• Journal of the Optical Society of Korea
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• 제16권4호
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• pp.401-408
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• 2012

The amplitude error of phase modulator used in closed-loop fiber optic gyroscope has occurred by the temperature dependency of the electro-optic coefficient, and also can be due to the square-wave dither signal which is generally applied for eliminating the deadzone. This error can cause bias drift and scale factor error. This paper analyzes the temperature dependency of the modulation amplitude and the relationship with the scale factor of the gyroscope, and deals with an amplitude control method. The error calculation logic considering the dither signal is implemented on the signal processing module. The result of experiments from a prototype gyroscope shows the effect of the modulation amplitude control and a considerable improvement on performances.

• 한국항공우주학회지
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• 제34권9호
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• pp.97-103
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• 2006

본 논문에서는 디지털 폐루프 신호처리를 이용한 광섬유자이로를 설계하고 성능 시험한 결과를 제시하였다. 회전 입력에 대한 자이로의 피드백 제어를 위해 디지털 세로다인 변조기법이 적용되었고, 환산계수의 안정화를 위해 변조진폭 및 광전력 제어회로를 설계하였다. 프로토타입 광섬유자이로를 시험한 결과, 바이어스 안정도 0.34 deg/hr, 환산계수 비선형도약 100ppm , 회전감지 영역 ${\pm}500$ deg/sec의 성능을 얻었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.528-532
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• 1987

Closed-loop fiber-optic gyroscope with linear scale factor for a wide dynamic range is demonstrated using a gating process and two-harmonic phase modulation, of which the second harmonic is obtained by a frequency doubler. Also the effects of the second harmonic and duty cycle of gating signal on the linearity of scale factor are estimated theoretically and compared with the measured data. The experimental results show the best linearity of scale factor is about 0.5% within the rotation rate 90.deg./sec. The closed-loop fiber-optic gyroscope with gated two-harmonic phase modulation can be used in the application demanding less sensitive performance and modest scale factor linearity.

• 한국항공우주학회지
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• 제37권6호
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• pp.551-555
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• 2009

본 논문은 광섬유 간섭계의 제한된 회전 측정범위($\pi$/2[radian]) 확장을 통하여 고속 회전입력을 감지할 수 있는 광섬유자이로 설계에 관한 연구 결과를 기술하였다. 디지털 세로다인 변조 기법을 바탕으로 광섬유자이로 신호처리 회로를 설계하였으며, 제작된 프로토타입 광섬유자이로의 시험결과 약 ${\pm}3000[deg/sec]$의 고속 회전측정 성능과 약 150[ppm]의 환산계수 성능을 확인하였다. 따라서 본 논문에서는 고속회전 감지를 위한 광섬유자이로 설계의 유효성이 검증되었다.

• Journal of information and communication convergence engineering
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• 제1권1호
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• pp.35-38
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• 2003

Analyses of performance of wireless broadband communication systems employing fiber-optic link have presented. We have analyzed CNR penalty to evaluate system performance by taking into account, radio link considering rainfall attenuation, and optical link considering several carrier-to-noise ratio versus the optical modulation index.

• Current Optics and Photonics
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• 제6권3호
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• pp.323-331
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• 2022

Electro-optic modulator (EOM) takes a vital role in connecting the electric and optical fields. Here, we present a heterogeneously integrated EOM based on the lithium niobate-on-insulator (LNOI) platform. The key modulation waveguide structure is a field-enhanced slot waveguide formed by embedding silicon nanowires in a thin-film lithium niobate (LN), which is different from the previously reported LN ridge or etchless LN waveguides. Based on such slot structure, optical mode field area is reduced and enhanced electric field in the slot region can interact well with LN material with high Electro-optic (EO) coefficient. Therefore, the improvements in both aspects have positive effects on enhancing the modulation performance. From results, the corresponding EOM by adding such modulation waveguide structure achieves better performance, where the key half-wave-voltage-length product (V_𝜋L) and 3 dB EO bandwidth are 1.78 V·cm and 40 GHz under the electrode gap width of only 6 ㎛, respectively. Moreover, Lower V_𝜋L can also be achieved. With these characteristics, such field-enhanced waveguide structure could further promote the development of LNOI-based EOM.

• 한국광학회지
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• 제14권2호
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• pp.155-160
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• 2003

일반 통신용 단일모드 광섬유를 회전 감지용 광섬유로 사용하는 비편광 광섬유 자이로스코프를 제작하고 특성을 측정하였다. 이 자이로스코프의 잡음특성을 계산하여 예측하고, 신호대 잡음비가 최대가 되는 적정 변조진폭 둥의 최적 동작조건을 추출하였다. 자이로의 불규칙잡음계수를 여러 위상차 변조진폭에 대하여 측정한 결과, 위상차 변조진폭이 2.4 rad인 경우에 0.7$\times$$10^{-3}$ deg/√hr의 작은 불규칙잡음계수를 얻을 수 있었으며, 변조진폭에 따른 잡음특성의 경향이 계산에 의한 예측치와 거의 일치하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.839-842
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• 2004

We present a fast-switching electro-optical device based on flexoelectro-optic effect in short pitch cholesterics oriented in uniform lying helix texture. The device has two operating modes: amplitude and phase modulation mode. The amplitude modulation mode is a fast in-plane switching of the device optic axis that enables to achieve a high percent of modulation of the transmitted light intensity whereas the phase mode gives a continuous change of the refractive index and thus of the phase shift of the transmitted light. By using a small concentration of diacrylate monomer and selecting the illumination conditions we have been able to create a inhomogeneous polymeric network mostly localized at both substrate surfaces and stabilize the two switching modes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.508-510
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• 1995

A fiber-optic pressure sensor is fabricated with a photoelastic glass material. To remove the influence of external pertubation along the optical fiber, a new referencing technique is proposed by using two light sources. LED with 870nm wavelength is used as light source for reference signal, and LED with 660nm wavelength is used as light source for modulation signal. The fiber-optic pressure sensor system shows good linearity within the pressure range of 0 to 5 $kg/cm^2$.

• 한국광학회지
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• 제8권5호
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• pp.410-414
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• 1997

Laser projection display(LPD)는 레이저를 이용한 full color의 대형화면을 구현하는 system이다. $TeO_2$와 $LiNbO_3$ 단결정을 음향광학 매질과 transducer로 사용하여 이 system에 쓰이는 영상 신호 처리용 음향광학변조기(Acousto Optic Modulator : AOM)를 제작하고 그 특성을 평가하였다. AOM은 transducer에서 발생된 초음파가 가장 효과적으로 음향광학 매질에 전달되도록 simulation한 후 제작하였으며 제작된 AOM은 특성평가와 더불어 설계값에 맞게 제작되었는가를 회절효율 측정을 통해 검증하였다. LPD System에 실장된 AOM의 회절효율은 85%이며 rise time은 41.5 ns이다.