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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 14, Issue 6 - Dec 2003
Volume 14, Issue 5 - Oct 2003
Volume 14, Issue 4 - Aug 2003
Volume 14, Issue 3 - Jun 2003
Volume 14, Issue 2 - Apr 2003
Volume 14, Issue 1 - Feb 2003
Selecting the target year
12.5-GHz interleaved bidirectional ultra-dense WDM transmission using the beat-frequency-locking method
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 351~354
DOI : 10.3807/KJOP.2003.14.4.351
We present a 12.5-GHz interleaved bidirectional ultra-dense wavelength-division-multiplexing transmission over a conventional single mode fiber of 80 km achieving spectral efficiency as high as 0.8-bit/s/Hz. The beat-frequency-locking method is used to stabilize the channel frequency within
200 MHz error. To facilitate the identification of multiple beat frequency signals, we use a radio-frequency spectrum analyzer. The bidirectional transmission penalty is about 0.3 dB compared with the unidirectional transmission over the same fiber.
Fiber-to-planar waveguide coupler with a thin metal intermediate layer
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 355~358
DOI : 10.3807/KJOP.2003.14.4.355
We report experimental results on the wavelength and polarization selective coupling properties of fiber-to-planar waveguide coupler having a thin metal intermediate layer. The influence of the metal layer thickness and the refractive index of the superstrate on the device properties has been measured and explained. The proposed device exhibited various application possibilities including polarizers, modulators, and sensors.
A novel vertical directional coupler with polarization independent very short coupling lengths
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 359~364
DOI : 10.3807/KJOP.2003.14.4.359
We propose a novel vertical directional coupler with polarization independent very short coupling lengths using the double-sided deep-ridge waveguide structure which could be implemented using double-sided process to polarization insensitive deep-ridge waveguide structures and investigate the effect of various structure parameters on the coupling length. Variation of coupling length for the variation of the waveguide width is smaller than that for the variation of the core thickness. Coupling length decreases as the inner cladding layer thickness and the core thickness decrease. The waveguide width with the polarization independent coupling length decreases as the inner cladding layer thickness decreases for the same core thickness and the core thickness decreases for the same inner cladding layer thickness.
Mechanically induced Mach-Zehnder interferometers based on long-period fiber grating pair
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 365~368
DOI : 10.3807/KJOP.2003.14.4.365
We have demonstrated mechanically induced Mach-Zehnder interferometers (MZI) based on a long-period fiber grating pair. The transmission spectra, the interference fringes, and the fringe spacing of the long-period fiber grating pairs have also been investigated experimently and analytically. The fringe spacings of the fabricated LPG pairs agree well with the theoretical results.
Analysis of aspheric and diffractive surface effect for long wavelength infrared lens
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 369~376
DOI : 10.3807/KJOP.2003.14.4.369
We analyzed the aspheric and/or diffractive surface effects to the performance in the long wavelength infrared (8-12
m). Also we investigated the dependence of the NA values for the fixed effective focal length 100 mm when the field angle was varied from 5 degrees to 30 degrees stepped by 5 degrees. We chose the merit function as a criteria to compare the performance of the different lenses. Based on the analysis of the aspheric and/or diffractive surface effects, we designed the optical system of F/l.0 for the uncooled thermal imaging system. As for detector the pixel size was 45
m square and the number of pixels were a 320
Digital watermarking using binary phase hologram and optical interferometer
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 377~382
DOI : 10.3807/KJOP.2003.14.4.377
We propose a new optical watermarking method, which can protect the copyright of digital data, using a binary phase hologram and a Mach-Zehnder interferometer. Using a simulated annealing algorithm, the binary phase hologram of the mark image to be hidden is designed. We obtained a watermarked image by linearly superposing the hologram, which is the watermark, in the original image. The extraction processing of the mark image from the watermarked image is achieved by placing the phase-modulated watermarked image on a LCD in one path and the phase-modulated original image on another LCD in the other path in the Mach-Zehnder interferometer. The mark image was obtained by inverse Fourier transforming the phase modulated interference intensity. We confirmed that the proposed method is robust for the cropped images through computer simulation, and we implemented it optically using LCDs which are phase modulation devices.
Optical security system for protection of personal identification information
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 383~391
DOI : 10.3807/KJOP.2003.14.4.383
A new optical security system for the protection of personal identification information is proposed. Personal identification information consisting of a pure face image and an identification number is used for verification and authentication. Image encryption is performed by a fully phase image encryption technique with two random phase masks located in the input and the Fourier plane of 4-f correlator. The personal information, however, can be leaked out in the decryption process. To cope with this possibility, the encrypted image itself is used in the identification process. An encrypted personal identification number is discriminated and recognized by using the proposed MMACE_p (multiplexed MACE_p) filter, and then authenticity of the personal information is verified by correlation of the face image using the optical wavelet matched filter (OWMF). MMACE_p filter is a synthetic filter with four MACE_p (minimum average correlation energy_phase encrypted) filters multiplexed in one filter plane to recognize 10 different encrypted-numbers at a time. OWMF can improve discrimination capability and SNR (signal to noise ratio). Computer simulations confirmed that the proposed security technique can be applied to the protection of personal identification information.
Phase-shifting diffraction grating interferometer for testing concave mirrors
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 392~398
DOI : 10.3807/KJOP.2003.14.4.392
We present a novel concept of a phase-shifting diffraction-grating interferometer, which is intended for the optical testing of concave mirrors with high precision. The interferometer is configured with a single reflective diffraction grating, which performs multiple functions of beam splitting, beam recombination, and phase shifting. The reference and test wave fronts are generated by means of reflective diffraction at the focal plane of a microscope objective with large numerical aperture, which allows testing fast mirrors with low f-numbers. The fiber-optic confocal design is adopted for the microscope objective to focus a converging beam on the diffractive grating, which greatly reduces the alignment error between the focusing optics and the diffraction grating. Translating the grating provides phase shifting, which allows measurement of the figure errors of the test mirror to nanometer accuracy.
Characteristics and analysis of clamp-type optical current transformer using faraday effect
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 399~405
DOI : 10.3807/KJOP.2003.14.4.399
We manufactured a clamp-type optical current transformer (COCT) head using FD10 glass. It was manufactured of two parts of FD10 glass with symmetrical structure and was designed so that light propagates along the critical angle in order to avoid a phase difference with the light within the sensor head at reflection. Also, we measured and analyzed the current of conductor from 0 to 1,000 AT, change of optical power with incidence angle of light, temperature and polarization of light, long-term current measurement using COCT head, and demonstrated the feasibility of manufactured COCT through those experiments.
The radio frequency excited slab waveguide CO
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 406~412
DOI : 10.3807/KJOP.2003.14.4.406
We have developed a radio frequency excited slab waveguide
laser. The dimension of active volume is 2
400 mm. One concave and one convex mirror are used to make the unstable resonator of the positive branch. The radio frequency is 123 MHz and RF input power is varied from 100 to 900 W. The laser gas is set to a pressure of 10∼60 torr and the mixing ratio is
Power extraction efficiency and lasing wavelength distribution of index-coupled DEB lasers above-threshold for various facet reflectivity combinations
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 413~422
DOI : 10.3807/KJOP.2003.14.4.413
We have calculated the power extraction efficiency and the lasing wavelength distribution of index-coupled DFB lasers at threshold for various kL and facet reflectivity combinations, and compared with those above-threshold. The power extraction efficiency increases as the asymmetry of the facet reflectivities increases. The power extraction efficiency above-threshold is slightly larger than that at threshold. Since the relative photon density around the center region increases as kL increases, the power extraction efficiency decreases. The uniformity of the distribution of lasing wavelength over the stop band increases due to the relief of mode degeneracy as the asymmetry of the facet reflectivities increases. In the case of AR-HR combination, the lasing wavelength distributions at threshold are similar to those above-threshold. However, in the case of AR-AR combination, the lasing wavelength at threshold is concentrated on both edges of the stop band, while it is concentrated only on the longer wavelength edge above-threshold. As kL increases, the range of the lasing wavelength distribution increases due to the increase of the stop band. The effect of AR reflectivity on the power extraction and the lasing wavelength distribution is very weak.
The structural dependence of current blocking layers on the static and dynamic performances in a direct modulated semiconductor laser
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 423~428
DOI : 10.3807/KJOP.2003.14.4.423
In a direct modulated semiconductor laser diode. the structural dependence of current blocking layers was studied in view of the leakage current reduction and the bandwidth expansion. To analyze the leakage current and the parasitic effects, the current-voltage derivation characteristics and the subtraction method were used, respectively. It was shown that the‘inin’type current blocking structure might be the best choice for the purpose of the static and dynamic characteristics.
Theoretical analysis of the lightwave localization phenomenon on the random transmission line (part 1) : localization characteristics of the solution of propagation equation
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 429~433
DOI : 10.3807/KJOP.2003.14.4.429
We try to analyse the localization phenomenon of a lightwave in random media by means of considering the solution of the propagation equation on a transmission line in which the propagation constants are randomly distributed. Lightwave localization is generated at the turning point where the solution is changed suddenly from an increase to a decrease. First, in order to investigate the changing process of the solution, we have derived the approximated one-dimensional Schrodinger equation from the two-dimensional wave equation by using the Brags condition. Considering the many types of solutions of the wave equation, we have investigated the conditions that allow the solutions to exist. Also, we have investigated the relationships between the localization of the solution and the variation of the propagation constant. In case of the exponential solution, we know that the permittivity
Theoretical analysis of the lightwave localization phenomenon on the random transmission line (part 2) : simulation
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 434~442
DOI : 10.3807/KJOP.2003.14.4.434
Taking advantage of the probability function, we have analyzed the localization phenomenon of the solution of a propagating function under the condition that the propagation constants are randomly distributed. For example, we have investigated the localization phenomenon of the voltage wave for a transmission line in which the characteristic impedance is randomly distributed. We have confirmed that the localized solution is in existence on the random lossless transmission line. Even in the case that the voltage wave is impulsively excited by the current source, the voltage wave is localized. Because the light wave is seriously affected at the localized position in the lossy transmission line, we have determined that the light wave localization phenomena are generated by multi-reflection.
A study on optimum design of a lightweight mirror
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 443~448
DOI : 10.3807/KJOP.2003.14.4.443
A study on optimum design of the lightweight mirror of a satellite camera is presented. An optical surface deformation of the lightweight mirror, which is a principal component of the camera system, is an important factor affecting the optical performance of the whole camera system. In this study, optimum design of the lightweight mirror is presented. Total weight of the mirror to reduce the optical surface deformation and the launching cost is used as an objective function. Peak-to-valley value and natural frequency of the mirror are given as constraints to the optimization problem. The sensitivities of the objective function and constraint are calculated by a finite difference method. The optimization procedure is carried out by the commercial optimizer, DOT. As a verification of the optimum design of the mirror, two design examples are treated. In the real application example, the lightweight mirror with 600mm effective diameter is treated. The optimized results with various design variables, which are obtained by considering thickness limitations, are analyzed.
Suppression of polarization effects in Er-doped fiber source for gyroscope by polarization scrambling
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 449~453
DOI : 10.3807/KJOP.2003.14.4.449
In a broadband erbium-doped fiber source for fiber optic gyroscope, a pump-polarization scrambling scheme is used to suppress the polarization dependence of the source mean wavelength. The degree of polarization of the pump is reduced to 1.4% by applying proper modulation depth to the polarization modulator where 10 m-long single-mode fiber is wound on a cylindrical PZT. In the case of using the pump-polarization scrambler as well as the output depolarizer, the mean-wavelength variations due to the random change of polarization are measured to be less than our measurement limit of 5 ppm.
All-optical mach-zehnder interferometric wavelength converter monolithically integrated with loss-coupled DFB probe source
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 454~459
DOI : 10.3807/KJOP.2003.14.4.454
We report the first demonstration of 10 Gb/s wavelength conversion in a Mach-Zehnder interferometric wavelength converter monolithically integrated with a loss-coupled DFB probe source. The integrated device is fabricated using a BRS (buried ridge stripe) structure with an undoped InP clad layer on the top of a passive waveguide to reduce high propagation loss. The device exhibited a static extinction ratio of 11 dB. Good performance at 10 Gb/s is obtained with an extinction ratio of 7 dB and a power penalty of 2.8 dB at a 10
bit error rate.
Characteristics of erbium-doped fiber sources with double-pass forward configuration for gyroscope application
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 460~465
DOI : 10.3807/KJOP.2003.14.4.460
Characteristics of 0.98
m-pumped erbium-doped fiber (EDF) sources with double-pass forward (DPF) configuration are analyzed by numerical calculation. Various source characteristics such as output power, spectral width and mean-wavelength stability are investigated with the variation of EDF length, pump power and pump wavelength. Some of the numerical results are compared with experimental ones for verification. The results show that the characteristics of sources with DPF configuration can change considerably with the EDF length. It is also found that an optimum design can exist for stable mean-wavelength against fluctuations of pump power and pump wavelength.
An optical true time delay for 10 GHz linear phased array antennas composed of optical 2×2 MEMS switches and fiber delay lines
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 466~472
DOI : 10.3807/KJOP.2003.14.4.466
In this paper, we proposed an optical true time-delay (TTD) feeder system for phased array antennas (PAAs). The system possesses high-speed beam scan capability since, in this scheme, different lengths of fiber delay-lines are selected by optical 2
2 MEMS switches at high speed. An optical TTD capable of beam scanning in one of eight different directions has been built for 10 GHz linear PAA systems. Experimental results on time delay measurements show that the maximum time delay error is less than 0.2 ps corresponding to a scan angle error of less than 0.84o. We have also designed a 10 GHz linear PAA composed of eight micro-strip patch antenna elements driven by the proposed TTD, and the radiation patterns of this PAA have been analyzed by simulation.
A study on the color management between scanner and monitor using multiple regression method
Korean Journal of Optics and Photonics, volume 14, issue 4, 2003, Pages 473~479
DOI : 10.3807/KJOP.2003.14.4.473
The purpose of this study is to recover the CIE XYZ tristimulus values of original colors from scanner output signals, and to reproduce true colors on the monitor. The process of this study is composed of three steps; scanner characterization, chromatic adaptation transformation, and color space transformation between and sRGB. Especially, in the process of recovery, scanner stimuli were obtained accurately by dividing the non-linear photometric response curve into two parts. As the result of test to EPSON Expression 1680 scanner, the average color difference between true and recovered XYZ for 228 target colors, 22 test neutrals, and 36 test colors were 1.49, 0.97, and 1.42
*, respectively. With the transformation from illuminant D50 to illuminant D65, the input signals to sRGB monitor were predicted. Finally, it could be found that displayed colors with predicted input signals were very consistent with true colors. with true colors.