• Journal of Electrical Engineering and information Science
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• 제3권1호
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• pp.80-85
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• 1998

A theoretical calculation and an optical measurement method of normal-incidence absorption are proposed. By using a waveguide structure, optical interference and the problem of low level signal can be avoided in the measurement of normal-incidence absorption. The oscillator strength of intersubband absorption for a waveguide structure is calculated in Si(001), Si(110), and Ge(001) quantum wells. The polarization angle dependence of the measured and the calculated absorption strength can be obtained with the same waveguide structure, and be compared after normalization. The normal-incidence absorption in Si(110) and Ge(001) quantum wells is shown theoretically, and can be observed in the optical measurement using waveguide structures at the polarization angle of 90$^{\circ}$.

• Tribology and Lubricants
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• 제27권3호
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• pp.156-161
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• 2011

The rectangular waveguide technique can be used to measure the complex permittivity of dielectric material of various thickness and cross section. This paper presents the analysis system of engine oil permittivity at which deterioration of engine oil is measured at the X-band(8-12.5 GHz). The middle of the rectangular waveguide has engine oil case and is connected with VNA(Vector Network Analyzer) for the measurement of the transmission$(S_{21})$ and reflection$(S_11)$ and then the permittivity is extracted. The deterioration of engine oil is proved by the comparison with both the extracted data and reference data. As the additional research, This paper suggest that an accurate permittivity is considered by not only the wave guide length but the air gap between oil case and the waveguide.

• 한국광학회지
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• 제15권6호
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• pp.539-546
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• 2004

고밀도 AWG (Arrayed-Waveguide Grating)의 광 경로차 에러를 정확히 측정하기 위하여 개선된 형태의 저간섭 광원 간섭계를 구성하였고, 새로운 해석방법을 제시하였다. 소프트웨어적인 방법을 이용하여 하드웨어면에서 실험장치를 간략화할 수 있었다. 또한 인접 간섭신호들 사이의 실제 피크 위치 차이를 보간법을 이용하여 정확히 측정할 수 있다. 특정 AWG의 위상 에러를 측정하였고, 이 에러를 가정하여 계산한 파장 투과 특성이 실제 AWG의 파장투과 특성과 유사함을 보임으로써, 제시한 측정 장치의 정확성을 입증하였다.

• Current Optics and Photonics
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• 제4권6호
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• pp.551-557
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• 2020

A mirror-in-slab waveguide is fabricated on a slab waveguide by using the refractive-index contrast between two materials, with the reflection performance depending on the slab waveguide's design. In this research, a slab waveguide design consisting of silicon (Si) as the core and SiO2 as the substrate was designed and developed to determine the coupling, waveguide, and mirror losses. Based on experimental results, coupling loss is dominant and is affected by the design of the slab waveguide. Furthermore, the mirror loss is affected by the design of the mirror, such as the curvature radius and the size of the mirror. TE and TM polarizations of light are used in the measurements. The experimental results show that mirror losses due to reflection by mirrors are 0.011 dB/mirror and 0.007 dB/mirror for TE and TM polarizations respectively. A simulation was performed to confirm whether the size of mirror is sufficient to reflect the input light, and to check the quality of the surfaces of fabricated mirrors.

• 한국인터넷방송통신학회논문지
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• 제12권2호
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• pp.199-203
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• 2012

평행판 도파관에 진행하는 TEM mode를 이용한 평판형 유전체의 유전율을 측정하는 방식을 소개한다. 이는 양 옆이 열린 구조적 장점으로 실험 절차 및 측정 샘플의 가공이 매우 간편한 장점이 있다. 샘플의 유무에 따라 변화하는 도파관 내에서 전파하는 TEM mode의 위상 속도의 차이를 전자기적으로 해석하였고 이를 이용하여 유전체판의 유전율을 측정하였으며, 샘플에 대한 측정 결과는 기존에 알려진 유전율과 일치하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.73-76
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• 1995

In this study, the slab waveguide was fabricated using potassium-nitride(KNO$_3$) or silver-nitride (AgNO$_3$) molten sources by ion-exchange process. The effective refractive indices of waveguide were measured by Prism-Coupling method. and The characteristics of waveguide(mode dispersion, effective diffusion depth. surface refractive index, diffusion coefficient, and refractive index profile etc,) were investigated by WKB method, In the case of potassium ion-exchange, the computer calculation showed that the refractive index profile of waveguide followed Gaussian function, the surface refractive index increased with ion-exchange time and the effective diffusion depth increased a little as ion-exchange time increased, while the surface refractive index of silver ion-exchanged waveguide decreased with ion-exchange time because of the ion depletion on the surface of waveguide, and the effective diffusion depth seriously with ion-exchange tim. Double ion-exchanged waveguide was fabricated by performing silver ion-exchange after potassium ion-exchange. Double ion-exchanged waveguide had a tight mode binding force since the surface refractive index was larger than single step ion-exchanged waveguide.

• 한국세라믹학회지
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• 제42권7호
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• pp.449-454
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• 2005

A waveguide method is developed to study the materials with relatively large dielectric constants at microwave range. Basically, the method is similar to the previous waveguide methods represented by short-circuit line and transmission/reflection measurement methods. However, the complex permittivity is not determined by the shift in resonance frequencies, but by numerical analysis of measured scattering parameters. In order to enhance microwave penetration into the specimen with relatively large permittivity, a dielectric plate with lower permittivity is employed for impedance matching. The influences of air gap between the specimen and waveguide wall are evaluated, and the corresponding errors are estimated. The propagation of higher order modes is also considered. Experimental results for several reference ceramics are presented.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.406-412
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• 2018

In this paper, we propose a narrow resonant waveguide probe that can improve the measurement sensitivity in near-field scanning microwave microscopy. The probe consists of a metal waveguide incorporating the following two sections: a straight section at the tip of the probe whose cross-section is a double-ridged rectangle, and whose height is much smaller than the waveguide width; and a standard waveguide section. The advantage of the narrow waveguide is the same as that of the quarter-wave transformer section i.e., it achieves impedance-matching between the sample under test (SUT) and the standard waveguide. The design procedure used for the probe is presented in detail and the performance of the designed resonant probe is evaluated theoretically by using an equivalent circuit. The calculated results are compared with those obtained using the finite element method (Ansoft HFSS), and consistency between the results is demonstrated. Furthermore, the performance of the fabricated resonant probe is evaluated experimentally. At X-band frequencies, we have measured the one-dimensional scanning reflection coefficient of the SUT using the probe. The sensitivity of the proposed resonant probe is improved by more than two times as compared to a conventional waveguide cavity type probe.

• Journal of electromagnetic engineering and science
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• 제3권1호
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• pp.67-71
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• 2003

In this paper, frequency modulated(FM) reflectometry is proposed to measure group velocity of microwave transmission line Various microwave transmission lines such as periodically loaded conducting posts in a waveguide and nonradiative dielectric(NRD) guide are adopted to measure their group velocity The result compared with that from network analyzer shows good agreement, indicating the validity of our measurement method.

• 센서학회지
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• 제10권1호
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• pp.71-79
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• 2001

The use of a glass-plate probe of rectangular shape is proposed for the measurement of transmission loss in optical waveguides. The light-collecting window is of a thin, rectangular shape and is perpendicular to the light streak, while the conventional fiberglass probe has a small circular face. This transversely elongated form results in a grate improvement of mechanical tolerance for the probe movement in the vortical as well as in the transverse direction. A theoretical investigation also presents a reasonable agreement with the experiments.