• Korean Journal of Optics and Photonics
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• 제12권4호
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• pp.327-333
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• 2001

Estimation of the frequency response of Ti:LiNb03 traveling-wave optical modulator with phase reversal electrodes is succinctly presented. The fact that such devices may have bandpass characteristics is demonstrated through simulations based on the derived equations. The influence of each parameter of traveling-wave electrodes on the frequency response is investigated in detail. It is shown that the center frequency and the bandwidth of response curves can be effectively adjustable by changing the MW effective index and the interaction length of the electrodes. rodes.

• Korean Journal of Optics and Photonics
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• 제14권2호
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• pp.161-165
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• 2003

Optical 60 ㎓ millimeter-wave (MMW) signal generation is demonstrated using the sideband injection-locking method in the master/slave configuration, where two slave lasers are locked to two among several side-bands produced by the direct rf-modulation of a master laser. These two locked slave laser outputs beat against each other in the photo-detector and produce stable and very pure 60 ㎓ signals.

• Current Optics and Photonics
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• 제6권4호
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• pp.400-406
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• 2022

We numerically demonstrate that the inherent spiking behavior in the quasi-continuous-wave (QCW) operation of an Nd:YAG laser can be suppressed by adopting bias pumping. After spiking suppression, the output QCW pulses from a bias-pumped Nd:YAG laser are very stable, and they can maintain nearly the same temporal shape as that of pump pulse under different pump repetition rates and peak powers. Our study implies that bias pumping is an alternative method of spiking suppression in solid-state lasers, and the application areas of an Nd:YAG laser may be extended by bias pumping.

• Korean Journal of Optics and Photonics
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• 제18권1호
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• pp.66-73
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• 2007

The various output characteristics of a pulsed Ti:sapphire laser oscillator with a plane-parallel resonator, pumped longitudinally by the second harmonic wave of a Nd:YAG laser, and the output of a Ti:sapphire laser amplifier operated along the single path of the oscillator beam were investigated and analyzed. In the case of the oscillator, we measured the spectrum, the pulse buildup time, the temporal duration time of the pulse, and the output energy according to the variation of the pumping energy, resonator length, and the reflectance of the output coupler. And, in the case of the amplifier, we investigated and analyzed the output energy of the amplifier as a function of the time difference between the two pump beams of the oscillator and the amplifier, the pumping energy of the oscillator, and the pumping energy of the amplifier When pump energies of both the oscillator and the amplifier were 18 mJ/pulse, we could find that the output energy of the amplifier increased linearly and gradually up to the time difference of 35 ns. Finally, we determined that the slope efficiencies of the oscillator and the amplifier were 23.5 % and 11.6 %, respectively.

• Korean Journal of Optics and Photonics
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• 제14권4호
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• pp.434-442
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• 2003

Taking advantage of the probability function, we have analyzed the localization phenomenon of the solution of a propagating function under the condition that the propagation constants are randomly distributed. For example, we have investigated the localization phenomenon of the voltage wave for a transmission line in which the characteristic impedance is randomly distributed. We have confirmed that the localized solution is in existence on the random lossless transmission line. Even in the case that the voltage wave is impulsively excited by the current source, the voltage wave is localized. Because the light wave is seriously affected at the localized position in the lossy transmission line, we have determined that the light wave localization phenomena are generated by multi-reflection.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제27권5호
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• pp.471-481
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• 2016

We introduce the design technique and test results of a millimeter-wave compact antenna test range. Physical optics is employed for the analysis of the plane wave collimated by an electrical large parabolic reflector of the compact range in the test zone. The performance of the manufactured compact range is verified with the field probing test on the quiet zone and the measurement of high gain antenna. A millimeter-wave compact range designed in the frequency range of 75~110 GHz with a diameter of the test zone of 50 cm shows the magnitude variation of less than 0.75 dB.

• Korean Journal of Optics and Photonics
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• 제5권1호
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• pp.37-44
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• 1994

The characteristics of stimulated Brillouin scattering wave for applications to high power laser was experimentally investigated. The peak power reflectivity and the phase conjugation fidelity of Stokes wave with respect to the focal length of lens were measured, and the phase conjugation fidelity for a compressed part of the Stokes wave was also investigated. For the long focal length of lens.(f=100 cm), the peak power of the Stokes wave amounts to about twice as high as that of incident wave. The phase conjugation fidelity for the compressed leading pulse is up to 90%, better than that for other temporal parts of the Stokes pulse. In spatial distribution, the Stokes pulse from the axial region has the largest SBS gain, and it has been ascertained as a best candidate to the application due to excellent pulse compression, peak power reflectivity, and good phase conjugation fidelity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제8권1호
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• pp.1-12
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• 1997

The acousto-optical spectrometer as a new type backend of the receiver system for radio astronomical observations is manufactured for radio signal analysis. We studied on the effect of Acousto-Optic and Acousto-Optic devices and designed the optics system. We manufactured the optical mount and the CCD detector for deflected beam and interface card. This acousto-optical spectrometer consisted of a laser, optics, acousto-optic deflector, CCD detector and Interface card. This system use He-Ne laser as a light source and use optics to get parallel beam and to focus the deflected beam. Acousto-optic deflector converts IF signal to ultrasonic wave and deflect the laser beam according to the Bragg deflection. The ultra wide band acousto-optic deflector has 1 GHz bandwidth and a total of 2,048 channel Charge Coupled Device for signal detection. In this study, we discuss the theoretical description on the effect of Acousto-optics, the design of the optics, manufacture of optical mount, CCD detector, interface card and we presented the results of experiment. As a result of measurement, we have 1,000 channels bandwidth from CCD channels.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제26권5호
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• pp.445-454
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• 2015

In this paper, we propose an optimal design method for a dual reflector antenna(DRA) using the Genetic algorithm. In order to reduce the computational burden during the optimal design, we exploit the iterative physical optics(IPO) to calculate the surface current distribution at each reflector antenna. To improve the accuracy, we consider the shadow effect by the structure and the coupling effect by the multi-reflection based on the iterative MFIE(Magnetic Field Integral Equation). To reduce the number of design variables and generate a smooth surface, we use the Bezier function with the control points, which become the design variables in this paper. We adopt the HPBW(Half Power Beam Width), the FNBW(First Null Beam Width), and the SLL(Side Lobe Level) as the objective or cost functions. To verify the results, we compare them with the those of the commercial tool.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제20권8호
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• pp.791-796
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• 2009

A hybrid iterative physical optics-method of moments(IPO-MoM) technique is presented for the analysis of jet engine structures which are both electrically large and complex. In this technique, the IPO method is used to analyze smooth inlet region and the MoM method is used to analyze electrically complex region inclusive of blades and hub. It is efficient and accurate by virtue of combining the respective merits of both methods. Numerical results are presented and validated through comparison with Mode-FDTD and measured results.