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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 5, Issue 4 - Dec 1994
Volume 5, Issue 3 - Sep 1994
Volume 5, Issue 2 - Jun 1994
Volume 5, Issue 1 - Mar 1994
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3-D Profilometry by Phase Shifting Profilometry
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 191~197
We investigated the properties of various methods of 3 dimensional profilometry to choose the phase shifting technique for the reconstruction of the shape of a given specimen. The pattern was generated by a Twyman-Green interferometer and a PZT was used to shift the fringes on the target surface. The shape was calculated with Hariharan algorithm within the uncertainty of a scaling factor. The optical noise inherent in the laser source was observed to influence the final outcome to a great extent and the need for an exact calibration was noted. noted.
Measurement of Long Radius of Curvature by Using Bidirectional Shearing Interferometer
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 198~203
An improved method for the measuement of very long radius of curvature by using a bidirectional shearing interferometer in a noncollimated light beam is given. This method can be used for both lenses and surfaces with positive or negative power. Detailed analyses for optical arrangements and achievable accuracy are presented.sented.
Design of micro lens array
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 204~211
Micro array lens systems are designed for a faximile or copy machine. The array type is hexagonal. Diameter of a lens is 0.16 mm and the distance of the center of the nearest neighbor is 0.192 mm. The magnitude of the lens system is 1:1. Working distane is 10.55 mm and the spot size is less than 0.04 mm radius on axis and 0.20 mm off-axis in case of single layer system. Working distance is 7.90 mm and the spot size is less than 0.07 mm radius on axis and 0.09 mm radius off axis in case of double layer system. Performance of single layer micro array lens system and double layer micro array lens system are compared with the characteristics of the ray fans.y fans.
A Serial-Parallel Scanner Optics for Thermal Imaging System
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 212~216
We have designed and constructed a scanner optics for thermal imaging system operating in 8 - 12 /lfll band. The scanner consists of rotating polygon and oscillating mirror for serial-parallel scan using 5 elements SPRITE HgCdTe. A spherical mirror is used for scan relay mirror to minimize size of the scan mirrors and pupil aberration. The scanner has
wide scan field of view and the calculated diffraction MTF shows diffraction limited performance. As a result we have obtained high resolution thermal image. image.
Noise Elimination of Speckle Fringe Phasemap
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 217~224
The combination of both phase-shifting convolution and 2-bit quantization smoothing filter was used to reduce speckle noise from saw-tooth speckle fringes phase map, obtained in phase-shifting speckle interferometer. The phase-shifting convolution showed the noise reduction capability of speckle fringe without destroying edge information across 271 jump. Also, it was shown that the 2-bit quantization smoothing filter was superior to average, low-pass filter and median filter in speeding up smoothing process and enhancing SIN ratio. Finally, a path dependent unwrapping algorithm was used to unwrap a noise reduced 271 modulo speckle phasemap. semap.
Design and Fabrication of Holographic Head-up Display System
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 225~230
Main parameters and equations necessary for developing the holographic HUD are investigated. Air reflection recording method of obtaining good holographic reflection filters with minimized interference pattern noises is presented. Especially, a new method of correcting the center wavelength shift which takes place after the processing of the DCG film is suggested.gested.
Spectroscopic methods for the analysis of tandem fabry-perot interferometer
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 231~237
We present spectroscopic methods to analyze the structural parameters of tandem Fabry-Perot interferometers. By using laser beams of two different frequencies by several tens of GHz, we investigated the cavity spacings of the two interferometers and ways to measure and to find the limitation of the neccesary conditions between the two interferometers. All of the theoretical results has been also confirmed experimentally.ntally.
Numerical simulations on the amplitude and phase dependent propagation characteristics of dark solitons
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 238~244
We numerically studied on the dark solitons propagation for initial amplitude and phase shapes in the normalized nonlinear Schr dinger equation(NLSE) which describes the propagations of optical solitons. As the propagation distance increases, odd dark solitons evolve into a black soliton and pairs of gray solitons which have a different sign of blackness, and even dark solitons evolve into pairs of gray solitons without black solitons. When there exists a black soliton and a gray soliton, even though the initial amplitude shape is same, the sign of blackness of a gray solitons determines whether they would collide or not. We could see that the energy of dark solitons evolve into a couple of solitons of different blackness since there exists a continuous range of dark solitons with arbitrary blackness parameter, and this phenomenon was more clearly seen from the change of phase shapes from that of amplitude shapes. hapes.
Switching and first-passage-time distributions in a two-mode ring dye laser
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 245~251
The charateristics of switching between two modes in a ring dye laser has been analyzed by the Monte-Carlo computer simulation. The effect of including pump fluctuations in the first-passage-time (FPT) distributions was compared with the distribution with the quantum fluctuation. The results show the same tendency in both cases, such as steep increases from 0 to peak an exponential decrease in long time range. However the introduction of pumping fluctuation is turned out to shorten the mean FPT. The variation of the mean FPT is examined for the various fluctuationrelated parameters. The mean FPT is lengthened when pump parameter a is increased while it is shorted when Q.
are decreased. eased.
Limitations of time resolution and spatial overlap caused by group velocity mismatch in experiments using ultrashort UV and visible optical pulses.
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 252~259
The method of calculating overlap dispersion caused by group velocity mismatch between uv and visible pulses in ultrafast pump-probe experiments is presented to discuss limitations of the time resolution and signal intensity. The calculations show arrangements using a single focusing lens shall result in undesirable time resolution and low signal intensity. Achromatic doublets result in unrealistic solutions. However, dramatic improvement in the time resolution and signal intensity is expected in the optical arrangements using separate lens for each pulse and in the arrangements using a cutoff secondary lens with a main lens. lens.
Two-photon excitation in three-level atom
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 260~265
In the three-level atom interacting with a single mode radiation field, two-photon excitation between the ground state and the upper most excited state is investigated. Using the resolvant theory, the effective resolvant, containing the ground state and the final excited state, is found and the coupling constant and the detuning being taken as parameters, the excitation mechanism is analyzed. In particular. by introducing an ensemble of effective two-level atoms, a consistent interpretation in terms of inteference phenomena is pursued. rsued.
Output Enhancement of Rhodamine 6G Dye Laser by Rhodamine 560 Energy Transfer Dye
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 266~271
The output power and the energy of Rh-6G dye laser were enhanced by the mixture of Rh-560 dye whose fluorescence spectrum was coincident with the absorption spectrum of Rh-6G. The argon filled coaxial flashlamp used for pulsed pumping and argon laser for CW pumping. The concentration of Rh-6G dye was optimized in each pumping method before Rh-560 dye was mixed in Rh-6G dye solution. In the coaxial flash lamp pumped Rh-6G laser the output energy was increased about 30% when Rh-560 was mixed at 1% of Rh-6G concentration. In the case of argon laser pumping with multiline, the output power was increased 18% at the concentration of 2.5%. In the single line laser pumping, the output power was enhanced more efficiently. The power enhancements were 72% and 88% when the pumping wavelengths were 488 nm and 514.5 nm respectively. ively.
Detection of Damage of Rd6G Film Using Surface Second-Harmonic Generation
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 272~277
The damage of a thin film of Rd6G dye was probed by Surface Second-Harmonic Generation(SSHG) method. A portion of the Rd6G thin film on glass substrate was damaged by 532 nm laser beam, and the damage was probed by detecting intensity variation of SSHG. The result was confirmed through direct observation with optical microscope.oscope.
Characteristics of Visible Laser Diode and Its Injection-Locking
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 278~285
We investigated the spectral characteristics for temperature and driving current change in visible laser diode. As a result of spectrum analysis, the ratio of frequency change for temperature and driving current change were about
, 6.6 GHz/mA in the region which was not mode hopping range. Compared to the sharp mode hopping in the near IR single mode AlGaAs lasers, the visible laser diode showed relatively broad multimode operation in the mode hopping region. We performed the experiment of injection-locking characteristics analysis for visible laser diode. Locking half bandwidth(LHBW) was measured 0~5.0 GHz for
input power and it was dependent on the input power. Also, LHBW for polarization angle was dependent on the difference of polarization angle between master laser and slave laser. The phase change of injection-locked output beam of the slave laser diode as a function of the drive current was measured in the interferometer which was composed of master laser and slave laser. The ratio of phase change with the slope of 5.0~1.3 rad/mA was obtained within injection-locking range for the change of
input power. power.
Characteristics of Er-Doped Fiber Laser on Resonator Reflectivities and Pump Power
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 286~290
Lasing characteristics of an Er-doped fiber laser have been investigated at various conditions of resonator reflectivities and pump powers. Variation of the laser wavelength with various mirror reflectivities has been compared with the theoretical analysis based on absorption, gain spectra, and resonator parameters. The maximum slope efficiency of 38% was obtained with the resonator's mirror reflectivities of 100% and 4% on both sides, and the threshold powers were varied from 7.8 mW to 5.6 mW, and lasing wavelengths were varied
for 6 and 15.8 mlong Er-doped fiber, respectively, as the resonator reflectivities were changed from 0.0016 to 0.9.to 0.9.
Gain and spectra stabilization in erbium-doped fiber amplifier with optical feedback
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 291~297
A feedback loop with bandpass filter is introduced in erbium-doped fiber amplifier to clamp the amplifier gain by lasing the amplifier at a selected wavelength. The gain and the ASE (amplified spontaneous emission) output spectra are found to be independent of input signal power and pump power variation so long as the amplifier is lasing. Also they are found to be dependent only on the overall loss of the feedback loop. Even in the case of slowly modulated large signal input, signal distortion due to gain saturation is not observed.served.
The Fabrication of Microlenses by Photoresist Melting Method
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 298~303
Microlens arrays are fabricated by melting "islands" of thick photoresist on a glass substrate. Microlenses with diameters
are made. Their surface profiles are obtained by a scanning electron microscope and a mechanical surface profilometer. The wavefront of the microlenses is measured by phase-shifting techniques using a Mach-Zehnder-like configuration. Thereby wavefront errors, focal lengths. point spread functions are obtained. The microlens with the diameter of
has focal length of
and spot diameter is less than
Thermally Expanded Core Fibers for Hybrid Fiber Components
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 304~310
The use of thermally expanded core (TEe) fibers fabricated by thermal diffusion of dopants such as
in hybrid fiber components has an advantage of eliminating lenses for collimation and focusing. An electric furnace is fabricated to heat the fibers locally for the core expansion. We observed an expansion of the mode size at
wavelength by 27% after treating a section of single mode optical fiber at
for 10 hours. hours.
Fabrication and Characterization of Surface Plasmon Fiber-Optic Polarizers
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 311~318
We fabricated fiber-optic polarizers utilizing polarization selective mode coupling between the guided mode of a fiber and the surface plasmon mode supported by a thin aluminium film deposited on the polished side of a fiber. AI thin films with various thicknesses were coated onto the 633 nm, 830 nm, 1.3 fJITI single mode fibers. The maximum extinction ratio was higher than 30 dB for most of the samples and the best result was 42 dB at 90 A film thickness, with 1.3 fJITI single mode fiber. The insertion loss ranged from 0.2 dB to 1.5 dB.1.5 dB.
Impact of FWM on manchester coded DPSK WDM communication systems
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 319~325
The performance of Manchester-coded DPSK optical wavelength division multiplexing (WDM) systems using a stochastic approach is evaluated taking into account the shot noise and the four-wave mixing (FWM) caused by fiber nonlinearities. The result of Manchester-coded system is compared to conventional non-return-to-zero (NRZ) systems for DPSK modulation formats. Further, the dynamic range, defined as the ratio of the maximum input power (limited by the FWM), to the minimum input power (limited by receiver sensitivity), is evaluated. For
16 channel WDM systems, the dynamic range of DPSK Manchester coded systems shows a 2.1 dB improvement with respect to the NRZ. This result holds true for both dispersion-shifted fiber and conventional fiber; it has been obtained for 10 GHz channel spacing, 1 Gbps/channel bit rate.t rate.
Performance of long-haul optical fiber commumication system using optical amplifiers with post amplifier loss
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 326~332
Performance of soliton based long-haul optical communication system with in-line optical amplifier repeaters are evaluated numerically. To reduce the optical amplifier noise, the amplifier gain is increased and the post amplifier loss is included. By theoretical calculation with 1480 nm co propagating pump, 7 dB amplifier gain and operating the amplifier 1 dB in compression, the spontaneous emission factor can be reduced from 2.37 to 1.45 by increasing the pump power from 3.71 to 11.53 mW and increasing the post amplifier loss from 0 to 10 dB. Then, power penalty can be reduced from 4.09 to 1.20 dB for 8,000'km transmission and the maximum transmission distance is 14,890 km. ,890 km.
Fabrication and Characterization of PIN-Preamplifier Module for High Speed Optical Receiver
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 333~339
We fabricated a single mode fiber pigtailed PIN-preamplifier front-end receiver module for the high speed optical receiver. Hybrid method was used to integrate GaInAs PIN photodiode and transimpedance type GaAs preamplifier. The capacitance and the diameter of light receiving area of PIN photodiode were 0.35 pF and
respectively. The -3 dB cut-off frequency of PIN-preamplifier module was above 2 GHz, and the sensitivity of the module at 2.5 Gbps NRZ
signal was -25.2 dBm at
BER. > BER.
Fabrication and characterization of InGaAs Separate Absorption Grading Multiplication Avalache Photodiodes for 2.5 Gbps Optical Fiber Communication System
Korean Journal of Optics and Photonics, volume 5, issue 2, 1994, Pages 340~346