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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
Analysis on optical pulse propagation in atomic medium for amplification without inversion
Korean Journal of Optics and Photonics, volume 14, issue 5, 2003, Pages 483~490
DOI : 10.3807/KJOP.2003.14.5.483
We have analyzed theoretically optical pulse propagation in a coherent atomic medium for amplification without inversion (AWI), which is achieved by adding incoherent optical pumping to a typical EIT system. In order to explain experimental results [Kim et al., J. Phys. B, 36, 2671(2003)] to control the group velocity of the optical pulse by changing pumping power, we established a 5-level atomic system and applied density matrix equations. This AWI model system is different from previous AWI systems from the viewpoint of using two levels for incoherent optical pumping isolated optically from the EIT (electromagentically induced transparency) system so that more atoms can participate in pulse speed control. We have found that population transfer by collisions between ground states plays a decisive role for efficient AWI, and more atoms are effective for slowing the pulse. Our numerical results are in good agreement qualitatively with experimental results.
A study on JTC optical encryption system using binary CGHs
Korean Journal of Optics and Photonics, volume 14, issue 5, 2003, Pages 491~497
DOI : 10.3807/KJOP.2003.14.5.491
In this paper, an optical encryption system using binary key code based on the joint transform correlator (JTC) is considered. The binary key code is synthesized by using a design technique of the pixel-oriented Computer Generated Holograms (CGHs). The independence and efficiency of the binary encryption key are investigated through computer simulation. To test the efficiency of the encryption system using binary key code, a holographic encryption system is constructed, and the experimental results prove that our holographic encryption system has high ability.
Fundamental condition for the realization of maximal contrast and brightness in liquid crystal display device: II. Polychromatic case
Korean Journal of Optics and Photonics, volume 14, issue 5, 2003, Pages 498~503
DOI : 10.3807/KJOP.2003.14.5.498
We analyze the electro-optic polarization transmission characteristics of liquid crystal cells in the Poincare sphere representation. We determine fundamental conditions on maximizing of brightness and contrast ratio of liquid crystal display devices for polychromatic light by use of retardation films. For optimizing two colors, at least two properly designed retardation films are needed, and for three wavelengths, either it can be approximated to the two-color case or three retardation films are needed.
Point-diffraction interferometer for 3-D profile measurement of light scattering rough surfaces
Korean Journal of Optics and Photonics, volume 14, issue 5, 2003, Pages 504~508
DOI : 10.3807/KJOP.2003.14.5.504
We present a new point-diffraction interferometer, which has been devised for the three-dimensional profile measurement of light scattering rough surfaces. The interferometer system has multiple sources of two-point-diffraction and a CCD camera composed of an array of two-dimensional photodetectors. Each diffraction source is an independent two-point-diffraction interferometer made of a pair of single-mode optical fibers, which are housed in a ceramic ferrule to emit two spherical wave fronts by means of diffraction at their free ends. The two spherical wave fronts then interfere with each other and subsequently generate a unique fringe pattern on the test surface. A He-Ne source provides coherent light to the two fibers through a 2
l optical coupler, and one of the fibers is elongated by use of a piezoelectric tube to produce phase shifting. The xyz coordinates of the target surface are determined by fitting the measured phase data into a global model of multilateration. Measurement has been performed for the warpage inspection of chip scale packages (CSPs) that are tape-mounted on ball grid arrays (BGAs) and backside profile of a silicon wafer in the middle of integrated-circuit fabrication process. When a diagonal profile is measured across the wafer, the maximum discrepancy turns out to be 5.6
with a standard deviation of 1.5
Fabrication and characterization of XPM based wavelength converter module with monolithically integrated SOA's
Korean Journal of Optics and Photonics, volume 14, issue 5, 2003, Pages 509~514
DOI : 10.3807/KJOP.2003.14.5.509
Mach-Zehnder interferometric wavelength converters with monolithically integrated semiconductor optical amplifiers (SOA's) have been fabricated and characteristics of wavelength conversion at 10 Gb/s have been investigated for wavelength span of 40 nm. The devices have been achieved by using a butt-joint combination of buried ridge structure type SOA's and passive waveguides. In the integration, a new method has been applied that removes p+InP cladding layer leading to high propagation loss and forms simultaneously the current blocking and the cladding layer using undoped InP. The module packaging has been achieved by using a titled fiber array for effective coupling into the tilted waveguide in the wavelength converter. Using the module, wavelength conversion with power penalty lower than 1 ㏈ at 10 Gb/s has been demonstrated for wavelength span of 40 nm. In addition, it is show that the module can provide 2R (re-amplification, re-shaping) operation by demonstrating the conversion with the negative penalty.
100 W class flash lamp pumped single stage Nd:YAG Amplifier
Korean Journal of Optics and Photonics, volume 14, issue 5, 2003, Pages 515~520
DOI : 10.3807/KJOP.2003.14.5.515
Characteristics of an amplifier with repetition rate of a few KHz is investigated. The continuous flash lamp pumped Nd:YAG laser head is used as an amplifier. The thermally induced birefringence of the laser medium is compensated and the depolarization is reduced to 5% in a double-pass amplifier. The amplification factor of a four pass amplifier reaches to about 3.2 at the repetition rate 5-10 KHz and the pulse width is lengthened from 40 ns to 48 ns.
Single mode yield analysis of complex-coupled DFB lasers above threshold for various coupling coefficient ratios and facet reflectivity combinations
Korean Journal of Optics and Photonics, volume 14, issue 5, 2003, Pages 521~529
DOI : 10.3807/KJOP.2003.14.5.521
For complex-coupled (CC) DFB lasers, we found that there might be little correlation between the single mode yields at threshold and above threshold. At threshold, the single mode yield considering f number of in-phase (IP) CC DFB lasers is the same as that of anti-phase (AP) CC DFB lasers. However, the single mode yield as a function of injection current above threshold of IP CC DFB lasers is much different from that of AP CC DFB lasers. In the case of IP CC DFB lasers, the single mode yield increases as the coupling coefficient ratio (CR) increases, while, in the case of AP CC DFB lasers, the single mode yield decreases rapidly regardless of CR as the injection current increases. In the case of AR-HR combinations, the effect of AR ref1ectivity on the single mode yield increases as the coupling strength decreases. As the coupling strength decreases, the CR at which the increase rate of the single mode yield starts to decrease, increases, and the maximum single mode yield increases. Single mode yields of AR-HR and AR-AR combinations are larger than those of AR-CL and CL-CL combinations.
A novel 10 Gbit/s all-optical NOR logic gate
Korean Journal of Optics and Photonics, volume 14, issue 5, 2003, Pages 530~534
DOI : 10.3807/KJOP.2003.14.5.530
A novel all-optical NOR gate is proposed and demonstrated for the first time by use of gain saturation in a semiconductor optical amplifier (SOA). It is operated by the nonlinearity of the SOA gain. Hence, to obtain sufficient gain saturation of the SOA, pump signals are amplified by an Er-doped fiber amplifier at the input of the SOA. The operation characteristics of the all-optical NOR gate are successfully measured at 10 Gbit/s.
Sensitivity analysis of 20:1 zoom infrared optical system with zernike polynomial coefficients
Korean Journal of Optics and Photonics, volume 14, issue 5, 2003, Pages 535~544
DOI : 10.3807/KJOP.2003.14.5.535
The sensitivity analysis of a middle wave infrared optical system with 20: 1 zoom ratio is performed to analyze manufacturing and alignment tolerances, and to establish the alignment logic and the focus control strategy. The characteristics of the sensitivities of Zernike coefficients are investigated to all mechanical displacements and several zoom positions using Code-V Macro. From this result, the tolerances of manufacturing and alignment of the optical system are derived and the effective alignment logic is established. Futhermore, an effective focus control strategy is established to make the system simple and compact.
optical modulator capable of complete switching
Korean Journal of Optics and Photonics, volume 14, issue 5, 2003, Pages 545~554
DOI : 10.3807/KJOP.2003.14.5.545
Design of the optical modulator composed of a three-waveguide coupler and CPW traveling-wave electrodes was carried out. Switching phenomena of three-waveguide couplers were analyzed by using the coupled mode theory, and the coupling-lengths of the devices were calculated by means of the FDM. CPW traveling-wave electrodes were analysed by the CMM and SOR simulation technique in order to find the conditions of phase-velocity and impedance matching. Traveling-wave modulators were fabricated on z-cut LiNbO
substrate. Ti was in-diffused in LiNbO
to make waveguides and Au electrodes were built on the waveguides by the electrolyte technique. The fabricated modulator chip was end-polished, pig-tailed and packaged in a brass mount with K-connector. The insertion loss and the switching voltage of the optical modulator were about 4㏈ and 19V, respectively. Network analyzer was used to obtain the S parameter and the corresponding RF response. From the measurement, parameters of the traveling-wave electrodes were extracted to be Z
= 45 Ω, N
=0.055/cm√GHZ. The measured optical response R(
) was compared with the theoretically estimated one, showing both responses agree well. The measurement results revealed that 3㏈ bandwidth turned out to be about 13 GHz.....
Designs of WDM thin film filters for fiber optical communication using an equivalent thin film technique
Korean Journal of Optics and Photonics, volume 14, issue 5, 2003, Pages 555~564
DOI : 10.3807/KJOP.2003.14.5.555
WDM thin film filters for fiber optical communication were designed using Fabry-Prot type multiple cavity filters and an equivalent thin film technique. As the number of cavities in multiple cavity filters increases, it becomes difficult to design the filters due to a great number of variables (the number of cavities, period of reflectors, order of spacers). To solve the problem of design, we treated the fewest variables, regarding symmetrical thin films as equivalent layers, and we applied structural and numerical formulas based on an analysis method of multiple cavity filters. The equivalent thin film technique was able to provide systematic and quantitative design of the WDM thin film filters.
Design of a transflective-type LCD using twisted vertical aligned mode
Korean Journal of Optics and Photonics, volume 14, issue 5, 2003, Pages 565~569
DOI : 10.3807/KJOP.2003.14.5.565
We designed a transflective-type LCD using a twisted VA mode. Generally, a VA mode had a blue shift due to intrinsic properties. We solved this problem using spectroscopic compensation film. We used the front scattering film and negative C-plate to improve characteristics of the viewing angle and contrast ratio. As a result, we found that proposed the transflective-type TVA mode had a contrast ratio of about 80:1, a response time of 22 ms, and a reflectance of 25% in comparison with the standard MgO reflector.