• 센서학회지
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• 제30권6호
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• pp.395-407
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• 2021

The effect of the specifications of a silicon-on-insulator vertical slot optical waveguide on the sensitivity of homogeneous and surface sensing configurations for TE and TM polarization, respectively, was systematically analyzed using numerical software. The specifications were optimized based on the confinement factor and transmission power of the TE-guided mode distributed in the slot. The waveguide sensitivities of homogeneous and surface sensing were calculated according to the specifications of the optimized slot optical waveguide.

• 전기학회논문지
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• 제65권1호
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• pp.108-111
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• 2016

We propose the method for measuring sensitivity of optical receiver of a long-range laser range finder in real-time. The sensitivity of the detector can be calculated using the detected voltage of the reference sensor, the area of the reference sensor and the transmittance ratio of neutral density filters. To evaluate the performance of the proposed method, we implemented a system and performed experiments. As a result, this system can be measured from 2nW to $113{\mu}W$. With this system, we measured the sensitivity of 37nW and 7nW with PIN PD and APD sample, respectively. This system has the advantage for the performance test of an optical sensor module in the long-range laser range finder.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.153-153
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• 2012

Endpoint detection with plasma impedance monitoring and self-plasma optical emission spectroscopy is demonstrated for dielectric layers etching processes. For in-situ detecting endpoint, optical-emission spectroscopy (OES) is used for in-situ endpoint detection for plasma etching. However, the sensitivity of OES is decreased if polymer is deposited on viewport or the proportion of exposed area on the wafer is too small. To overcome these problems, the endpoint was determined by impedance signal variation from I-V monitoring (VI probe) and self-plasma optical emission spectroscopy. In addition, modified principal component analysis was applied to enhance sensitivity for small area etching. As a result, the sensitivity of this method is increased about twice better than that of OES. From plasma impedance monitoring and self-plasma optical emission spectroscopy, properties of plasma and chamber are analyzed, and real-time endpoint detection is achieved.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2272-2278
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• 2011

광통신 시스템에서 신호와 부가적인 잡음의 통계적인 특성에 대해 다양한 방법으로 평가하는 것은 시스템의 성능 최적화를 위해 필수적인데, 본 연구에서는 수신기의 성능 평가 방법으로 다양한 에러 확률을 대역폭과 비트수의 함수(m)로 표현하여 수신기의 성능을 평가를 통하여 광통신시스템에서 사용되고 있는 PIN 수신기의 수신감도를 해석하였고 시뮬레이션을 통해 이를 확인하였다. 그 결과 m=20인 경우, PIN 수신기의 수신 감도는 주어진 에러 확률을 유지하기 위해 대략 $9.2{\times}10^4$ 광자/비트 정도가 필요함을 확인 할 수 있었다.

• Current Optics and Photonics
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• 제7권5호
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• pp.504-510
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• 2023

An optical fiber dislocation fusion humidity sensor coated with graphene quantum dots is investigated. A Mach-Zehnder interferometer is fabricated with three dislocated single-mode fibers with graphene quantum dots coating humidity-sensitive materials. Humidity response experiments showed a good linear response and high sensitivity with easy fabrication and low-cost materials. From 22% to 98% RH, the humidity response sensitivity of the sensor is 0.24 dB/% RH, with 0.9825 linearity. To investigate the cross-response of humidity and temperature, temperature response experiments are conducted. From 30 ℃ to 70 ℃, the results showed 0.02 dB/℃ sensitivity and 0.9824 linearity. The humidity response experimental curve is compared with the temperature experimental curve. The big difference between humidity sensitivity and temperature sensitivity is very helpful to solve the cross-response of humidity and temperature. The influence of temperature fluctuations in humidity measurements is not obvious.

• 센서학회지
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• 제30권5호
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• pp.331-336
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• 2021

The Non-dispersive Infrared (NDIR) gas sensor has high selectivity, measurement reliability, and long lifespan. Thus, even though the NDIR gas sensor is expensive, it is still widely used for carbon dioxide (CO₂) detection. In this study, to reduce the cost of the NDIR CO₂ gas sensor, we proposed the new optical waveguide structure design based on ready-made gas pipes that can improve the sensitivity by increasing the initial light intensity. The new optical waveguide design is a structure in which a part of the optical waveguide filter is inclined to increase the transmittance of the filter, and a parabolic mirror is installed at the rear end of the filter to focus the infrared rays passing through the filter to the detector. In order to examine the output characteristics of the new optical waveguide structure design, optical simulation was performed for two types of IR-source. As a result, the new optical waveguide structure can improve the sensitivity of the NDIR CO₂ gas sensor by making the infrared rays perpendicular to the filter, increasing the filter transmittance.

• 한국광학회지
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• 제32권3호
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• pp.126-132
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• 2021

본 논문에서는 특이 광 투과 현상 센서에서 보조 파장 홀 패턴에 입사되는 광원의 각도 조절을 통해 센서의 민감도를 측정 및 분석하여 이를 극대화할 수 있는 방법을 고안하였다. 입사파 광원을 평행화된 광원과 각도가 서로 다른 두 개의 집속화된 광원 총 3개의 광원을 시스템적으로 설계하여 서로 다른 각도로 보조 파장 홀 패턴에 입사되게 제작하였다. 그리고 증류수(n=1.333)와 굴절률 정합액(n=1.360, 1.380)을 사용하여 투과 스펙트럼을 측정하고 센서의 민감도를 계산한 결과 평행화된 광원을 사용하였을 때 센서의 민감도가 향상됨을 확인하였다.

• Journal of the Optical Society of Korea
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• 제14권1호
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• pp.14-21
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• 2010

Fiber ring laser based intra-cavity absorption spectroscopic sensor has great potential for high sensitivity gas detection. Using the rate equations and propagation equations, we investigated theoretically factors that affect the sensitivity of such fiber ring laser sensors and determined the optimal design parameters and conditions for significant enhancement of the system sensitivity. Experiments have been conducted to determine the sensitivity enhancement performance. The results showed a factor of 25 ~ 30 in sensitivity enhancement in the experimental system, agreeing well with the theoretical expectations. Experiments on acetylene detection have also been carried out and the results showed that the ring cavity significantly increases the signal absorption and that high sensitivity can be obtained for gas detection.

• Journal of the Optical Society of Korea
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• 제20권5호
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• pp.623-627
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• 2016

A power-adjustable fully-integrated CMOS optical receiver with multi-rate clock-and-data recovery circuit is presented in standard 65-nm CMOS technology. With supply voltage scaling, key features of the optical receiver such as bandwidth, power efficiency, and optical sensitivity can be automatically optimized according to the bit rates. The prototype receiver has −23.7 dBm to −15.4 dBm of optical sensitivity for 10⁻⁹ bit error rate with constant conversion gain around all target bit rates from 1.62Gbps to 8.1 Gbps. Power efficiency is less than 9.3 pJ/bit over all operating ranges.

• Current Optics and Photonics
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• 제7권1호
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• pp.21-27
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• 2023

A highly sensitive optical-fiber humidity sensor is demonstrated in this paper. By using Nafion-PVA sol-gel and single-mode optical fibers, the Fabry-Perot humidity sensor is easily fabricated. In the humidity range of 29%-72%, humidity-response experiments are carried out with a cycle of rising and falling humidity to investigate humidity-response characteristics. The experimental results show 2.25 nm/%RH sensitivity and a 0.9997 linear correlation coefficient, with good consistency. The changes in optical-path difference (OPD) and free spectral range (FSR) with humidity are also discussed. The humidity sensitivities of a typical sensor are 80.3 nm/%RH (OPD) and 0.03 nm/%RH (FSR). Furthermore, many humidity sensors with different Nafion-PVA sol-gel concentration and initial cavity length are experimentally investigated for humidity response. The results show that the sensitivity increases with higher Nafion ratio of the Nafion-PVA sol-gel. The influence of changing cavity length on sensitivity is not obvious. These results are helpful to research on optical-fiber humidity sensors with good performance, easy fabrication, and low cost.