proves that double sideband- suppressed carrier(DSB-SC) operation can be realized by the suggested single device.
Design of null lens for Alignment of the Unstable Laser Resonator
Kim, Hyun-Sook ; Kim, Yeon-Soo ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 186~190
DOI : 10.3807/KJOP.2006.17.2.186
The use of null optics is proposed as a new concept for the precise alignment of a confocal unstable resonator. The characteristics of the proposed null optics are investigated and analysed with the designed null lens for a real confocal unstable resonator of which the length is 3.5 m. As a result of the analysis, the pupil map data are shown about the despace error of 1.0 mm and tilt error of 1.0 mrad.
A Multi-Section Complex-Coupled DFB Laser with a Very Wide Range of Self-Pulsation Frequency and High Modulation Index
Kim, Boo-Gyoun ; Kim, Tae-Young ; Kim, Sang-Taek ; Kim, Sun-Ho ; Park, Kyung-Hyun ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 191~197
DOI : 10.3807/KJOP.2006.17.2.191
We analyze the self-pulsation(SP) characteristics due to mode beating of two modes emitted in a multi-section complex-coupled (CC) DFB laser composed of two DFB sections and a phase control section between them. SP frequency due to mode beating of the two modes is determined by the difference of grating periods in the two CC DFB regions. As the difference of grating periods in the two CC DFB regions increases, the SP frequency increases from very low frequency to the THz region. In the case of a mode which is not located in the stop band of the other DFB region, the mode propagates into the other DFB region without a high reflection, so that output powers emitted in a multi-section CC DFB laser have high modulation indexes due to the large interaction between the two modes.
Output characteristic analysis of the symmetric Nd:YAG laser consisted of two laser rods with rod-end curvatures
Kim, Hyun-Su ; Lee, Sung-Man ; Rhee, Young-Joo ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 198~202
DOI : 10.3807/KJOP.2006.17.2.198
Resonator stability condition,
beam quality factor, and laser output power are analyzed for two types of two-rod Nd:YAC lasers with rod-end curvatures. Two laser rods with rod-end curvatures are positioned closely to each other or placed separately near each resonator mirror. Experimentally, the output powers and
beam quality factors of those lasers are measured with and without thermal birefringence compensation, and compared to numerical analyses.
Formation of nano-pattern on metal using femtosecond laser pulses
Choi, Sung-Chul ; Lee, Yeung-Lak ; Noh, Young-Chul ; Lee, Jong-Min ; Ko, Do-Kyeong ; Lee, Jung-Hoon ; Kim, Kang-Yoon ; Kim, Chang-Jong ; Lee, Ung-Sang ; Heo, Myeong-Koo ;
Korean Journal of Optics and Photonics, volume 17, issue 2, 2006, Pages 203~206
DOI : 10.3807/KJOP.2006.17.2.203
Femtosecond laser-induced nano-patterning of an Al surface coated on a slide glass is reported in this paper. It was found that the period of the laser-induced nano-patterning was much dependent on the incident laser power and pulse number. Through finely adjusting the laser power and pulse number, uniform nano-patterns could be formed on the Al surface. It is based on the interference of the incident laser beam with some form of a surface scatted electromagnetic wave. It was also found that an Al oxide layer played an important role in forming the nano-patterning on the Al surface.