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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Korean Journal of Optics and Photonics
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Journal DOI :
Optical Society of Korea
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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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Effect of scratches on optical connector interface surface on the insertion loss
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 287~292
DOI : 10.3807/KJOP.2004.15.4.287
This paper presents the effect of scratches on an optical connector interface surface on the insertion loss of optical connectors. We propose a model for calculating the insertion loss of optical connectors. The model is expressed in terms of geometrical parameters of scratches assuming that the transmission coefficient of a light wave on the scratch surfaces is linearly varied as a function of scratch depth. Geometrical parameters of scratches such as location, width, and depth of scratches are measured using 3D optical interferometry surface profiler. We obtain the equation of the transmission coefficient in terms of scratch depth comparing the experimental insertion loss data to the insertion loss data using the model presented in this paper. Using the model and the equation of the transmission coefficient presented in this paper, we present the results of the insertion loss of optical connectors for various geometrical parameters of scratches. Scratches which are located at longer than two times the core radius from the center of the core show negligible effect on the insertion loss of optical connectors.
Effect of wing width and thickness on the polarization characteristics of vertical directional couplers using the Double-Sided Deep-Ridge waveguide structure
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 293~298
DOI : 10.3807/KJOP.2004.15.4.293
We investigate the effect of the wing width and thickness of a Double-Sided Deep-Ridge(DSDR) vertical directional coupler on the coupling length dependent on the polarization, We have found that the DSDR vertical directional coupler without a wing does not have polarization independent coupling lengths. The variation of the coupling length of TE and TM modes and the difference between the coupling lengths of the two modes are negligible as the wing width increases beyond the specific wing width for the same wing thickness. Thus, we can see that a DSDR vertical directional coupler has a wing width larger than the minimum wing width to obtain the polarization independent coupling length. The minimum wing width increases as the wing thickness increases for the same core thickness and as the core thickness decreases for the same wing width. Also, we have found that the minimum wing thickness is determined by the core thickness and the minimum wing thickness decreases as the core thickness increases.
Realization of the multi-phase level CGH according to the multi-channel encoding method using a PAL-SLM
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 299~308
DOI : 10.3807/KJOP.2004.15.4.299
We proposed more efficient encoding methods that can design a multi-channel multi-level phase only computer-generated hologram(CGH) that can reconstruct many objects simultaneously without a conjugate image. We used a fabrication technique for the pixel oriented CGH for designing the pattern of the proposed multi-channel CGH. We investigated the difference of the optical efficiency(η), mean square error(MSE) and signal-to-noise ratio(SNR) of multi-channel CGHs that were designed by three kinds of encoding methods according to the number of quantization phase levels, and we estimated the performance of the pattern of the proposed multi-channel CGH. Generally, as the number of input objects` reference patterns stored in the CGH is increased, the reconstruction quality of the CGH is degraded. But we observed through computer simulation that the diffraction efficiency of the 1-ch CGH is 70%, and those of the 2-ch, 4-ch, 8-ch CGHs are 62%, 62% and 63%. Therefore we found that the diffraction efficiencies of the multi-channel CGHs using the newly proposed encoding method are similar to that of 1-ch CGH. We implemented the CGH optically using a liquid crystal spatial light phase modulator that consisted of a PAL-SLM efficiently coupled with a XGA type LCD by an optical lens and an LD for illuminating the LCD. We discussed the output images that are reconstructed from the PAL-SLM.
Nanofabrication of InP/InGaAsP 2D photonic crystals using maskless laser holographic method
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 309~312
DOI : 10.3807/KJOP.2004.15.4.309
Two-dimensionally arrayed nanocolumn lattices were fabricated by using double-exposure laser holographic method. The hexagonal lattice was formed by rotating the sample with 60 degree while the square lattice by 90 degree before the second laser-exposure. The size and period of nanocolumns could be controlled accurately from 125 to 145 nm in diameter and 220 to 290 nm in period for square lattice by changing the incident angle of laser beam. The reactive ion etching for a typical time of 30 min using CH
plasma enhanced the aspect-ratio by more than 1.5 with a slight increase of the bottom width of columns.
Diffraction grating interferometer for null testing of aspheric surface with binary amplitude CGH
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 313~320
DOI : 10.3807/KJOP.2004.15.4.313
We present a null testing method fer aspheric surfaces, utilizing a phase-shifting diffraction grating interferometer along with a binary amplitude computer generated hologram (CGH). The binary amplitude CGH is designed to compensate for the wavefront between a point source and the aspheric surface under test. The fringe visibility of the grating interferometer is controlled easily by selecting suitable grating diffraction orders for the measurement and reference wavefronts or by optimizing the groove shape of the grating used. The binary amplitude CGH is designed by numerical analysis of ray tracing and fabricated using e-beam lithography for autostigmatic testing. Experimental results of a large-scale aspheric mirror surface are discussed to verify the measurement performance of the proposed diffraction grating interferometer.
Nonlinear characteristics of photodetectors for optical fiber power measurements
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 321~324
DOI : 10.3807/KJOP.2004.15.4.321
We have composed an experimental system using the superposition method to measure the nonlinearity of photodetectors for optical fiber power measurements. Also we have measured the nonlinearity of a high power detector and of a low power detector. The two detectors have shown good linearity within 0.01% and 0.02%, respectively, in the 50 ㏈ dynamic range. These detectors are used as reference detectors in optical fiber characteristics measurements.
Fabrication of reflectometer for vacuum ultraviolet spectral characteristic measurements of optical component
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 325~330
DOI : 10.3807/KJOP.2004.15.4.325
We fabricated a vacuum ultraviolet spectre-reflectometer which consists of a deuterium light source, a vacuum monochromator, and a sample chamber and detector module. The operation was performed in the ultraviolet spectral ranges between 115 nm and 330 nm at the vacuum pressure of 3.0
Pa. The wavelength of the vacuum monochromator was calibrated with the line spectrum of a low pressure Mercury lamp of 253.652 nm and 184.95 nm wavelengths, and its resolution was 0.012 nm, and the precision of wavelength was
0.03 nm. With this reflectometer and a deuterium lamp, we measured the spectral regular transmittance and reflectance of materials(MgF
, Sapphire) used as optical components over the spectral range between 115 nm and 230 nm.
Phase change on reflection in a white-light interferometer as polarization is changes
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 331~336
DOI : 10.3807/KJOP.2004.15.4.331
The phase change due to the reflection from target surfaces in a white-light interferometer induces measurement errors when target surfaces are composed of dissimilar materials. We prove that this phase change on reflection as the polarization of the white-light changes causes a shift of both envelope peak position and fringe peak position of several tens of nanometers as the polarization of the white-light changes. In addition, we propose a new equation for white-light interference fringes depending on the polarization of the source.
Power stabilization of a slab CO
laser by using the Opto-Hertzian effect
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 337~342
DOI : 10.3807/KJOP.2004.15.4.337
Laser optical power stabilization of a radio frequency excited
slab laser using the opto-Hertzian effect generated from the laser itself is achieved on the peak of the Doppler broadened gain curve. The opto-Hertzian signal was generated by a modulation of the optical flux circulating inside the laser cavity from a variation in the cavity length caused by the vibrations of the PZT. The opto-Hertzian signal is directly coupled from a RE discharge chamber via a loop antenna into a detector and applied to a lock-in stabilizer as an reference signal. The power stability of an RF excited slab laser is estimated to be better then 0.2%.
The radio-frequency excited matrix waveguide CO
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 343~348
DOI : 10.3807/KJOP.2004.15.4.343
We report the design and basic operating characteristics of an radio frequency excited waveguide
laser. Four picecs of waveguide channels are placed in one laser cavity to increase a power per unit length with the form of a 2
2 matrix. Four independent optical outputs are measured from the front of output coupler, and these beams are combined to a Gaussian mode beam far from the output coupler. A 12 W output power has been obtained with
: He : Xe
Design, Fabrication and Frequency Analysis of Transmitter Optical Sub-assembly for a 10 Gb/s XFP Transceiver
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 349~354
DOI : 10.3807/KJOP.2004.15.4.349
As a transmitter sub-assembly in the XFP(10 Gb/s Small Form Factor Pluggable) transceiver module, a transmitter optical sub-assembly(TOSA) is designed, fabricated and characterized in view of electrical and thermal performances. For a low-cost and compact packaging TOSA, the bias-tee and the matching resistor are monolithically integrated on the AlN sub-mount and a newly designed coplanar waveguide is drawn in the TO-stem. All optoelectronic components packaged in the TOSA are modeled by the equivalent circuit, which helps to improve and characterize the TOSA performance. The fabricated TOSA shows the -3㏈ bandwidth as high as 11 GHz at an elevated temperature of 85
Correlation of biophoton emission between left and right hands, and palm and back of hands
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 355~360
DOI : 10.3807/KJOP.2004.15.4.355
Biophotons from three healthy subject`s hands were measured every Friday for one year. The correlation coefficients between the left and right palms were found to be 9.0, and a similar value was also obtained between the left and right back of hands. However, the correlations between the palm and back of a hand turned out to be low, on the average only 0.5. These results are consistent with the result of Zhang`s
production rate experiments on the acupuncture points. The high correlation between the left and right, and the low correlation between the palm and back are interpreted according to the acupuncture theory of meridians. The palm and the back correspond to the yin and yang meridians, respectively. And their behaviors are rather opposite, thus they show low correlations.
Spot marking of the multilayer thin films by Nd:YAG laser
Kim, Hyun-Jin ; Shin, Yong-Jin ;
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 361~368
DOI : 10.3807/KJOP.2004.15.4.361
We separated the multilayer structure of CD-R(compact disk-recordable) and investigated optimal spot marking conditions and physical and chemical transitions in response to various laser beam energh levels. Spot marking(80
spot size) was produced on the surface of each layer using a Q-switched Nd:YAG laser between 27 mJ and 373mJ. By investigating resulting pit formation with Optical Microscopy(OM) and Optical Coherence Tomography(OCT), we analyzed the formation process of spot marking in the multilayer structure of different chemical composition. The localized heating of the substrate in the multilayer thin film caused the short temporal thermal expansion, and absorbed optical energy between reflective and dye interfaces melted dye and increased the volume. During the cooling phase, formation of pit and surrounding rim can be explained by three distinct processes; effect of surface tension, evaporation by spontaneous temperature increase due to laser energy, and mass flow from the recoil pressure. Our results shows that the spot marking formation process in the multilayer thin film is closely related to the layers` physical, chemical, and optical properties, such as surface tension, melt viscosity, layer thickness, and chemical composition.
A widely tunable sampled-grating distributed feedback laser diode integrated with sampled-grating distributed bragg reflector
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 369~374
DOI : 10.3807/KJOP.2004.15.4.369
In this paper, we propose a new tunable laser diode structure. The laser diode consists of a sampled-grating distributed feedback laser diode monolithically integrated with a sampled-grating distributed-Brags-Reflector. For a specific design, the possibility of continuous/discrete wavelength tuning over 27nm is confirmed by a numerical analysis using a split-step time domain model. Because the laser diode can be directly coupled with optical fiber without the intervention of the passive section, the laser diode exhibits higher output power than the conventional laser diode.
three-waveguide type traveling-wave optical modulator; outer fed, anti-symmetrical Detuning
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 375~384
DOI : 10.3807/KJOP.2004.15.4.375
Switching phenomenon of a three-waveguide optical coupler was analyzed by using the coupled mode theory, and the coupling-length of the device was calculated by means of the FDM. CPW traveling-wave electrodes were designed by the CMM and SOR simulation techniques so as to satisfy the conditions of phase-velocity and impedance matching. Traveling-wave modulators were fabricated on a z-cut LiNbO
substrate. Ti was in-diffused in LiNbO
to make waveguides and Au electrodes were built on the waveguides by the electroplating technique. Insertion loss and switching voltage of the optical modulator were about 4 ㏈ and 15.6V. Network analyzer was used to obtain S parameters and corresponding RF response. From the measurement, parameters of the traveling-wave electrodes were extracted as such Z
A 4-bit optical true time-delay for phased array antennas using 2×2 optical MEMS switches and fiber-optic delay lines
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 385~390
DOI : 10.3807/KJOP.2004.15.4.385
In this paper, we designed a 4-bit optical true time-delay(TTD) for phased array antennas(PAAs), which is composed of a wavelength-fixed optical source, 2
2 optical MEMS switches, and fiber-optic delay lines. A 4-bit TTD with a unit time delay difference of 6 ps for 10-GHz PAAs has been implemented. Measurement results on time delay show an error of -0.4 ps at maximum, corresponding to a radiation angle error of less than 1.63
. Thus, the TTD implemented in this research performs in excellent agreement with theory. Each TTD line, composed of MEMS switches and fiber-optic delay lines, connected to the corresponding antenna element has insertion loss in between 1.36 ㏈ and 2.40 ㏈ depending upon the setup of the switches. On the other hand, the insertion loss difference between TTD lines was 0.32 ㏈ at maximum for a fixed radiation angle. The TTD structure proposed in this paper might be more reliable and economical than those previously proposed using tunable wavelength sources if proper power equalization either with gain control of RF amplifiers or variable attenuators is achieved.
Optical alignment of a high-resolution optical earth observation camera for small satellites
Kim, Eugene D. ; Park, Young-Wan ; Kang, Myung-Seok ; Kim, Ee-Eul ; Yang, Ho-Soon ;
Korean Journal of Optics and Photonics, volume 15, issue 4, 2004, Pages 391~396
DOI : 10.3807/KJOP.2004.15.4.391
Spaceborne earth observation or astronomical payloads often use Cassegrain-type telescopes due to the limits in mass and volume. Precision optical alignment of such a telescope is vital to the success of the mission. This paper describes the simulated optical alignment methods using interferograms, wavefront error, and reverse-optimization method for different levels of alignment accuracy. It concludes with the alignment experiment results of a Cassegrain type spaceborne camera with 300mm entrance pupil diameter.