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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 8, Issue 6 - Dec 1997
Volume 8, Issue 5 - Oct 1997
Volume 8, Issue 4 - Aug 1997
Volume 8, Issue 3 - Jun 1997
Volume 8, Issue 2 - Apr 1997
Volume 8, Issue 1 - Feb 1997
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Self-starting phase conjugate laser in population inverted Nd:YAG
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 357~361
We report the operation of a self-starting phase conjugate laser(PCL) oscillator which compensates intracavity phase distortion. The self-starting PCL in the population inverted Nd:YAG gain media produced an output energy of 200 mJ in a 20 ns single-longitudinal-mode pulse at 10Hz. And it showed well-defined Gaussian spatial profile.
An optical phase stabilization technique for interferometric systems
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 362~365
This paper presents a new optical phase stabilization technique for interferometric such as Mach-Zehnder interferometers or Homodyne detectors. The proposed technique can lock such interferometric systems in their maximum/minimum optical outputs without using a dither signal. The phase control scheme is a modified steepest decent algorithm, and is analyzed in terms of a delta modulation approach. It is also applicable to low-repetition rate pulsed interferometric systems in which conventionally used dithering method is difficult to be applied.
Velocity selective optical pumping spectroscopy
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 366~371
We performed the velocity selective optical pumping(VSOP) spectroscopy using the rubidium atomic vapor in the room temperature. This spectroscopic technique removes the Doppler broadening by both optical pumping effect and the selection of atoms with a particular velocity. In this experiment, we used two independent lasers; one was a locked laser whose frequency was fixed and the other was a sweep laser whose frequency was tunable. The two beams were passing through the sample in the same direction unlike the conventional VSOP spectroscopy using two counter-propagating beams. We could make the velocity selective range of atoms much wider with this method than the old one.
Dependence of the time resolved anti-Stokes Raman signal on the correlation between pump and Stokes waves
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 372~376
We study the time resolved anti-Stokes Raman spectroscopy with correlated pump and Stokes waves. When only two pump waves with relative delay are incident into a Raman medium, the Stokes waves generated by stimulated Raman scattering couple with the pump waves to generate anti-Stokes signal. Since the correlation between Stokes and the pump waves are not perfect and not quantified yet, we make a simple model fot it and calculate the normalized anti-Stokes signal intensities as a function of time delay. The broadband light regarded as chaotic field.
Study of poling condition in 2 mole% MgO-doped
using second harmonic generation
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 377~381
Poling condition in 2 mol% MgO-doped
crystals is investigated by varying the amplitude of poling electric field from 3V/cm to 7V/cm. It is found that 5V/cm is the best value for the formation of single domain by analysing the characteristics of the second harmonic generation(SHG) as the function of temperature. The temperature dependence of the phase-matching profile of SHG for the crystal applied by a spatially modulated electric field is observed to be very different from the simple sinc function. The distorted profile can be consistently fitted with the numerical simulations. This shows that the crystal homogeneity can be tested by the SHG temperature phase-matching profile. In addition, the thermo birefringence coefficient and electro birefringence coefficient of SHG were measured from the temperature dependence of phase-matching profile and shifts of phase-matching temperature by appling electric field along c-axis.
Characterizations of optical properties and microstructures of composite
films fabricated by ion assisted deposition
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 382~386
films are fabricated by codeposition from two independent sources. To improve optical and mechanical properties of films, the films are prepared by ion-assisted deposition. Chemical compositions, optical properties and microstructures of the composite films were investigated. The chemical composition rates of Ti:Mg of
composite films are nonlinearly varied according to the relative deposition rate. It is found that the refractive indices of the composite films decrease with increasing
contents and can be fitted quite well with Drude's formula and that the microstructures of the composite films changes from an amorphous to crystalline with increasing
The influences of laser-induced damage threshold by the post-processing of
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 387~394
The influences of laser-induced damage threshold by the after-processing of
thin films was investigated. The samples were fabricated at the substrate temperature of
respectively, and the LIDT were measured by using Nd:YAG laser. After the processing with baking and laser conditioning of the samples, the variation of LIDT was measured. It was found that LIDT was enhanced twice by laser-conditioning process and 1.5 times by baking process. In addition, we measured the chemical properties of the thin film structure before and after the processing by using XPS.
Real-time controlled deposition of anti-reflection and high-reflection coatings for semiconductor laser
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 395~402
We have obtained the optimum thickness of anti-reflection(AR) coating on one of facets of a
InGaAsP MQW FP semiconductor laser by in-site monitoring of the light emitted from the rear facet during the film deposition on the fore facet. The optimum thickness of
thin film whose refractive index is 1.85 was found to be 188 nm. The reflectivity of the coated facet was calculated by the threshold current ratio of before and after AR coating, which was obtained from exprimental data, and it was about 2
. The results show that the output power is increased by 87% at bias current 60 mA, the slope efficiency is increased by 3.4 times, and the threshold current is increased by 2.64 times. By in-situ depositing of the
thin film HR coating on the rear facet, the output power was increased by 160% than before the AR and HR coatings, the slope efficiency was increased by 3.8 times, the threshold current was increased by 1.07 times, which is similar to the value of before AR coating. Due to the AR and HR coatings the output light power characteristics were enhanced.
Electrooptic pattern recognition system by the use of line-orientation and eigenvector features
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 403~409
We proposed a system that can perform pattern recognition based on parrallel optical feature extraction and performed experiments on this. The feature to be extracted are both 6 simple line orientations and two eigenvectors of the covariance matrix of the patterns that cannot be distinguished with the line orientation features alone. Our system consists of a feature-extraction part and a pattern-recognition part. The former that extracts the features in parallel with the multiplexed Vander Lugt filters was implemented optically, while the latter that performs the pattern recognition by the use of the extracted features was implemented in a computer. In the pattern recognition part, two methods are tested;one is to use an artificial neural network, which is trained to recognize the features directly, the other is to count the numbers of specific features simply and then to compare them with the stored reference feature numbers. We report the preliminary experimental results tested for 15 alpabet patterns with only straight line segments.
Fabrication of transducer optimized acousto optic modulator for laser projection display
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 410~414
Laser projection display is a full color display system for large area. In this system, laser beams are modulated at acousto optic modulators(AOM) according to the video signal. AOM consists of a
crystal and a
transducer. We calculated the acoustic wave propagating from transducer to acousto optic media and made AOM by the calculated results. We compared calculated results with fabricated AOM by measuring modulation efficiency at various frequency. The modulation efficiency of AOM is 85% at the carrier frequency of 144MHz and the rise time is 41.5 ns.
Fiber Bragg grating sensor using polarization-maintaining fiber
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 415~419
A novel fiber optic sensor is demonstrated using a FBG in PM(Polarization-Maintaining) fiber. Gratings have been written in a Bow-Tie type fiber using the phase mask. The operation of the sensor simply involves monitoring back-reflected Bragg wavelengths from the grating. Since PM fiber has two principal semi-axes with two indices of refraction, two Bragg wavelengths were observed. We have observed the position of Bragg wavelengths for PM FBG shifted simultaneously by either applying the longitudinal strain or temperature change. The wavelength sensitivity of 1.2pm/
about a longitudinal strain and the wavelength sensitivity of 11.4pm/
about a temperature have been experimentally achieved. The wavelength sensitivity of both longitudinal strain and temperature are approximately same with the reported values for the single mode FBG. On the other hand, the change of separation between Bragg wavelengths was observed by the applying transverse stress. We observed that the separation between two Bragg wavelengths is proportional to the applied transverse stress. The wavelength sensitivity of 14.6 pm/N about a transverse stress has been achieved. We have demonstrated PM FBG sensors can measure the transverse stress independently from the effects of temperature.
Properties of an optical interaction-free measurement system for nonopaque objects
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 420~425
An interaction-free measurement system with the polarization-based Mach-Zehnder interferometer structure is described. Properties of the system are investigated especially for nonopaque objects. Here it is shown that the interaction-free measurement of such objects is possible. Our system, whose detection efficiency corresponds to 70% in the sense of interaction-free measurement, was implemented and preliminary experiments were performed to show its feasibility.
Implementation of a closed-loop signal processor for the open-loop FOG
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 426~430
A signal processor is implemented to verify the possibility of a closed-loop signal processing for the open-loop fiber-optic gyroscope (FOG). As an all-digital implementation of phase tracking scheme, it does analog-to digital conversion of the detector output and signal processing all-digitally thereafter for a noise-immune FOG signal processor. It has a potential of 36-bits resolution in the
range which is best in the number and sets no limit in the magnitude of the phase shift. The new signal processor was tested on an all-fiber gyroscope and turned out to have a resolution of
rad(corresponds to 0.74 deg/hr), which is good enough to measure the Earth's rotation rate.
Planar-optical interconnections by using a novel gradient-index substrate
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 431~437
A gradient-index (GRIN) substrate is proposed as a novel signal propagation medium of planar optics. The GRIN substrate provides planar-optics designers not only a 3-dimensional signal propagation space, but also an additional smart optical functioning component like as a diffraction-limited imaging lens. The novel and smart functioning of the GRIN substrate was confirmed by experiment on imaging of an input signal to multiple destinations.
The effect of melt instability on the liquid phase epitaxy
Korean Journal of Optics and Photonics, volume 8, issue 5, 1997, Pages 438~442
In this study we report the effect of melt instability on the Liquid Phase Epitaxy. We made a new graphite boat of the structure relieving the instability of melt. It did not improve the uniformity of each layers but also reduced the thickness of growth layers and the deviation of the thickness over 1/2, 1/3 respectively. Moreover, we could get the growth layer of about 80
. With the point of melt stability in view we investigated the effect of InP seed used in two phase solution method. It is concluded that the quality of layers grown by the single crystal is superior to that by the poly crystal in two phase solution method.