OFDR을 이용한 PZT형 파장가변 필터의 이력 측정

박도현,예윤해,Park, Do-Hyun,Yeh, Yun-Hae 한국광학회 2008 한국광학회지 Vol.19 No.1

PZT형 파장가변 필터를 이용하여 파장스윕(wavelength-swept) 광원을 구성할 때 발진파장의 변화율을 일정하게 하려면 필터의 이력(hysteresis)특성을 알아야 한다. 이력특성을 무시하고 필터를 구동할 경우 파장스윕 광원을 사용하는 optical frequency domain reflectometry(OFDR) 시스템의 분해능이 떨어진다. 광스펙트럼 분석기(OSA)를 이용하여 필터의 이력특성을 측정할 수도 있지만 측정시간이 너무 길고 실제 구동조건에서의 이력특성은 측정할 수 없다는 문제가 있어 실제 구동조건에서 필터의 이력특성을 고속으로 측정할 수 있는 OFDR의 원리에 기초한 이력 측정법을 제시하였다. 파장스윕 광원과 간섭계, 신호처리 장치, 그리고 PC 프로그램으로 구성된 고속 이력측정장치를 구현하고, 이를 사용하여 필터 구동조건에서의 이력특성을 측정하였다. 마지막으로 측정된 이력특성을 파장스윕광원의 구동에 적용하여 선형적 파장변화를 얻음으로써 새로운 이력측정법의 유효성을 검증하였다. Implementation of a wavelength-swept source with constant tuning rate adopting a PZT-type tunable filter, requires the knowledge of hysteresis of the filter used. The hysteresis must be considered to avoid any degradation in resolution of the optical frequency domain reflectometry (OFDR) system. An optical spectrum analyzer (OSA) could be used to do the hysteresis measurement, but its measurement time is too long for the high-speed driving conditions for the filter. We proposed a new hysteresis measurement method based on OFDR, which could measure the hysteresis in a real driving condition. A hysteresis measurement apparatus consisted of wavelength-swept source, interferometer, signal processing unit, and PC program is built and used to do the measurement. It is concluded that the new method is useful in the measurement of hysteresis at real driving conditions by successfully implementing a swept-wavelength source whose wavelength change is linear in time.

A Flexible and Tunable Microwave Photonic Filter Based on Adjustable Optical Frequency Comb Source

Tran, Thanh Tuan,Seo, Dongsun Institute of Korean Electrical and Electronics Eng 2015 전기전자학회논문지 Vol.19 No.1

A flexible and tunable microwave photonic filter based on adjustable optical frequency comb source is demonstrated. We use a combination of a dual parallel Mach Zehnder modulator and an intensity modulator to generate fifteen comb lines with proper weights to implement a desired filter. The optical comb weights, corresponding to the tap coefficients of the filter, are flexibly changed by adjusting the operation parameters of the modulators. The achieved bandwidth and stopband attenuation of the tunable filter are 0.7 GHz and 20 dB, respectively. In addition, we overcome the undesired low frequency suppression appeared in a conventional scheme by applying a dual parallel Mach Zehnder modulator for single sideband suppressed carrier modulation.

A Flexible and Tunable Microwave Photonic Filter Based on Adjustable Optical Frequency Comb Source

Thanh Tuan Tran,서동선 한국전기전자학회 2015 전기전자학회논문지 Vol.19 No.1

A flexible and tunable microwave photonic filter based on adjustable optical frequency comb source is demonstrated. We use a combination of a dual parallel Mach Zehnder modulator and an intensity modulator to generate fifteen comb lines with proper weights to implement a desired filter. The optical comb weights, corresponding to the tap coefficients of the filter, are flexibly changed by adjusting the operation parameters of the modulators. The achieved bandwidth and stopband attenuation of the tunable filter are 0.7 GHz and 20 dB, respectively. In addition, we overcome the undesired low frequency suppression appeared in a conventional scheme by applying a dual parallel Mach Zehnder modulator for single sideband suppressed carrier modulation.

Investigation of smart multifunctional optical sensor platform and its application in optical sensor networks

Pang, C.,Yu, M.,Gupta, A.K.,Bryden, K.M. Techno-Press 2013 Smart Structures and Systems, An International Jou Vol.12 No.1

In this article, a smart multifunctional optical system-on-a-chip (SOC) sensor platform is presented and its application for fiber Bragg grating (FBG) sensor interrogation in optical sensor networks is investigated. The smart SOC sensor platform consists of a superluminescent diode as a broadband source, a tunable microelectromechanical system (MEMS) based Fabry-P$\acute{e}$rot filter, photodetectors, and an integrated microcontroller for data acquisition, processing, and communication. Integrated with a wireless sensor network (WSN) module in a compact package, a smart optical sensor node is developed. The smart multifunctional sensor platform has the capability of interrogating different types of optical fiber sensors, including Fabry-P$\acute{e}$rot sensors and Bragg grating sensors. As a case study, the smart optical sensor platform is demonstrated to interrogate multiplexed FBG strain sensors. A time domain signal processing method is used to obtain the Bragg wavelength shift of two FBG strain sensors through sweeping the MEMS tunable Fabry-P$\acute{e}$rot filter. A tuning range of 46 nm and a tuning speed of 10 Hz are achieved. The smart optical sensor platform will open doors to many applications that require high performance optical WSNs.

Investigation of smart multifunctional optical sensor platform and its application in optical sensor networks

C. Pang,M. Yu,A.K. Gupta,K.M. Bryden 국제구조공학회 2013 Smart Structures and Systems, An International Jou Vol.12 No.1

In this article, a smart multifunctional optical system-on-a-chip (SOC) sensor platform is presented and its application for fiber Bragg grating (FBG) sensor interrogation in optical sensor networks is investigated. The smart SOC sensor platform consists of a superluminescent diode as a broadband source, a tunable microelectromechanical system (MEMS) based Fabry-Pérot filter, photodetectors, and an integrated microcontroller for data acquisition, processing, and communication. Integrated with a wireless sensor network (WSN) module in a compact package, a smart optical sensor node is developed. The smart multifunctional sensor platform has the capability of interrogating different types of optical fiber sensors, including Fabry-Pérot sensors and Bragg grating sensors. As a case study, the smart optical sensor platform is demonstrated to interrogate multiplexed FBG strain sensors. A time domain signal processing method is used to obtain the Bragg wavelength shift of two FBG strain sensors through sweeping the MEMS tunable Fabry-Pérot filter. A tuning range of 46 nm and a tuning speed of 10 Hz are achieved. The smart optical sensor platform will open doors to many applications that require high performance optical WSNs.

SLD 동조 광원을 이용한 브라그 파장 측정 LPG 센서의 신호처리 시스템

이호준,배윤경,Lee Hojoon,Bae Yoonkyung 한국광학회 2004 한국광학회지 Vol.15 No.5

본 논문에서는 광섬유 장주기 격자를 이용한 센서 신호처리 시스템을 구현하였다. SLD와 Fabry-Perot 필터를 이용한 동조 반도체 광원과 Fabry-Perot 필터내의 PZT의 히스테리시스 특성을 보상하기 위한 에탈론 필터를 사용하였으며, 절대적인 기준 파장을 제공하기 위하여 온도 안정화된 광섬유 브래그 격자를 사용하였다. 시스템에서 검출된 신호를 A/D 변환하여 컴퓨터로 입력하고 신호 처리하여 결과를 모니터상에 표시하였다. A signal processing system of long period grating sensor that works in the optical wavelength domain is proposed. The system is based on a wavelength-swept semiconductor light source that includes an SLD and a F-P tunable filter. The hysteresis effects of PZT in the F-P filter is compensated by using an etalon filter and an athermal Fiber Bragg Grating. The detected signals from the photodiode are transmitted to a computer using an A/D converter and the result of the process is displayed in the monitor.

SS-OCT 시스템 적용을 위한 FDML 방식의 고속 파장가변링 레이저 구현

안상호,엄진섭 강원대학교 정보통신연구소 2009 정보통신논문지 Vol.13 No.-

In this paper, we have demonstrated a Fourier Domain Mode-locked wavelength swept laser for SS-OCT system. The proposed FDML ring laser is constructed by long fiber ring cavity, a semiconductor optical amplifier, and a tunable fiber Fabry-Perot filter. Effective sweep rate of up to 123kHz(forward 61.5kHz, backward 61.5kHz) is demonstrated with a 10.53μm axial resolution and a 75nm tuning range at 1340nm center wavelength.

Concurrent hypermulticolor monitoring of CD31, CD34, CD45 and CD146 endothelial progenitor cell markers for acute myocardial infarction

Shim, Yumi,Nam, Myung Hyun,Hyuk, Song Woo,Yoon, Soo Young,Song, Joon Myong Elsevier 2015 Analytica chimica acta Vol.853 No.-

<P><B>Abstract</B></P> <P>The circulating endothelial progenitor cells (EPCs) in blood of acute myocardial infarction (AMI) patient have been monitored in many previous studies. The number of circulating EPC increases in the blood of patients at onset of the AMI. EPC is originated from bone marrow. It performs vessel regeneration. There are many markers used for detecting EPC. Four of these markers, CD31, CD34, CD45, and CD146, were concurrently detected at the single cell level for the identification of EPC in the present preliminary study. The CD45 negative cell sorting was performed to peripheral blood mononuclear cells (PBMCs) acquired from four AMI patients with a magnetic bead sorter, since, EPCs expressed CD45 negative or dim. The resultant PBMC eluents were treated with quantum-antibody conjugates for the probing four different markers of EPCs and then applied to a high-content single cell imaging cytometer using acousto-optical tunable filter (AOTF). The use of quantum dot, with narrow emission wavelength range and AOTF enabling cellular image at a particular single wavelength, is very advantageous for accurate high-content AMI diagnosis based on simultaneous monitoring of many markers. The number of EPC increased as compared with control in three of four AMI patients. In this approach, two EPC subtypes were found, CD31(+), CD34(+), CD45(−/dim), CD146(−) as early outgrowth EPCs and CD31(+), CD34(+), CD45(−/dim), CD146(+) as late outgrowth EPCs. Patient 1 had CD31(+), CD34(+), CD45(−/dim), CD146(+) cells whose percentage was 4.21% of cells. Patient 2 had 2.38% of CD31(+), CD34(+), CD45(−/dim), CD146(−) cells and patient 3 had 4.28% of CD31(+), CD34(+), CD45(−/dim), CD146(+) cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We observe EPCs and HPCs in patient for AMI diagnosis. </LI> <LI> We detect two EPC subtypes using quantum dot and AOTF. </LI> <LI> Quantum dot has narrower emission wavelength range than fluorescence dye. </LI> <LI> AOTF provide smaller spectral interference than bandpass filters. </LI> <LI> Quantum dot and AOTF are suitable for detecting large number of molecular markers concurrently. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

온도 컨트롤러를 이용한 FBG 파장 가변 광 필터에 관한 연구

정진호(Jin-Ho Jung) 호서대학교 공업기술연구소 2006 공업기술연구 논문집 Vol.25 No.1

An optical filter is an important element in an optical WDM system. Because the number of the optical filters have to be same as the number of the transmission wavelengths in a WDM system, many optical filters are required. To decrease the number of the optical filters, the optical wavelength tunable filters need. In this paper, therefore, an optical wavelength tunable FBG filter which its center wavelength is shifted by temperature is proposed. To realize this optical tunable filter, reflectance and transmittance as a function of temperature are found, and its output(transmission) spectrum is measured by the optical spectrum analyzer. The measured results show that the center frequency is shifted approximately 0.0108 [nm/°C ].

A tunable photonic microwave notch filter using a multiple wavelength optical source

Choi, Yong-Kyu,Jeon, Sie-Wook,Kim, Youngbok,Keun Oh, Choong,Park, Chang-Soo Wiley Subscription Services, Inc., A Wiley Company 2010 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.52 No.1

<P>We propose a tunable photonic microwave notch filter using a multi-wavelength optical source. Two peak wavelengths are generated using a reflective semiconductor optical amplifier (RSOA) self-injection, locked by two external fiber Bragg gratings (FBGs). The time delay required for the notch filter is obtained based on the wavelength-dependent propagation velocity through the fiber. The tunable filter characteristic is obtained by changing the center wavelength of one of the gratings and its tunability is limited only by the gain profile of the RSOA and the tuning range of the grating. Based on the proposed structure, a two-tap microwave notch filter with free spectral range tunable from 1.15 to 5.79 GHz is experimentally demonstrated. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 134–138, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24841</P>