• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.89-95
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• 2008

The Acousto-Optic Tunable Filter (AOTF) is a high-speed full-field monochromator which generates two spectrally filtered light beams with ordinary and extraordinary polarization state. Thus, AOTF is widely used to build full-field spectral imaging system or spectral domain interferometer. However, AOTF has a big problem that the angle of diffracted light changes according to the scanning of wavelength, which makes image shift on CCD plane In this paper, we propose an analytic design of prism system to compensate the image shift. The detailed analysis of light paths in a prism and basic experimental results are presented to verify our proposed compensation method. The experimental results agree with simulation results based on suggested prism model and image shift is minimized at optimal condition. Also, it can be extended to compensate the image shift for ordinary and extraordinary polarized light simultaneously.

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.298-299
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• 2004

We propose and theoretically analyze multi-functional integrated optical device based on figure-eight shaped birefringent Sagnac loops. Our analysis shows that the propose device exhibit many unique features which allows it to operate as a tunable high-Q comb filter with a good channel isolation, and the intensity transmission of the filter can be varied from zero to 100 percent.

• Proceedings of the KIEE Conference
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• 1979.08a
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• pp.34-36
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• 1979

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.282-283
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• 2004

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.1
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• pp.43-48
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• 2009

We constructed a simple wavelength readout system for a tunable fiber laser which was used for a fiber Bragg grating sensor array system. A quadrature sampling method was used to demodulate wavelength variations of the tunable laser which consisted of a SOA(semi-conductor optical amplifier) and a fiber-optic Fabry-Perot filter. Internal triggers, which have a 90 degree phase period, have been generated by using a double-pass Mach-Zehnder interferometer. From Lissajous plots with quadrature sampled data, a mean phase error of ${\sim}2.51$ mrad was obtained. From the wavelength readout experiments, an accurate and fast linear wavelength demodulation has been confirmed.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.161-164
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• 2002

In this paper, a design technique is introduced for designing a 360-degree linear analog phase shifter at 1.8㎓. Using tunable short-circuit terminated comb-line filters as reactive loads, the circuit gives a very small insertion loss(less than 0.1㏈) and an almost linear phase shifter over the filter bandwidth for the full 360-degree range. We were showed large phase variation with small capacitance variation in the quadrature hybrid coupler using tunable shorted terminated combline filters.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.4
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• pp.59-64
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• 2009

In this paper, we represent characteristics and equivalent circuit of donut type resonator of defected ground structure (DGS), and can control resonant frequency with chip capacitor. In General, DGS operates like with parallel LC resonator. We found out variation of resonance frequency when capacitor is placed on slot of DGS. If the chip capacitor replace with varactor diode, the resonance frequencies can be controlled by voltage. This tualable resonator can apply to voltage controlled oscillator and tunable bandpass filter.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1593-1594
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• 2006

본 논문에서는 모바일 컨버젼스 단말기를 위한 Tunable Image Rejection Filter를 구현 하였다. 이 필터는 TSMC 0.25um 공정을 이용해 시뮬레이션 되었다. 또한 정전기로 인한 소자의 파괴를 방지하기 위해 ESD 패드(Electro Static Discharge Pad)를 추가하였다. 영상 주파수 저지 특성은 WCDMA(2.1GHz), WiBro(2.3GHz), WLAN(2.45) 대역에서 모두 28dB 이상이고, 이때 바이어스 전압은 각각 0.5V, 0.95v, 1.8V의 전압을 가지게 되었다. 삽입 손실은 세 대역에서 모두 2dB 이하이다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.11
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• pp.17-22
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• 2005

In this study, we suggested wave-variable Bragg lattice using the characteristic of the Bragg wave that varies according to the change of the temperature imposed on the optical fiber lattice device, and experimented using a simulation test. We analyzed the results of the FBG change according to the change of the temperature obtained in the variable FEG computer simulation and experiment to suggest optimal data. Therefore, utilizing wave-variable optical filter through FBG allows us to combine other channels beyond optical fiber lattice device wave, and can be used as a helpful device in the Dense Wavelength Division Multiplexed system with a channel intervention of 0.08nm(10GHz).

• Journal of the Korean Institute of Telematics and Electronics
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• v.8 no.4
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• pp.25-30
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• 1971

Fabrication and measurements of the magnetically tunable YIG band pass or stop filter at X-band are discussed. Using two YIG spheres located at the region of r-f circularly polarized magnetic field between the strip lines, the pass or stop characteristics of the filter are obtained. In the case of band stop, the output level is typically 25db lower than the input power. Contrarily for the pass band, the pass band level is 22db higher than the stop frequency region. The experimental results are in good agreement with the theoretical values of FMR. Further it is shown that the structure can be used for a directional coupler.