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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Korean Journal of Optics and Photonics
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Journal DOI :
Optical Society of Korea
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Volume & Issues
Volume 22, Issue 6 - Dec 2011
Volume 22, Issue 5 - Oct 2011
Volume 22, Issue 4 - Aug 2011
Volume 22, Issue 3 - Jun 2011
Volume 22, Issue 2 - Apr 2011
Volume 22, Issue 1 - Feb 2011
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The Study of Thermal Effect Suppression and Wavelength Dependence of Azobenzene-coated FBG for UV Sensing Application
Choi, Dong-Seok ; Kim, Hyun-Kyoung ; Ahn, Tae-Jung ;
Korean Journal of Optics and Photonics, volume 22, issue 2, 2011, Pages 67~71
DOI : 10.3807/KJOP.2011.22.2.067
In the paper, we have demonstrated an azobenzene-coated fiber Bragg grating (FBG) for monitoring ultraviolet light (UV) intensity in remote measurement. The elasticity of the coated azobenzene polymer is changed by the UV light, which induces a center wavelength change corresponding to the change of the FBG's grating period. The wavelength shift resulting from both UV light and other light with the wavelength out of the UV range was about 0.18 nm. In order to improve the accuracy of the measurement, the center wavelength shift caused by radiant heat of the light source was sufficiently removed by using a thermal filter. The amount of the center wavelength shift was consequently reduced to 0.06 nm, compared to the result without the thermal filter. Also, the FBGs coated by using azobenzene polymer were produced by two different methods; thermal casting and UV curing. Considering temperature dependence, UV curing is more suitable than thermal casting in UV sensor application of the azobenzene-coated FBG. In addition, we have confirmed the wavelength dependence of the optical sensor by means of four different band pass filters. Thus, we found out that the center wavelength shift per unit intensity is 0.029 [arb. unit] as a maximum value at 370 nm wavelength region and that the absorption spectrum of the azobenzene polymer was very consistent with the wavelength dependence of the azobenzene-coated FBG.
K-domain Linearization Using Fiber Bragg Grating Array Based on Fourier Domain Optical Coherence Tomography
Lee, Byoung-Chang ; Eom, Tae-Joong ; Jeon, Min-Yong ;
Korean Journal of Optics and Photonics, volume 22, issue 2, 2011, Pages 72~76
DOI : 10.3807/KJOP.2011.22.2.072
We demonstrate a k-domain linearization using a fiber Bragg grating (FBG) array for Fourier domain optical coherence tomography based on a wavelength swept laser. The k-domain linearization is carried out with an interpolation method using a FBG array with five FBGs. The measured signal-to-noise ratio from the point spread function after k-domain linearization is 12 dB improved over that of without k-domain linearization at the 1 mm depth of the sample. Clear OCT imaging of the slide glass with k-domain linearization could be obtained.
Enhancing the Reproducibility of a Photoacoustic Signal Using a Minimum-volume Cell
Kim, Kyong-Seok ; Lee, Kew-Seung ; Ahn, Hong-Gyu ; Lee, Eung-Jang ; Kim, Dae-Kyu ; Park, Seung-Han ;
Korean Journal of Optics and Photonics, volume 22, issue 2, 2011, Pages 77~82
DOI : 10.3807/KJOP.2011.22.2.077
Reproducibility obtained by a minimum-volume cell for photoacoustic (PA) signals is strongly dependent upon the sealing materials and sealing efficiency. Therefore, we have proposed, designed, and constructed an apparatus to enhance the sealing efficiency, and we have examined the reproducibility of amplitude and phase of PA signals with a minimum-volume cell. In particular, we have measured the PA signal as a function of modulation frequency for various rubber O-rings by using our apparatus. The results show that a silicon rubber O-ring can improve the reproducibility of the PA signal and phase by up to 53.4% and 80.4%, respectively, compared to that obtained by using the conventional sealing material, vacuum grease.
Improving the Calculation Speed of Ray-tracing Based Simulator for Analyzing an Integrating Sphere with OpenMP Directive and Guaranteeing the Randomness of Monte Carlo Method
Kim, Seung-Yong ; Kim, Dae-Chan ; O, Beom-Hoan ; Park, Se-Geun ; Lee, El-Hang ; Lee, Seung-Gol ;
Korean Journal of Optics and Photonics, volume 22, issue 2, 2011, Pages 83~89
DOI : 10.3807/KJOP.2011.22.2.083
In order to improve the calculation speed of an integrating-sphere simulator based on a ray-tracing method, parallel processing with OpenMP directive was implemented into the simulator and the randomness of Monte Carlo method was guaranteed by utilizing a parallel random number generator. It was confirmed that simulation results obtained with more than
rays showed good agreement with theoretical results within the error range of 0.5%, and that the calculation speed improved as the number of threads increased. Finally, the spatial response distribution functions of a real integrating sphere were simulated and compared with previous results.
Fabrication of a Liquid Crystal Cell Using ITO-deposited Polarizers as Substrates
Jin, Hye-Jung ; Kim, Ki-Han ; Park, Kyoung-Ho ; Son, Phil-Kook ; Kim, Jae-Chang ; Yoon, Tae-Hoon ;
Korean Journal of Optics and Photonics, volume 22, issue 2, 2011, Pages 90~95
DOI : 10.3807/KJOP.2011.22.2.090
We propose a super-thin and light-weight liquid crystal cell, in which glass substrates are eliminated and polarizers are used as substrates. We fabricate a polarizer substrate by depositing a-SiOX as a buffer layer, indium-tin-oxide as a transparent conducting layer, and a-SiOX as an alignment layer on a polarizer sequentially at a low temperature. We use the ion-beam method to align liquid crystals on polarizer substrates.
Operational and Thermal Characteristics of a Microchip Yb:YAG Laser
Moon, Hee-Jong ; Hong, Sung-Ki ; Lim, Chang-Hwan ;
Korean Journal of Optics and Photonics, volume 22, issue 2, 2011, Pages 96~101
DOI : 10.3807/KJOP.2011.22.2.096
Operational and thermal characteristics of a thin disk Yb:YAG crystal with a thickness of 0.8 mm were studied using as a pumping source a fiber-coupled 930 nm laser diode. The heat generated in the crystal was dissipated by placing both surfaces in contact with copper plates with central hole, and the dependence of the temperature change in the illuminated spot on hole size was investigated by measuring the spectral change of the lasing peaks. The slope efficiency and optical-to-optical efficiency with respect to the LD pump power were as high as 42.2% and 34.8%, respectively. The temperature at the illuminated spot increased with diode current and with increasing hole size of the copper plate. When the hole size considerably exceeded the crystal thickness, the temperature rise deviated from the linear increase at high pump power.
Hybrid-Integrated Tunable Laser Based on Small Double-Ring Resonator with Improved Side Mode Suppression Ratio
Kwon, Oh-Sang ; Chung, Young-Chul ;
Korean Journal of Optics and Photonics, volume 22, issue 2, 2011, Pages 102~107
DOI : 10.3807/KJOP.2011.22.2.102
In this paper, a small double ring resonator reflector was designed and fabricated using a polymer waveguide, and the measurement result was discussed. A widely tunable characteristic of the small double ring resonator caused by the Vernier effect, which results from the difference of the ring radii, was observed. The insertion loss of the double ring reflector was reduced by minimizing the device length to be as short as possible, and thus the output power and the SMSR (side mode suppression ratio) was greatly enhanced. The hybrid integrated laser based on the small double ring resonator reflector lased with the SMSR of 45 dB. In addition, the wide tuning range of 40 nm could be obtained by injecting a current of 30 mA to an electrode on top of the reflector.
Classification of Single-interface Surface Plasmons by Using Complex Differential Diagram
Lee, Dong-Jin ; Lee, Seung-Gol ; O, Beom-Hoan ;
Korean Journal of Optics and Photonics, volume 22, issue 2, 2011, Pages 108~113
DOI : 10.3807/KJOP.2011.22.2.108
In this paper, we propose the complex differential diagram to classify surface plasmon waveguide modes with single interface. To date, surface plasmon waveguide modes are classified using the sign change of the group velocity in the dispersion relation that describes the interrelations between the real wavenumber of the propagation direction and the photon energy. The surface plasmon waveguide modes have the wavenumbers of the direction perpendicular to that in which the wave propagates as well as of the propagation direction, so it is necessary to classify the modes using all of these wavenumbers. The complex differential diagram is a graphical representation with variables of the difference between the real component and the imaginary component of the wavenumber. Using this diagram, the specific mode classification is possible, and it is easy to comprehensively analyze the wavenumber as the function of the photon energy.