• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.260-261
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• 2001

No Abstract.See Full-text

• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.262-263
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• 2001

• Korean Journal of Optics and Photonics
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• v.17 no.2
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• pp.181-185
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• 2006

A novel 60GHz optical carrier generator with a polarization domain-inverted structure is suggested and is demonstrated. The two arms of the Mach-Zehnder optical waveguide are periodically poled for quasi-phase velocity matching between the optical wave at 1550nm and the RF wave at 30 GHz. The center frequency of band-pass modulation and the 3 dB bandwidth of the fabricated modulator were measured to be 30.3 GHz and 5.1 GHz, respectively. Sub-carriers with the frequency difference of 60GHz waeregenerated under appropriate DC biac voltage application while the carrier was suppressed to lead to the power ratio between the modulated sub-carrier and the suppressed fundamental carrier of 28 dB, which proves that double sideband- suppressed carrier(DSB-SC) operation can be realized by the suggested single device.

• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.420-423
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• 2010

We fabricated 1 mm-thick periodically-poled lithium niobate (PPLN) crystals by using a high-voltage amplifier for standard electric field poling combined with a voltage multiplier. Furthermore, two 1 mm-thick PPLNs were directly bonded to make a 2 mm-thick PPLN. The large aperture allowed broad angular tuning, and a broad spectral range of quasi-phase matched second-harmonic generation can be achieved in a single channel. High-power applications are also expected.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.68-69
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• 2003

Quasi-Phase-Matching(QPM)을 이용한 Optical Parametric Oscillation(OPO)은 높은 효율과 작은 Walk-off 효과를 보인다는 장점을 가지고 있다. 그러나 작은 펌프빛의 크기로 인한 빛세기의 증가는 optical damage와 photorefractive effect 야기하고, 이러한 요인으로 안정적인 고출력 연속발진에 있어서는 그 한계가 있으리라고 생각되어진다. 본 연구에서는 주기가 27.7 $mu extrm{m}$인 Periodically poled LiNbO$_3$(PPLN)을 비선형매질로 이용하여 10 kHz의 고반복률을 갖는 다이오드 펌프 Nd：YAG 레이저에서의 Quasi-Phase-Matched Optical Parametric Oscillation의 Signal파의 출력특성 및 안정화에 대하여 조사를 하였다. (중략)

• Current Optics and Photonics
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• v.2 no.6
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• pp.606-611
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• 2018

Measurement of the nonlinear optical coefficients is not an easy task since it requires complicated experimental setup and analysis. We suggest an easy way to estimate the relative nonlinear optical tensor components by direct measurement of the output powers of the second harmonic generation and spontaneous parametric down conversion experiments. The experiments were done in quasi-phase-matched type-0 as well as type-1 interactions at similar pump wavelengths in a 5% MgO-doped periodically poled $LiNbO_3$ crystal to obtain the ratio of the nonlinear optical tensor components $d_{33}/d_{31}$ in each experiment. The obtained ratios were then compared with the previously ascertained values [J. Opt. Soc. Am. B, 14, 2268-2294 (1997)].

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.224-225
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• 2003

Since group velocity (GV) mismatch significantly limits the efficiency of nonlinear interactions such as second harmonic generation (SHG), several techniques have been developed to compensate GV mismatch. The simplest way to avoid the GV mismatch problem is to reduce the device length. However, it results in a poor trade-off between the SHG spectral bandwidth and the conversion efficiency. (omitted)

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.2
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• pp.134-140
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• 2009

In this paper, we discussed the trapezoidal antenna model in the microstrip structure for UWB communications in the frequency band of $3.1{\times}10.6GHz$. Through the computer simulations for the difference size of trapezoidal monopole microstrip antenna model, the good impedance matching characteristic of return loss less than -10dB(VSWR<2) in all the band of UWB showed. The optimized antenna of this paper also showed the quasi-isotropic radiation characteristics in the horizontal plane and linear phase characteristic of nondispersive property.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.762-765
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• 2014

We fabricated a periodically poled lithium niobate (PPLN) by direct laser-writing of a quasi-phase-matching (QPM) structure in photolithographic process. Because we do not need to prepare a photomask by electron-beam writing, the "maskless" process shortens the fabrication time and significantly reduces the cost. We evaluated the poling quality of the direct laser-written PPLN by measuring the diffraction noise from the surface relief pattern of the fabricated QPM grating and comparing the results to those from a conventional PPLN made with a photomask. The quality of the PPLN fabricated by direct laser-writing was shown to be equivalent to that fabricated by the conventional method.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1335-1336
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• 2008

A compact diode-pumped microchip(DPM) green light source which consist of pump LD, $Nd:YVO_4$, KTP and a built-in thermoelectric element has been fabricated for laser projection display. The volume of the source is as small as $0.7\;cm^3$ and we obtained the output power of 25mW with the average electric power consumption in pump LD of 304mW which correspond to the electrical-to-optical efficiency of 7.8%. Another approach using quasi phase matching(QPM) technique has been attempted. We obtained the output power of 90mW of green beam with 350mW pumping of a $Nd:YVO_4$ laser with 20-kHz rep. rate and 10-ns pulse duration. Detailed characteristics and issues of the DPM and QPM green light sources will be addressed.