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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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Impmvement of Inverse Fitting Algorinlm of Visible Reflectance Spectrum to Extract Skin Parameters
Choi, Seung-Ho ; Im, Chang-Hwan ; Jung, Byung-Jo ;
Korean Journal of Optics and Photonics, volume 18, issue 3, 2007, Pages 179~184
DOI : 10.3807/HKH.2007.18.3.179
In order to extract more accurate skin parameters, this study was focused on the improvement of the efficiency of a previous inverse fitting algorithm based on genetic algorithms. The algorithm provides the best fitting result of the diffusion approximation model to a VRS (visual reflectance spectroscopy) curve of skin. Simplex and wavelength selection methods were applied to the previous algorithm. Nine skin parameters were inversely extracted from the modeling studies. The revised inverse fitting algorithm was determined to produce an 83% reduction of computation time and a 0.64% reduction of sum of square error, compared to the previous algorithm. In conclusion, we confirmed that the new algorithm provides faster and more accurate solutions for the diffusion approximation model.
Performance of CWDM Fabricated by the PLC-AWG Technology
Moon, H.M. ; Kwak, S.C. ; Hong, J.Y. ; Lee, K.H. ; Kim, D.H. ; Kim, J.J. ; Choi, S.Y. ; Lee, J.G. ; Lee, J.H. ; Lim, K.G. ; Kim, J.B. ;
Korean Journal of Optics and Photonics, volume 18, issue 3, 2007, Pages 185~189
DOI : 10.3807/HKH.2007.18.3.185
A novel technology for CWDM (Coarse Wavelength Division Multiplexer) utilizing a PLC (Planar Lightwave Circuit)-AWG (Arrayed Waveguide Grating) fabrication process is proposed. BPM (Beam Propagation Method) Simulation results on the employed parabolic-horn-type input slab waveguide of AWG and the performance of the 20 nm-channel spacing CWDM with flattened passband are presented. Waveguides of
have been used in this experiment and the insertion loss at the peak wavelength is 3.5 dB for a Gaussian spectrum and is 4.8 dB for a flat-top spectrum. The bandwidth at 3 dB is better than 10 nm and 13 nm for Gaussian and flat-top spectra, respectively.
Novel Optical Coupling Filters using Leaky Characteristics of Metal-Strip Gratings
Ho, Kwang-Chun ;
Korean Journal of Optics and Photonics, volume 18, issue 3, 2007, Pages 190~195
DOI : 10.3807/HKH.2007.18.3.190
A novel optical coupling filter with finite-thickness metal-strip gratings printed on optical planar dielectric slabs is proposed, and Bragg conditions of the device are rigorously evaluated by using Modal Transmission-Line Theory (MTLT). The numerical results reveal that the guiding structures have filtering properties due to a leaky-wave stop-band while conventional DFB guiding structures consisted of dielectric gratings depend on a feedback-wave stop-band. Consequently, it shows that the optical coupling titter dependent on the leaky-wave filtering characteristics can be compounded of such optical devices as LD and optical fiber.
Theoretical Study of Brillouin OTDA using Two Pulse Insets
Hong, Yong-Hyun ; Lee, Ho-Joon ;
Korean Journal of Optics and Photonics, volume 18, issue 3, 2007, Pages 196~201
DOI : 10.3807/HKH.2007.18.3.196
A theoretical study of Brillouin optical time domain analysis (BOTDA) using two pulse lasers is performed. Even though a point detection is made for a pump pulse period, the dynamic range of BOTDA using two pulse lasers is approximately 5 dB more than that of a pulse and a CW laser when the fiber length is 140 km and the Stokes power is 1 mW.
Optical Visual Cryptography using the Characteristics of Spatial Light Modulation
Yi, Sang-Yi ; Wi, Sung-Min ; Lee, Seung-Hyun ; Yoo, Ji-Sang ; Kim, Dong-Wook ;
Korean Journal of Optics and Photonics, volume 18, issue 3, 2007, Pages 202~207
DOI : 10.3807/HKH.2007.18.3.202
Optical visual cryptography (OVC) based on binary computer generated holograms (BCGH) is proposed. OVC used optics instead of human eyesight for decryption of visual cryptography (VC). As a result, it was possible to adapt cryptography to an optical system. However, it also had some difficulties because it did not overcome the existing problems of VC completely. This paper suggests a method of optical cryptography implementation based on the phase modulation characteristics of a liquid crystal display (LCD). The problems are evaluated by simulation. This system shows that the noise is reduced and resolution is improved compared with the conventional OVC.
Thermal Lens Compensation in a Fiber-Coupled Laser-Diode Pumped Ceramic Nd:YAG Laser
Kim, Duck-Lae ; Kim, Yeong-Sik ; Kim, Byung-Tai ;
Korean Journal of Optics and Photonics, volume 18, issue 3, 2007, Pages 208~215
DOI : 10.3807/HKH.2007.18.3.208
A fiber-coupled laser-diode pumped ceramic Nd:YAG laser for compensating the thermal tensing effect was developed. The thermal tensing effect was compensated using a convex lens, which was 25 mm away from the laser rod, with a focal length of 30 mm and an effective clear aperture of 22 mm. Without a compensator, the laser output power decreased suddenly above a pump power of 6 W. Using a compensator, the laser output power increased linearly according to the pump power. The beam propagation factor
was 2.4 under a pump power of 12 W.
Widely Tunable Double-Ring-Resonator Add/Drop Filter
Lee, Dong-Hyun ; Lee, Tae-Hyung ; Park, Joon-Oh ; Kim, Su-Hyun ; Chung, Young-Chul ;
Korean Journal of Optics and Photonics, volume 18, issue 3, 2007, Pages 216~220
DOI : 10.3807/HKH.2007.18.3.216
A widely tunable add/drop filter composed of double ring resonators is implemented with high-index-contrast polymer waveguide. To enhance the productivity, directional couplers are designed to have good fabrication tolerance. The refractive indices of the core and cladding in the 1550 nm wavelength are 1.51 and 1.378, respectively. Drop response in comparison with neighborhood peak gets enhanced by more than 2.9 dB at the wavelength where both rings resonate. This filter can be used to build widely tunable laser diode through hybrid-integration with reflective SOA.
Opticsal Characteristics of Bismuth-doped Aluminosilicate Glass Codoped with Li and Ge
Seo, Young-Seok ;
Korean Journal of Optics and Photonics, volume 18, issue 3, 2007, Pages 221~225
DOI : 10.3807/HKH.2007.18.3.221
The possibility of improving amplification characteristics and lowering the melting point of bismuth-doped aluminosilicate glass as a new amplification material, which has broadband near-infrared emission at 1300 nm regions, was investigated. Spectroscopic analysis of bismuth-doped aluminosilicate glass shows that the addition of an alkali metal oxide,
increases FWHM of fluorescence spectrum but decreases fluorescence intensity, while
composition increases both FWHM of fluorescence spectrum and fluorescence intensity. Also, excellent optical amplification gain characteristics in a
-added sample were observed.
A Study on the Propagation Characteristics in Double Metal Strip Waveguides
Lee, Sang-Jun ; Kim, Sang-In ; Song, Seok-Ho ;
Korean Journal of Optics and Photonics, volume 18, issue 3, 2007, Pages 226~231
DOI : 10.3807/HKH.2007.18.3.226
In this paper, we analyze the characteristics of various curved waveguides composed of double metal strips using finite difference method (FDM). Our investigation reveals that the bending loss of the double metal strip waveguide can be improved with less degradation of the straight waveguide's propagation loss compared to the single metal strip structure. Optimization of the double metal strip waveguide structure has been conducted considering bending and propagation losses.