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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 8, Issue 6 - Dec 1997
Volume 8, Issue 5 - Oct 1997
Volume 8, Issue 4 - Aug 1997
Volume 8, Issue 3 - Jun 1997
Volume 8, Issue 2 - Apr 1997
Volume 8, Issue 1 - Feb 1997
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Optical design of flat field anastigmatic three-mirror telescope
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 175~182
To design a high resolution three-mirror telescope for visible spectral region, initial design technique based on the generation of flat field anastigmatic solutions limited by mechanical structure was proposed. An initial design of the three-mirror telescope that features relatively high focal ratio(F/14.5), large aperture diameter(600 mm), and squared field of view(0.27
) was done using an initial design program. Code V was used to optimized the initially designed optical system. As a result, MTF value of the telescope was about 0.5 at Nyquist frequency in each field except for the edge of the CCD.
Design and fabrication of dichroic mirror and broadband H/R mirror for color separation
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 183~188
Cut-off filters would reject all the radiation below and transmit all that above a certain wavelength or vice versa. In this paper, we study design and farbrication of dichroic mirror and broadband high reflective mirror for color separation of white laser beam source to R.G.B color beam source. In laser display system, color separation is very important. We fabricated below specific component for finite color separation of the Kr-Ar laser source. At 45
incidence s-polarized light , it is required that - H/R in blue region R>99%, H/T in green and red region T>90% - H/R in green and red region R>99%, H/T in blue region T>90% - H/R in green region R>99%, H/T in red region T>90% We composed the optical system and realize the full color image.
Stable lateral-shearing interferometer for in-line inspection of aspheric pick-up lenses
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 189~193
Aspheric pick-up lenses are increasingly used in consumer products such as computer and multimedia, as their mass production has become possible owing to the injection molding process. However still much work needs to be done for more effective manufacture of aspheric lenses, one area of which is the in-line inspection of produced lenses. In this paper, we present a lateral-shearing interferometer that has specially been designed to have a high immunity to external vibration and atmospheric disturbance. The interferometer comprises four prisms. They are directly attached to each other using an immersion oil so that relative sliding motions between the prisms are allowed. Their relative displacement can readily generate necessary lateral-shearing and phase-shifting to determine the wavefront of the beam collimated by the lens under inspection. A special phase-measuring algorithm of arbitrary-bucket is adopted to compensate the phase-shifting error caused by the thickness reduction in the immersion oil. Zernike polynomial fitting has done for determinating quantitative aberration of aspheric pick-up lenses. The interferometer built in this work is robust to external mechanical vibration and atmospheric disturbance so that experimental results show that it has a repeatability of less than λ/100.
Spatial realization of a time-varying CGH
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 194~198
We realized CGH display of moving objects with an optical addressed spatial light modulator. CGH was calculated by the horizontal parallex method for saving a calculating time, and calculation speed was improved by making a lookup table of trigonometric function and root calculation. This lookup table was applied to a low resolution SLM, and succeeded in a simultaneous display of the three hologram images by the scanning method.
Profiling of fine displacement of spherical surface using Fourier transform method
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 199~203
Fine displacement of spherical suface was detected and analyzed by Twyman-Green interferometer and the interferogram analysis using Fourier transform method. The surface profile was obtained from single interferogram by introducing the carrier freguency to the interferogram. The interferogram was processed in the spatial frequency domain by fast Fourier transform, and the phase distribution was obtained by inverse Fourier transform. The 3-dimensional distribution for the surface displacement was obtained. It was compared with the calculated surface displacement and the error was less than λ/10.
Instability of the output intensity of Nd:YAG ring laser with the frequency detuning
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 204~208
We analyze the intensity characteristics of the output beams of the ring laser, in which only one mode is generated in each direction, within the neoclassical model by using the Maxwell-Bloch equation. Considering the Nd:YAG crystal as a gain medium, we investigate the stability and the modulation of the output beam intensity as the pumping rate, the relaxation or the decay rate, and the frequency detuning vary, upon taking into account the effect of the beam in one beam in one direction onto the beam in the other direction. In particular, we examine the variation of the output beam intensity and the stability condition through a computer simulation.
Spectral gain variation characteristics of the silica-based erbium doped fiber amplifier in the 1545-1557 nm wavelength region
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 209~212
Spectral gain variation characteristics of the silica-based erbium doped fiber amplifiers is investigated in the 1545-1557 nm wavelength region. For a given length of the erbium doped fiber, the gain(
) with minimum spectral gain variation is uniquely determined. The spectral gain imbalance DG is nearly proportional to the difference between G0 and the operating gain(G) with the proportional constant of 0.1-0.2 dB/dB. For the gain flattened EDFA at the input power of -20 dBm/ch. and the gain of 21 dB, the output power and the optical signal to noise variations after 12 cascaded EDFAs were 5 dB and 3 dB, respectively.
Properties of photoluminescence and time-resolved photoluminescence in doped GaAs
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 213~217
We have measured photoluminescence (PL) and time-resolved PL in doped-GaAs. As increasing doping concentration, the PL spectra of n-type GaAs shift to higher energies while the PL spectra of p-type GaAs shift to lower energies than the bandgap of the undoped GaAs. The contribution of the Burstein-Moss effect overrules the band-gap narrowing in n-type GaAs, contrary to p-type GaAs. The PL rise time and decay time become shorter as increasing doping concentration. The PL rise and decay time in doped-GaAs depend on the type of majority carriers and their concentrations, which imply that the carrier-carrier interaction plays an important role in the energy relaxation processes.
Optical transmission characteristics of a bistable TN LCD
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 218~222
We fabricated a bistable TN LCD with 180
twist angle and confirmed that it has a fast switching response time and a high contrast ratio. We also investigated the effects of the amplitude and width of the reset and selection pulses on a bistable TN LC cell and the conditions of the bistability and the memory time. The range of d/p values showing the bistability is determinded for the pretilt angle according to the rubbing depth.
A study on the polarization transmission characteristics of liquid crystal display devices by means of Berreman's
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 223~229
A source code is developed on the basis of Berreman's 4
4 matrix formalism for the analysis of polarization transmission characteristics of twisted nematic liquid crystal display. By using the program, the polarization transmission characteristics of liquid crystal cells and polarizers are analyzed. For a normally white twisted nematic liquid crystal cell, we obtained a family of iso-contrast contours which helps to understand the viewing angle characteristics of the liquid crystal display device by using the cell. The program also help us to understand the variation of the degree of polarization as well as the deviation of the state of polarization of the light transmitted through the polarizer commonly used in the LCD according to the change in incidence angle. This result suggests the contrast of the images appearing on the LCD can be limited by the characteristics of the polarizer in addition to the liquid crystal cell.
Coupling loss variation as the shape of fiber ends and the fiber arrangement in a fiber Fabry-Perot filter
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 230~235
Coupling loss variation as the shape of fiber ends and the fiber arrangement in a fiber Fabry-Perot cavity, formed with two optical fibers with dielectric mirror coatings on their ends, is analyzed. For the intended features it is assumed that one of two fibers is processed to have a concave mirror whose curvature is the same as that of the wavefront of the Gaussian beam from the first fiber. In this assumption, it was turned out that the coupling loss at the cavity length of 15
is less than 0.5% even with tilt angle of 0.2
, curvature error of 70
, cavity length error of 8
, and lateral alignment error of 0.5
. Thus, low loss and high-finesse fiber Fabry-Perot filters whose cavity length is greater than several
can be obtained easily if the receiving fiber end is properly formed.
Performances of gain-clamped EDFAs with different optical feedback wavelengths for use in WDM networks
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 236~240
We compare feedback wavelength-dependent performances of all-optical gain-clamped 980-nm pumped erbium-doped fiber amplifiers. In a 2.5-Gbps 8-channel WDM system, we have measured and compared gain compressions, signal power variations due to cross-saturation, power penalties caused by relaxation oscillations and noise figures for three different feedback wavelengths - 1532, 1543, and 1565 nm.
Spatially multiplexed volume hologram using an optical fiber
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 241~244
A speckle pattern from an optical fiber is used for a reference beam in writing and reading a volume hologram. The photorefractive volume hologram with this scheme shows good spatial selectivity for spatial(shift) multiplexing because the speckle pattern in writing and reading a hologram looses correlation with a small spatial shift. This scheme has the insensitivity to axial movement. The data storage system with this scheme will have a high storage density and a good stability in operation. We theoretically analyze the diffracted beam from a volume hologram recorded with the speckle pattern from the optical fiber. Experimental results are presented and compared with numerical analysis.
Polymeric digital optical switch with a coupling region modified for optimum mode coupling
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 245~249
An electro-optic polymer digital optical switch with a coupling region modified for optimum coupling is designed and demonstrated. Its branch waveguide is fabricated by reactive ion etching. Then, the modified coupling region is adiabatically introduced along the propagation direction from the branching point of the two waveguides, and it is implemented by photobleaching after the device fabrication. The structure of the modified coupling region and its refractive index profiles are designed to optimize and mode coupling in the Y-branch waveguide. Therefore, the switching performance of the device was shown to be enhanced with a fixed device length. The measured drive voltage is reduced by more than 30 percents, and the crosstalk is also improved by about 4~6 dB.
Minimization of power penalty using chirp parameter for 2.5 Gbps, 8 channel, 400 km optical link system with dispersion and SPM
Korean Journal of Optics and Photonics, volume 8, issue 3, 1997, Pages 250~253
The effect of dispersion in optical transmission system changes according to chirp and SPM. Chirp depends on the modulation condition of an external modulator. SPM is proportional to signal power. In this paper, we analyzed the pulse broadening due to SPM and chirp in the system with dispersion by using Split Step Fourier Method and calculated the optimum chirp parameter for 400 km transmission system. Experimental results are presented also.