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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 8, Issue 4 - Dec 2004
Volume 8, Issue 3 - Sep 2004
Volume 8, Issue 2 - Jun 2004
Volume 8, Issue 1 - Mar 2004
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Optical Power Transfer of Grating - Assisted Directional Coupler with Three - Guiding Channels : TM modes Case
Ho, Kwang-Chun ; Ho, Kwang-Soo ;
Journal of the Optical Society of Korea, volume 8, issue 4, 2004, Pages 149~155
DOI : 10.3807/JOSK.2004.8.4.149
Newly developed modal transmission-line theory(MTLT) is used to analyze rigorously the optical power distribution in grating-assisted directional couplers(GADCs) with three guiding channels. By defining a novel coupling efficiency
amenable to the rigorous analytical solutions of modal transmission-line theory, we explicitly evaluate the power coupling and distribution of TM modes. The results reveal that the incident power is sensitively partitioned through three output channels in terms of such grating parameters as the grating period, the duty cycle, and the operating wavelength.
Spectroscopic Analysis of Gain Bandwidth in Raman Amplifier with Multiwavelength Pumping Scheme Using Actual Band Model
Felinskyi, Georgii ; Han, Young-Geun ; Lee, Sang-Bae ;
Journal of the Optical Society of Korea, volume 8, issue 4, 2004, Pages 156~162
DOI : 10.3807/JOSK.2004.8.4.156
The spectroscopic model is proposed to analyze the gain bandwidth of a fiber Raman amplifier (FRA) with a multiple wavelength pumping scheme based on Raman gain theory. The oscillatory lineshape, which is the analytic function to analyze Raman gain spectra, allows us to estimate the gain bandwidth of the FRA. Based on the proposed theoretical modeling, we design and analyze the characteristics of the FRA using the combined multiwavelength pumping sources. We achieved the extended gain bandwidth of the FRA over 80 nm with the small gain ripple less than 0.5 dB. Threshold pumping power and effective noise figure for the FRA can be also analyzed by using the proposed model, which is also applicable for versatile fibers with other doping materials. The proposed analysis method can be useful for the design of FRA with the multiwavelength pumping scheme.
External Optical Modulator Using a Low - cost Fabry - Perot Laser Diode for Optical Access Networks
Lee, Hyuek-Jae ; Won, Yong-Hyub ;
Journal of the Optical Society of Korea, volume 8, issue 4, 2004, Pages 163~167
DOI : 10.3807/JOSK.2004.8.4.163
We propose and demonstrate an external optical modulation method based on TE/TM-mode absorption nulls in a Multiple Quantum Well(MQW) Fabry-Perot laser diode(FP-LD). The center wavelength of the absorption nulls is rapidly shifted to short-wavelength by the small current change(~1mA) in the FP-LD, which can modulate an optical signal with more than 10 dB of extinction ratio(ER). The shift of the center wavelength comes from the refractive index change due to anomalous dispersion and the plasma effect in MQW FP-LD waveguide. Non-inverting and inverting signals are made by TE- and TM-mode absorption nulls at 155.52 Mbps and BERs for the signals are measured.
Temperature Compensation of a Fiber Optic Strain Sensor Based on Brillouin Scattering
Cho, Seok-Beom ; Lee, Jung-Ju ; Kwon, Il-Bum ;
Journal of the Optical Society of Korea, volume 8, issue 4, 2004, Pages 168~173
DOI : 10.3807/JOSK.2004.8.4.168
Brillouin scattering-based fiber optic sensors are useful to measure strain or temperature in a distributed manner. Since the Brillouin frequency of an optical fiber depends on both the strain and temperature, it is very important to know whether the Brillouin frequency shift is caused by the strain change or temperature change. This article presents a temperature compensation technique of a Brillouin scattering-based fiber optic strain sensor. Both the changes of the Brillouin frequency and the Brillouin gain power is observed for the temperature compensation using a BOTDA sensor system. Experimental results showed that the temperature compensated strain values were highly consistent with actual strain values.
Optical System Design for Thermal Target Recognition by Spiral Scanning [TRSS]
Kim, Jai-Soon ; Yoon, Jin-Kyung ; Lee, Ho-Chan ; Lee, Jai-Hyung ; Kim, Hye-Kyung ; Lee, Seung-Churl ; Ahn, Keun-Ok ;
Journal of the Optical Society of Korea, volume 8, issue 4, 2004, Pages 174~181
DOI : 10.3807/JOSK.2004.8.4.174
Various kinds of systems, that can do target recognition and position detection simultaneously by using infrared sensing detectors, have been developed. In this paper, the detection system TRSS (Thermal target Recognition by Spiral Scanning) adopts linear array shaped uncooled IR detector and uses spiral type fast scanning method for relative position detection of target objects, which radiate an IR region wavelength spectrum. It can detect thermal energy radiating from a 9 m-size target object as far as 200 m distance. And the maximum field of a detector is fully filled with the same size of target object at the minimum approaching distance 50 m. We investigate two types of lens systems. One is a singlet lens and the other is a doublet lens system. Every system includes one aspheric surface and free positioned aperture stop. Many designs of F/1.5 system with
field at the Efl=20, 30 mm conditions for single element and double elements lens system respectively are compared in their resolution performance [MTF] according to the aspheric surface and stop position changing on their optimization process. Optimum design is established including mechanical boundary conditions and manufacturing considerations.
Synthesis and Analysis of Optical Transfer Function of the Modified Triangular Interferometer by Two - pupil Synthesis Method
Kim, Soo-Gil ;
Journal of the Optical Society of Korea, volume 8, issue 4, 2004, Pages 182~187
DOI : 10.3807/JOSK.2004.8.4.182
We synthesized and analyzed the optical transfer function(OTF) of the modified triangular interferometer (MTI) using two-pupil synthesis method. Also, we presented the optimal MTI, which can obtain any bipolar function by combining two wave plates and a linear polarizer. By using the proposed MTI, we can obtain the complex hologram without bias and conjugate image.
Photoacoustic Laser Doppler Velocimetrv Using the Self - mixing Effect of RF - excited CO
Choi, Jong-Woon ; You, Moon-Jong ; Choi, Sung-Woong ; Woo, Sam-Young ;
Journal of the Optical Society of Korea, volume 8, issue 4, 2004, Pages 188~191
DOI : 10.3807/JOSK.2004.8.4.188
A new laser Doppler velocimeter employing a
laser has been developed by using its photoacoustic effect. A change in the pressure of a discharge, induced by mixing of a returned wave with an originally existing wave inside the cavity, is employed to detect the Doppler frequency shift. We found that a Doppler frequency shift as small as 50 kHz was detected, and also a good linear relationship between the velocity and the Doppler frequency shift was obtained.