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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 15, Issue 6 - Dec 2004
Volume 15, Issue 5 - Oct 2004
Volume 15, Issue 4 - Aug 2004
Volume 15, Issue 3 - Jun 2004
Volume 15, Issue 2 - Apr 2004
Volume 15, Issue 1 - Feb 2004
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Purely Phase-Sampled Fiber Bragg Gratings with uniform bandwidth for Broadband Dispersion and Dispersion Slope Compensation
Lee Hojoon ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 485~489
DOI : 10.3807/KJOP.2004.15.6.485
We demonstrated numerically that both the chromatic dispersion and the dispersion slope could be compensated by using purely phase-sampled superstructure fiber Bragg gratings provided with chirp of coupling coefficient along the wavelength axis. Also, we propose a purely phase-sampled Bragg grating for dispersion and dispersion slope compensation by introducing a chirp in coupling coefficient and sampling function. The bandwidth of all reflected channels can be equalized.
Fabrication of gratings in Planar Lightwave Circuits for External Cavity Laser
Lim, Jong-Hoon ; Lim, Gun ; Lee, Kyung-Shik ; Song, Jeong-Hwan ; Cho, Jae-Geol ; Jung, Sun-Tae ; Oh, Yun-Kyung ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 490~494
DOI : 10.3807/KJOP.2004.15.6.490
Bragg gratings were fabricated in Ge-doped silica planar lightwave circuits (PLC) for different writing conditions to study the growth characteristics. The refractive index modulation of the gratings grew in the PLC with total fluence F according to the power law
Analysis of the Plane-Concave Fabry-Perot cavity for a tunable filter
Yeh YunHae ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 495~502
DOI : 10.3807/KJOP.2004.15.6.495
We proposed an analysis model for a Fabry-Perot cavity constructed with a plane-mirrored optical fiber and a concave-mirrored one. We presented the analysis results calculated by inserting practical values into the equations derived. The coupling loss of the cavity and the mirror loss are the most important parameters in reducing the insertion loss of the filter. In order to build a filter of finesse 600, FSR 57 nm, and insertion loss < 3 dB, the plane-concave cavity using mirrors of loss < 0.09% should be aligned for the coupling loss to be less than 0.1 %.
A Very Short Vertical Directional Coupler Switch with Polarization Independent Very High Extinction Ratios
Jung Byung-Min ; Kim Boo-Gyoun ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 503~510
DOI : 10.3807/KJOP.2004.15.6.503
We propose a novel vertical directional coupler switch using a vertical directional coupler with polarization independent coupling lengths employing the doublesided deep-ridge waveguide structure. This switch is composed of a switching operation induced section with symmetric structures and an extinction ratio enhanced section with asymmetric structures. We present design methods and examples for this switch with very short lengths and very high extinction ratios larger than 30 dB for both TE and TM modes in cases of both cross and bar states.
Performance evaluation by simulation for the angular luminous intensity distributions of marine lanterns using a tilting aspherical Fresnel lens and a C-8 type light bulb
Cho Hyun Seok ; Jo Jae Heung ; Park Seungl Nam ; Park Chul Woung ; Kim Yong Wan ; Kim Jong Tae ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 511~518
DOI : 10.3807/KJOP.2004.15.6.511
Providing marine signal lanterns with advantages of little weight as well as large aperture, a Fresnel lens has been adopted to transfer the beam from the lanterns up to 10 nautical miles (18.53 km). A Fresnel lens with the diameter of 250 mm and 300 mm was designed by a lens design program and optimized by adjusting the groove parameters of the lens. The angular luminous intensity distribution (ALID) of this lens was calculated by using an illumination analysis program considering the ALID of a light bulb. At the best alignment of the bulb, the maximum luminous intensities (MLI) of the lantern were 1000 cd (in the case of 250 mm diameter) and 1300 cd (in the case of 300 mm diameter). These are more than the critical value of 720 cd that is the Korean Standard of MLI for the marine lantern. The ALID was investigated as a function of misalignment from the lens focus to determine the tolerance of the alignment ranges.
Optimum Lens Organization and System Set-up for 2-Dimensional Imaging of Biophoton
Yi Seung-Ho ; Shim Seong-Bo ; Kim Jai-Soon ; Yang Joon-Mo ; Lee Changhoon ; Soh Kwang-Sup ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 519~526
DOI : 10.3807/KJOP.2004.15.6.519
We developed a 2-D imaging system to detect ultra weak biophoton by using a high sensitive fast CCD camera. We installed an illumination apparatus to generate delayed luminescence from plant leaves. Shutters at the illumination system and detector were synchronized to each other. The lens system of the CCD camera was newly designed to accommodate the specific requirements to enhance the collection efficiency for biophoton. Based on the lens simulation, commercial lenses were chose for the lens system. All the equipment was installed in a multi-purpose dark box and the delayed luminescence of Euonymus japonica was successfully acquired.
Technique of measuring optic axis off-alignment error for LCD polarizing and compensating plates by using a polarimetry
An Sung Hyuck ; Kim Sang Jun ; Kim Sang Youl ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 527~530
DOI : 10.3807/KJOP.2004.15.6.527
Using a polarimetry based on the rotating analyzer ellipsometer, a technique of measuring off-alignment angle between the slow-axis of the LCD (Liquid Crystal Display) polarizing plate and the transmission axis of the compensating plate attached to the polarizing plate is proposed. It is anticipated that this technique will reduce the optic axis off-alignment error coming from the process of attaching the compensating plate to the LCD polarizing plate markedly, and therefore will help maintain the quality of LCD display image uniformly.
Precise Adsorption Measurement Technique by a Phase Modulated Ellipsometry
Choi, B.I. ; Nham, H.S. ; Park, N.S. ; Youn, H.S. ; Lim, Tong-Kun ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 531~538
DOI : 10.3807/KJOP.2004.15.6.531
Studies of adsorption isotherms with sharp step-wise layer condensation help us to better understanding of two dimensional layers. For this, an adsorption isotherm apparatus, using a phase modulated ellipsometric technique, has been constructed and an adsorption experiment has been performed. With subatomic scale resolution(∼0.3
), the adsorption processes could be observed by ellipsometric signals. On measurement of multilayer adsorption of argon on highly oriented pyrolytic graphite(HOPG), thousands of adsorbed layers were observed at 34.04 K, which suggests that the adsorption is completely wet. On the contrary nine sharp layers of steps for adsorptions and desorptions were observed at 67.05 K. These isotherms obtained can provide a lot of information about thermodynamic states, bonding energies between adsobate and substrate, and structure transitions in the adsorbed film.
Low Coherence Interferometer for Measurement of Path Length Errors in Arrayed-Waveguide Grating
Song, Young-Ki ; Heo, Nam-Chun ; Chung, Young-Chul ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 539~546
DOI : 10.3807/KJOP.2004.15.6.539
An improved low coherence interferometer system and a new analysis method for the accurate measurement of the optical path difference error of an AWG (Arrayed-Waveguide Grating) are described. The use of software simplifies the experimental setup by eliminating the hardware (clock generator). In addition, the actual distances between the peak positions of the adjacent interference signals are calculated using interpolation methods. The wavelength transmission characteristics of the AWG are calculated assuming the measured phase errors. The calculated AWG characteristic is quite similar to the actual measurement result, confirming accuracy of the proposed measurement setup.
A Study on Fabrication and Performance Evaluation of Ti:LiNbO
Polarization Mode Controllers
Moon, Je-Young ; Jung, Hong-Sik ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 547~554
DOI : 10.3807/KJOP.2004.15.6.547
We investigated a LiNbO
based integrated-optic polarization controller with the Ti-indiffused waveguide along the z-axis utilizing the electro-optic effect. The device consists of a first quarter-wave (λ / 4) followed by a half-wave (λ / 2) and a second quarter-wave (λ / 4) wave-plate. We analyzed the amount of phase change and the transformation of the polarized mode as a function of the combination of wave-plates and of their applied voltages. The operation has been systematically measured utilizing a polarimeter and Poincare sphere. We confirmed that the fabricated device controls the transformations from any arbitrary input state of polarization (SOP) into any general output SOP.
Improvement of 3-Dimensional Finite-Difference Beam Propagation Method by Combining the Implicit and the Explicit methods
Kim, Hyun-Jun ; O, Beom-Hoan ; Park, Se-Geun ; Lee, El-Hang ; Lee, Seung-Gol ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 555~562
DOI : 10.3807/KJOP.2004.15.6.555
We propose a hybrid method combining the implicit with the explicit methods in order to reduce the calculation time and improve the convergence problem of the 3-dimensional finite-difference beam propagation method. The numerical simulation of a directional coupler is carried out by the proposed method. It is found from the simulation results that the calculation speed of our method is 10 times faster than that of direct solving techniques.
Characterization of refractive index profile in LiNbO
waveguides fabricated by high temperature proton exchange method
Shin, Myung-Jin ; Cho, Hyun-Ju ; Lee, Jae-Cheul ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 563~568
DOI : 10.3807/KJOP.2004.15.6.563
The high temperature proton exchange (HTPE) method was used to fabricate optical waveguides based on LiNbO
, which gives rise to low propagation loss and high polarization extinction ratio. To characterize the refractive index distribution of the fabricated waveguides, the guided modes of each waveguide were observed using the prism coupling method and then the refractive index profile was calculated by the inverse WKB method with the least square fitting. Finally, we showed how the HTPE parameters such as the temperature of PE, the concentration of lithium additive, and the time of PE effect the refractive index profile.
Frequency and power stabilization of radio frequency excited CO
laser using photoacoustic effect
Choi, Jong-Woon ; Yu, Moon-Jong ; Woo, Sam-Yong ; Suh, Ho-Suhng ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 569~574
DOI : 10.3807/KJOP.2004.15.6.569
We stabilized the frequency and power of a CW radio-frequency-excited
laser on the peak of the Doppler broadened gain curve using the photoacoustic effect generated from the laser itself. The condenser microphone is installed in the radio frequency discharge chamber to detect a photoacoustic signal. The photoacoustic signal is fed to a lock-in stabilizer as a reference signal for stabilization. The frequency stability is estimated to be better then 5.4
at the P(20) line. The stabilized output variation was reduced 9.3%, compared to 100% for a free running laser.
Numerical analysis of resonator stability and beam quality in a thermal-birefringence compensated symmetric resonator consisting of two laser rods with rod-end curvatures
Kim, Hyun-Su ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 575~582
DOI : 10.3807/KJOP.2004.15.6.575
We analyse the beam characteristics of the thermal-birefringence compensated symmetric resonator which consists of two laser rods with rod-end curvatures. The numerical results show that the stability and the beam quality can be improved in high power operation region when the rod-ends are made in the form of a negative lens. The thermal birefringence of the symmetric two-rods resonator is shown to be well compensated when the two rods closely contact each other.
Autofocus of Infinity-Corrected Optical Microscopes by Confocal Principle and Fiber Source Modulation Technique
Park, Jung-Jae ; Kim, Seung-Woo ; Lee, Ho-Jae ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 583~590
DOI : 10.3807/KJOP.2004.15.6.583
The autofocus is one of the important processes in the automated vision inspection or measurements using optical microscopes, because it influences the measuring accuracy. In this paper, we used the confocal microscope configuration based on not a pinhole but a single-mode optical fiber. A single mode fiber has the functions of source and detector by applying the reciprocal scheme. As a result, we acquired a simple system configuration and easy alignment of the optical axis. Also, we embodied a fast autofocus system by acquiring the focus error signal through a source modulation technique. The source modulation technique can effectively reduce physical disturbances compared with objective lens modulation, and it is easily applicable to general optical microscopes. The focus error signal was measured with respect to the modulation amplitude, reflectance of the specimen and inclination angle of the measuring surface. The performance of the proposed autofocus system was verified through autofocusing flat mirror surface. In addition, we confirmed that source modulation rarely degrades the depth resolution by the comparison between the FWHMs of axial response curves.
Continuous Photonic RF True-time Delay Using a Side-polished Fiber Bragg Grating with Heating Electrode
Chae, Ho-Dong ; Kim, Do-Hwan ; Kim, Hyoung-Jun ; Lee, Sang-Shin ; Kim, Hyo-Kyeom ; Lee, Kyu-Hyo ; Kim, Kwang-Taek ;
Korean Journal of Optics and Photonics, volume 15, issue 6, 2004, Pages 591~596
DOI : 10.3807/KJOP.2004.15.6.591
In this paper, a photonic RF true-time delay based on a partially side-polished fiber Bragg grating with heating electrode has been proposed and fabricated. It features continuous voltage-controlled operation, requiring no mechanical perturbation and no moving parts. For an RF signal carried over an optical signal, the time delay has been obtained by controlling the voltage applied to the electrode and thus adjusting its reflection positions from the fiber grating via the thermooptic effect. The achieved time delay is about 100 ps with the electrical power consumption of 280 mW.