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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 7, Issue 4 - Dec 1996
Volume 7, Issue 3 - Sep 1996
Volume 7, Issue 2 - Jun 1996
Volume 7, Issue 1 - Mar 1996
Selecting the target year
The average ray crossing position and the best focus
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 299~304
We numerically determined the direction of ray and the average ray-crossing position from the shape of the wavefront on the exit pupil of optical system which had aberrations and apodized aperture. This position was calculated easier and closer to the position of the maximum intensity than that calculated by Safa's method when the aberration is greater than about 2λ.
Generalization of equivalent lens conversion and third order aberration formulae of the generalized equivalent lens system
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 305~313
Lens design method by using equivalent lenses was already introduced, but the method has a limitaion that all lenses should be in the air. Therefore, we often get improper solution in designing cemented lenses. In this study, the lens conversion from thick lens to equivalent lens and its reversal was generalized without any preconditions, and the third order aberration fomulrae were derived for the generalized equivalent lens system. The generalized equivalent lens conversion were applied to typical cemented doublet and triplet, and they show that the third order aberrations of the generalized equivalent lenses have better agreements with their corresponding thick lenses than the previous conversion method.
A new analysis on the bleaching mechanism and the catalysis of exposure in holographic diffraction grating fabricated with silver salt
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 314~321
In this paper, the chemical process of each step in fabricating the holographic phase diffraction grating with silver salt sensitive materials has been studied in detail. A new analysis of the bleaching methods have been made through the study. The result shows that among the types of bleaching methods, the reversal bleach can not be reacted chemically. And the experiments about the chemical reactions, the characteristics of the reaction products and the refractive modulation types by the bleaching methods have been done to prove the theory. It is investigated that the exposure acts as the catalyst of developing reaction and affects the developing reaction time conspicuously. At the optimum developing reaction times, which could be taken from the experiments, the holographic diffraction gratings with high diffraction efficiency over 70% could be obtained in the range of the exposure quantity 50~350 [
]. From the experiments about the correlation of the chemical processing conditions of the composition of developers, the exposure, and the developing reaction time, it has proved that the enhancement of the diffraction efficiency is impossible in the limited exposure energy and conventional constant chemical reaction time.
Sampling theory and widening of the viewing area for holographic stereograms
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 322~327
Unlike holograms of real objects, holographic stereograms(HS) are made using a relatively small number of synthesized 2D images. The influence of aliasing artifacts caused by insufficient or improper sampling is presented, and a new sampling theory is proposed, which is used to making holographic stereograms. Also, the optical system for extension of viewing distance and viewing zone is proposed. Results of this analysis can be applied to design normal holographic stereograms and computer based holographic stereograms.
Combined binary phase holograms for free-space optical interconnection
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 328~332
We have developed a combined binary-phase hologram (CBPH) consisting of two binary phase holograms. The CBPH can be effectively used for optical interconnection and image processing by suppressing unwanted images of a conventional binary-phase hologram. The theory and properties of the CBPH and experimental results are presented.
Planar integrated optics for implementation of fractional fourier transform
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 333~340
We have implemented a planar integrated optics for the fractional Fourier transform (FRT) which has recently been developed as a generalized form of the conventional Fourier transform. FRT optical systems provide versatile tools for analyzing signals and designing hardwares, but require high accuracy and stability in the arrangement of optical components because of their shift-variant characteristic. The planar optical FRT setup composed of free-space optical components integrated on a single glass block makes the FRT of 2-dimensional(2-D) input patterns through the 3-D glass-space. Therefore, taking advantage of the compactness, easy alignment and thermal/mechanical stability, the planar optics can provide a useful approach to realizing an optical fractional correlation system in a practical way. In the experiment, we have obtained accurate FRT results by using the planar integrated optics with 4 different fractional orders of 0.25, 0.5, 0.75, and 1.0.
Measurement of the coherence time of the light from a quasi-thermal source
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 341~347
The photocount distribution from a quasi-thermal light source, a moving ground glass disk (surface roughness; 9
) illuminated by a well-stabilized He-Ne laser, is measured by a photon counting system, and analyzed with theoretical calculations. The distribution approaches the Poisson distribution for the long coherence time
compared to the measuring time T. The coherence time
of the quasi-thermal source can be changed by controlling the velocity v of the motor driving the glass disk. By the comparison of experimental results and theory for the condition of T/
>>1, the coherence time
of the quasi-thermal source is turned out to be in the range of 31.43
according to the circumferential velocity of the disk, and compared with the simple calculation of
Precision and accuracy of CARS spectrometer for instantaneous temperature measurement
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 348~356
A mobile CARS spectrometer is constructed to measure the instantaneous temperature of gases, of which software include the quick fit methods and a least square fitting method to obtain temperatures from the spectra. Two quick-fit-methods give smaller variance of temperatures than the least square fitting method even though they consume much shorter time to yield temperatures. The precision and accuracy of CARS temperature is measured in the graphite tube blackbody furnace in reference to a radiation pyrometer. The accuracy of the CARS temperature is
2% from 1000K to 2400K and the precision is
35K at 1600K with the most accurate quick-fit-method. As a demonstration of the instantaneous measurement, the spectrometer is applied for measurement of the turbulent combustion at a certain condition. eograms(HS) are made using a relatively small number of synthesized 2D images. The influence of aliasing artifacts caused by insufficient or improper sampling is presented, and a new sampling theory is proposed, which is used to making holographic stereograms. Also, the optical system for extension of viewing distance and viewing zone is proposed. Results of this analysis can be applied to design normal holographic stereograms and computer based holographic stereograms.
Determination of the complex refractive index and thickness of MNA/PMMA thin film
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 357~362
The thickness and the spectrum of the complex refractive index in the region 1.5~4.5 eV, of an MNA/PMMA thin film fabricated by spin casting are determined. The film thickness and the refractive index in its transparent region is calculated by modeling the spectroscopic ellipsometry data. The extinction coefficient spectrum is obtained from the absorption spectrum in its non-transparent region. The best fit oscillator parameters of the classical Lorentz oscillator and a quantum mechanical oscillator are found. The complex refractive index spectrum by these oscillators are compared. The present technique can be applied to get the thickness and the complex refractive index of unknown polymer films and thus it will be useful in optical characterization of those films.
Measurement of elastic constants of single crystal
by using brillouin scattering experiment
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 363~369
We have performed Brillouin scattering experiments to investigate the elastic properties of tetragonal symmetry single crystal
and could determine the value of birefringence as well as the whole elastic constants. As a result,
Design of the nonlinearly chirped grating for broadly tunable semiconductor lasers
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 370~374
A Superstructure Grating(SSG) Distributed-Bragg-Reflector(DBR) laser has a broad tuning range with a good mode suppression ratio. However, gaps of channel are observed in the wavelength-tuning characteristics of an SSGDBR laser which employs linearly-chirped DBR mirrors. We found by numerical simulation that the gaps may be attributed to the nonuniform reflection-peak heights of a linearly-chirped DBR mirrors. We propose a nonlinearly chirped grating DBR mirror structure that makes reflection-peak heights almost uniform. Therefore a nonlinearly chirped grating structure can be employed in an extended tuning range semiconductor laser to achieve gap-free tuning and low threshold current operation simultaneously.
The optimum design of InGaAsP/InP RWG MQW-LD
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 375~385
Recently interest in the fabrication of LD operated by low current is gradually increasing as fabrication techniques of MQW-LD are progressed. In this viewpoint, theoretical estimation for decreasing the amount of threshold current will be helpful to design and make LD in case that active layer of conventional bulk type RWG-LD structure is replaced with MQW structure. Therefore, the optimum design condition of RWG MQW-LD was obtained from theoretical analysis in order to operate in the weakly index-guided LD and low threshold current. The lateral effective index step has been obtained in RWG MQW-LD structure. Waveguide mechanism including this index step has been investigated by solving the carrier diffusion equation and lateral wave equation. From these theoretical results, the optimum design condition of RWG MQW-LD have been suggested.
Performance Comparison Between Harmonically Mode-Locked Ring and Figure-of-Eight Type Fiber Lasers
Kim Kyong Hon ; Lee Hak Kyu ; Min-Yong Jeon ; El-Hang Lee ; Cheol Soon Song ; Ki Un NamKoong ;
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 386~389
We report on comparative results obtained from harmonically mode-locked laser operations of ring-type and figure-of-eight(F8) type erbium-doped fiber lasers by using a directional-coupler type electro-optic modulator as an active mode-locker. The mode-locked and transform-limited pulses of 10.6 ps width were obtained at harmonics of the fundamental cavity frequency with the F8 type laser while mode-locked laser pulses greater than 15 ps were achieved with the ring type laser.
Output characteristics of a pulsed Ti:sapphire laser
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 390~396
A pulsed Ti : sapphire laser with a Z-folded cavity, which was pumped by a frequency-doubled Nd : YAG laser, was developed. A laser output energy of 822
J with a pulsewidth of 5 ns and an output efficiency of 27.4% was obtained at a center wavelength of 790 nm using an output coupler of 18% reflectance. The slope efficiency was 35%. The output beam diameter was 0.9 mm, and the divergence angle was 1.8 mrad. The spectrum tunability was about 120 nm from 740 nm to 860 nm with a FWHM of 90 nm at an 18% output coupler and a pumping energy of 3 mJ.
Output characteristics of 1kHz high repetition rate excimer laser
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 397~402
A compact excimer laser was developed with coaxial type which the one line cross flow fan is only used. At 1 kHz repetitive operation, average power of KrF laser is 56 watt. In this paper, Design parameter and CR characteristic are investigated for attainment of the compact 1 kHz excimer laser. We have obtained overall efficiency of 1.2% with KrF laser gas. At this time, CR and the variation of laser output are 2.97,
9%. Laser gas volume and active volume are 10 liter, 1.8(H)
30(L)=64.8 ㎤, respectively.
Theoretical Description of All-Optical Switching Phenomena Involving Coupled Gap Solitons
Lee, Sangjae ;
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 403~413
We study the propagation of two pulses with orthogonal linear polarizations in a nonlinear periodic dielectric structure with
nonlinearity. Using an envelope- function approach, we derive the coupled nonlinear Schrodinger equations governing the spatio-temporal evolutions of the two orthogonally polarized modes in a nonlinear periodic structure. We then find their solitary-wave solutions referred to as coupled gap solitons. We show that two orthogonally polarized pulses can co-propagate as a coupled gap soliton through a nonlinear periodic structure while each pulse alone will be strongly reflected due to the Bragg reflection. Based on the results, we present an all-optical switching scheme which has a novel architecture and principle. We also study the stability of coupled gap solitons to find the dragging phenomena in a nonlinear birefringent periodic medium.
Polymeric digital optical switch based on photobleached waveguides
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 414~418
An electro-optic polymer digital optical switch was fabricated by using a photobleached waveguide and a self-aligned electrode. It features wavelength insensitive operation, fabrication tolerance and flexible design. And its possible advantages include low coupling losses to the fibers and wide bandwidths. For improving its switching performance, the guided mode profiles of the photobleached waveguides were controlled by photobleaching times to achieve optimized coupling in the branch. And the self-aligned electrode was employed to achieve both efficient overlap of the optical and electric fields and easy introduction of the adiabatically tapered electrodes. The measured crosstalks were better than -21dB at 1.32
, and the extinction ratios of each output port were also more than 20 dB.
Characteristics of fiber-optic current sensors using perpendicular coil formers
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 419~427
Thermally-stabilized fiber-optic current sensors are proposed and demonstrated. The sensor head is made of two coil formers combined perpendicularly. In this sensor head, bending-induced birefringences can be reduced to the level much smaller than those of the single former type because the eigen-axes of the two perpendicular coil formers are made orthogonal to each other. Moreover, thermal variation of the birefringence is also expected to be minimized by the orthogonality of the two polarization eigen-axes. We changed the temperature slowly in the range of 20~45
during 100 minutes. The overall linearity of the sensor is better than 1.2% in the range of 0~1000A. The long-term fluctuation of the sensor is less than 1% when measured for 3 hours at 500A and room temperature. Two orthogonally-polarized laser diodes are combined together to make the incident beam unpolarized. In the signal processing, the signals are separated by two parts and normalized respectively, which minimize the efects of optical fluctuations coming from sources, connectors, etc.
Transmission of 10Gb/s signal over 200km of non-dispersion shifted fiber by using mid-span spectral inversion
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 428~433
We have demonstrated 200 km non-dispersion shifted fiber(NDSF) transmission of 10 Gb/s signal by using mid-span spectral inversion(MSSI) method as a dispersion compensation technique. We have used four-wave mixing process in dispersion shifted fiber(DSF) to generate a spectrum inverted signal. The spectral inversion efficiency of -26.7dB and signal to noise ratio of 23.0 dB have been achieved. The measured sensitivities at
bit error rates (BER) were -28.0 dBm in back to back configuration and -27.0 dBm after transmission of 200 km NDSF.
Influence of truncated gaussian beam on read-out signal in optical disc
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 434~439
To investigate influence of the incident beams which have the truncated Gaussian amplitude and of the shapes of bump on read-out signal is an optical disc, and the point spread function on bump, the scalar diffraction theory is used in this paper. We consider the truncated Gaussian amplitudes which are
=0, 0.5, 1.5, and 2.5, the height of bump which is given by
, and the phase height of bump which is then given by
. We also consider the shapes of the bump which are a rectangular shape, a frustoconical shape, and a conical shape. It is shown that as the truncation of incident beam reduces the radius of central spot on bump decreases, the maximum value of read-out signal increases, and that the size of bump decreases. From these results, we get better read-out signal and the reduced cross-talk in optical disc when the truncation of incident beam reduces. Therefore a laser beam having less truncated Gaussian amplitude may useful for an actual optical disc.
An InGaAs/InAlAs multi-quantum well (MQW) avalanche photodiode (APD) with a spacer layer showing low dark current and high speed
Korean Journal of Optics and Photonics, volume 7, issue 4, 1996, Pages 440~444
In this paper, we report an InGaAs/InAlAs multi-quantum well (MQW) avalanche photodiode (APD) showing a performance suitable for 10 Gbps lightwave communications. In designing the device, emphasis is given on the effect of indiffusion of Be dopant from the highly doped field layer into the MQW multiplication region. It is found that a small amount of diffusion can alter the dark current and gain characteristics of the device significantly. A spacer used to restrain such indiffusion is shown effective in reducing dark current (500 nA at a gain of 10) while maintaining a high bandwidth (10 GHz at a gain of 10) devices grown by molecular beam epitaxy.