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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 11, Issue 6 - Dec 2000
Volume 11, Issue 5 - Oct 2000
Volume 11, Issue 4 - Aug 2000
Volume 11, Issue 3 - Jun 2000
Volume 11, Issue 2 - Apr 2000
Volume 11, Issue 1 - Feb 2000
Selecting the target year
Laser cooling and temperature measurement of cesium atoms
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 379~384
We cooled cesium atoms below the Doppler cooling limit by laser cooling. For this deep cooling of atoms, the laser frequency was shifted by using the Zeeman shift of an absorption line of cesium. The stabilization of the laser frequency was maintained while the laser frequency was shifted by 40 MHz within 2 ms. The lowest temperature of the laser-cooled cesium atoms was
in this experiment. We measured the temperature of the laser-cooled cesium atoms as a function of the frequency detuuing and the intensity of the cooling laser. The results agreed well with the ones calculated by two-photon laser cooling theory.theory.
Quantitative analysis of increase in depth of focus using Wigner distribution function
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 385~389
A phase-retardation function which was derived from Wigner distribution function (WDF) is used to increase a focal depth of a radially symmetric optical system. The WDF for one-dimensional signal is represented as a two-dimensional function of phasespace (
), and a normalized irradiance is described as a form of the Strehl ratio (SR). The increase in the focal depth is accomplished by delivering a shearing tilt a that represents a characteristic of free space propagation with simple manipulation in the WDF space. In this paper we propose a method for evaluating the focal depth quantitatively by representing the phaseretardation function in terms of the focal depth term. In order to verify the validity of the proposed method, we compared the numerically analyzed result with that of J. Sochki's study. study.
Optical system design for recognition of human iris
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 390~394
An optical system for iris pattern recognition of the human eye is designed. The lens system is triplet type, and characterized to minimize longitudinal chromatic aberration and Petzval sum. The distance from object to image is 200 mm-300 mm and the effective focal length is 50 mm. Performance of the imaging system is assessed by calculating the ray-fan and spot diagram for Fraunhofer C, d and F line for object height 0 mm, 4 mm and 6 mm. Furthermore, MTFs are calculated. All of the spot sizes are less than 0.05 mm in diameter. The MTF values are higher than 0.5 in the spatial frequency range up to 20 lines/mm for all of the object heights. ights.
A comparative study on peak finding algorithms in white light interferometry
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 395~399
In white light interferometry, fast and accurate localization of the fringe visibility is the most essential part in application of the principle. So much attention has been concentrated on speeding up the process, we in this study decided to investigate the results of the various peak-finding algorithms. Of the many approaches, two most simplistic algorithms were selected for their straightforwardness and robustness. Both were equally accurate in measuring the step height of a sample, but the method based on the weighted average technique proved to be truer to the surface topography. A model explaining the shortcomings of the correlation technique is presented. ented.
All optical clock recovery from 10 Gb/s RZ signal using an actively mode-locked figure eight laser incorporating a SLALOM
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 400~404
All-optical clock recovery from a 10 Gb/s RZ signal has been demonstrated using an actively mode-locked figure-eight laser incorporating a semiconductor optical amplifier in the loop-mirror scheme. Optical pulses with 10 ps pulse width were modulated by a LiNb03 external modulator at
PRES and injected into the clock recovery circuit to extract optical pulses with 12 ps width. Regeneration of the original bit pattern has been accomplished by modulating the recovered clock with the same modulator, and no power penalty was observed at
Improved design of a directional coupler by a novel concept
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 405~410
We propose a novel design concept to improve extinction ratio by minimizing
. Improvements of loss and fabrication error limit are also obtained by this hybrid design of the lateral shift and curved waveguide to control transfer coefficients,
. The concept of lateral shift merges two transfer coefficients, and additional curved waveguide controls mode profile asymmetrically to help this minimizing effect of
with no serious decrease in transfer efficiency. For a given InP based waveguide structure, the mode propagation analysis with an effective index approximation provided a calculational improvement of extinction ratio to -39 dB and fabrication error limit to
, with a structure design of
waveguide curvature and
lateral shift. shift.
Spot-size converter design of an
SSC-FP-LD for optical subscriber network
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 411~417
The waveguide structure effects of a spot-size converter (SSe) of a
FP(Fabry-Perot)-LD(Laser Diode) were investigated. Its coupling efficiency and alignment tolerance with a single-mode fiber (SMF) were carefully examined by using a 3dimensional BPM (Beam Propagation Method). It was shown that the fOlmation of enough length of straightened waveguide around the end of the sse region can substantially improve the optical coupling efficiency for a vertically tapered sse. In contrast, a down-taper structure for a laterally tapered sse has superior characteristics to an up-tapered one. We suggested good sse structures which can provide a high coupling efficiency as well as a large alignment tolerance with an .SMF. .SMF.
Fabrication of multi-mode interference
optical power splitter using glass integrated optics
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 418~422
In this paper, we have modeled and fabricated a mutimode interference (MMI)
optical power splitter using finite-difference beam propagation method and
ion-exchanged method in BK7 glass. The power splitting ratio of the fabricated MMI
optical power splitter shows 0.46 dB..46 dB.
A study of the sidelobe supprion in an acousto-optic wavelength tunable filter utilizing a SAW-guide directional coupler
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 423~428
We have demonstrated a -8 dB additional reduction in the intensity sidelobe of an apodized-interaction-strength guide-wave acousto-optic filter with a center passband of 1551.6 nm. Acoustic-intensity weighting was achieved by launching a surface acoustic wave (SAW) beam in a straight acoustic waveguide, and gradually transferring this SAW intensity to the active device, and back out, by evanescent-wave coupling across a 50 !lm barrier over a 19 rom interaction length. The intensity sidelobe was -4.27 dB for an unapodized filter with abmpt onset and cutoff of the interaction, but sidelobes were reduced to at most -12.68 dB for a SAW intensity with raised-cosine weighting. The RF driving power was 17.78 mW. A linear tuning rate of 8.86 nmIMHz and a spectral width of -1.7 nm were demonstrated. rated.
dopsd Fier DFB Laser
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 429~433
A study of the tunable fiber DFB laser using PZT-stretcher is presented. The device has an laser ocsillator by using a fiber Bragg grating at 1559.4 nm written directly into a 3-cm long
doped fiber. Post UV-exposure method to provide the necessary phase shift is used for a single mode operation. The device shows the single mode operation of
output power and has a narrow linewidth of 35 kHz. The lasing wavelength of the laser can be tuned in a range of 3 nm by stretching the grating.rating.
Operation characteristics of a diode side-pumped, high power Nd:YAG laser
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 434~440
We fabricated a high power Nd:YAG laser pumped by a 1 kW diode laser with a Lambertian-type diffusive reflector. Maximum cw power of 500 W with a slope efficiency of 49%, which corresponds to an optical efficiency of 46.7%, was obtained from a short linear resonator when a 5 mm rod was used. The efficiencies decreased when a 6 mm rod was used, due to the poor quality of the absorption distribution in the rod. The measured beam quality factor of 70, which is slightly smaller than the value calculated from the measured thermal focal lengths, shows that the absorption distribution in the rod is fairly uniform. iform.
The description of wigner function and density matrix by computer tomograph
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 441~446
Wigner functions and density matrices are computer simulated for various quantum mechanical states of light. Wigner function and density matrices are evaluated by filtered back projection which includes inverse Radon transform from the distribution function of the photocurrents, which are calculated in the balanced homodyne detection scheme. The density matrix is also directly obtained by using the pattern function from the simulated phase independent photocurrent distribution function. ction.
BER improvement of digital holographic optical memory system using an adaptive squalizer
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 447~451
In this paper, an adaptive equalizer which has been widely used in communication channel and high-density storage system was adopted to mitigate ISI and improve BER generated during storage and retrieval process of the digital holographic memory system. Our experimental results show that the BER performance with an adaptive equalizer is improved about 19.6% on average compared to the binary-decision process by global thresholding. lding.
Signl processing method and diagnostic algorithm for arterial oxygen-saturation measument
Korean Journal of Optics and Photonics, volume 11, issue 6, 2000, Pages 452~456
A measurement unit and signal processing algorithm have been developed for predicting arterial oxygen saturation noninvasively. The measurement set-up was composed of a probe including light source and photodetector, optical signal processing section, LED driving circuit, PC interface software for data acquisition and data processing software. Light from the LED's was irradiated onto the finger nail bed and transmitted light was measured at different wavelengths. An effective baseline correction method was developed and measured data were analyzed by using various data processing methods and prediction algOlithms. For performance evaluation, a pulse oximeter simulator (Bio- Tek Instrument Inc.) was used as reference. The best performance in terms of the correlation coefficient and the standard deviation was obtained under the following conditions; when the arterial signals were computed in terms of area rather than peak-valley difference, and when the algorithm calculating by
value for pulsation waveform was used. In in vivo test, prediction was improved when the developed baseline correction method was used. In addition, wavelengths of 660 nm and 940 nm provided better linearity and precision than wavelengths of 660 nm and 805 nm. 05 nm.