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>

Tunable Grating Couplers for Broadband Operation Using Thermo-Optic Effect in Silicon

Jong-Hun Kim,Ji-Hwan Park,Sun-Kyu Han,Min-Jung Bae,Dong-Eun Yoo,Dong-Wook Lee,Hyo-Hoon Park IEEE 2015 IEEE Photonics Technology Letters Vol.27 No.21

<P>We demonstrate a tunable grating coupler for broadband operation using an impurity-doped thermo-optic heater fabricated by complementary metal-oxide-semiconductor-compatible processes. As a thermo-optic heater, a p-n diode is employed to have a p-type region inside of an in-coupling grating connected with outside p+/n+ contacts and is heated directly by a current flow through the grating. Applying a forward-bias voltage of 7 V, we shift the central wavelength of the grating coupler from 1525 to 1574 nm with a coupling efficiency of close to -4 dB. Considering a 1-dB bandwidth at each central wavelength, we extend the operational bandwidth to nearly 90 nm. A thermal tuning efficiency of 0.23 nm/mW and transient responses of 32/22 μs for heating/cooling times are obtained.</P>

Spectral-shape-controllable Chirped Fiber Bragg Grating with a Photomechanical Microactuator: Simulation and Experiment

Jong-Ju Moon,고영민,Su-Jeong Park,안태정 한국광학회 2020 Current Optics and Photonics Vol.4 No.6

Recently, one of the authors has been reported an optically tunable fiber Bragg grating (FBG) with a photomechanical polymer. It was based on a typical FBG with a downsized diameter of 60 µm, coated with azobenzene-containing polymer material. Azobenzene is a well-known reversibly photomechanical stretchable material under ultraviolet (UV) light. The small part of the functional-coating region on the FBG absorbed UV light, which pulled the UV-exposed part of the grating. It was selectable as tunable FBG or tunable chirped FBG, by adjusting the position of UV exposure on the grating. As proof of concept for the tunable FBG device, the characteristics just including UV-induced center-wavelength shift and spectral-width changes of the device were reported. In this paper, we report for the first time that the microactuator makes it possible to control the spectral shape of the FBG reflection, according to the specifications (shape and intensity) of the UV beam that reaches the FBG coated with the azobenzene polymer. In addition, we provide the group-delay profiles for the chirped FBG, so that the sign of its dispersion (normal or anomalous) can be tailored by simply selecting the moving direction of the UV light’s displacement in the experiment.

플라즈모닉 격자구조를 이용한 편광감응형 가변 흡수체

이다솔(Dasol Lee),노준석(Junsuk Rho) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12

A broadband tunable absorber is designed and fabricated. The tunable absorber is comprised of a dielectric-metaldielectric multilayer and plasmonic grating. A large size of tunable absorber device is fabricated by nano-imprinting method. The experimental results show that over 90% absorption can be achieved within visible and near-infrared regimes. Moreover, the high absorption can be controlled by changing the polarization of incident light. This polarization-sensitive tunable absorber has practical applications such as high-efficiency polarization detectors and transmissive polarizer.

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.

파장가변 레이저와 회절 기반 간섭계를 이용한 정밀 변위 측정

김종원,고광훈,김병기 한국비파괴검사학회 2019 한국비파괴검사학회지 Vol.39 No.6

we report the analytical and experimental results of precise displacement measurements with a diffraction- based interferometer that uses diffraction gratings. A discrete-wavelength tunable laser with four different wavelengths is used as the light source. The displacement of a target is calculated by counting the maximum and minimum peaks of the interference signal that has a half-wavelength period at each tuned wavelength. The greatest of the four displacement values is then recorded to minimize the measurement error. Such a use of four wavelengths offers significantly smaller error compared to interferometric displacement measurements using a single light source. 본 논문에서는 회결격자를 이용한 회절 기반의 간섭계에 네개의 파장을 가지는 파장가변 레이저를 광원으로 하여 반복 운동을 하는 대상의 정밀 변위 측정에 대한 분석과 실험 결과를 발표한다. 광원의 파장이 변함에 따라 생기는 반파장 주기의 간섭 신호의 최대, 최소 피크의 개수를 세어 측정된 반복 운동 변위를 환산한 후 이들 중 가장 큰 값을 취하면 최소의 오차로 실제 이동한 변위를 측정할 수 있다. 이러한 방법을 통해 단파장을 광원으로 사용한 방법이 가지는 오차를 개선한다.

Tuning Characteristics Analysis of a Widely Tunable Sampled Grating Distributed Feedback Laser Diode Integrated with a Sampled Grating Distributed Bragg Reflector

Suhyun Kim,정영철,변영태 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.4

In this paper, we analyzed the tuning characteristics of a widely tunable sampled grating distributed feedback (SGDFB) laser diode integrated with sampled grating distributed Bragg reflector (SGDBR). The improved time-domain model is used to analyze the laser diode. From the numerical analysis, the length of the phase control region in the SGDFB section has an influence on the output power and the tuning range. Also, the tuning range is observed to be affected by the length of the laser diode, the residual reflectivity at the facet and the position of the facet.

추출격자 분포 브래그 반사기가 집적된 광대역 파장가변 추출격자 분포 궤환 레이저 다이오드의 파장가변 특성해석

김수현,정영철,Kim, Suhyun,Chung, Youngchul 대한전자공학회 2005 電子工學會論文誌-SD (Semiconductor and devices) Vol.42 No.10

본 논문에서는 추출격자 분포 브래그 반사기 (SGDBR: Sampled Grating Distributed Bragg Reflector) 가 집적된 추출격자 분포 궤환 (SGDFB : Sampled Grating Distributed Feedback) 레이저 다이오드의 파장가변 특성을 시뮬레이션을 통하여 분석하였다. SGDFB 영역에 있는 위상제어 영역의 길이는 출력 광 파워와 파장가변 범위에 많은 영향을 미치고 있음을 확인할 수 있었다. 또한 소자의 길이와 단면에서의 반사계수 및 단면의 위치에 의해 전체적인 파장가변 범위가 많은 영향을 받음을 확인하였다. In this paper, we analyzed tuning characteristics of the widely tunable SGDFB laser diode integrated with SGDBR. The improved time-domain model is used to analyse the laser diode. From the numerical analysis, the length of phase control region in the SGDFB section influences on the output power and the tuning range. Also, it was confirmed that the tuning range is affected by the length of the laser diode, the residual reflectivity at the facet, and the position of the facet.

추출격자 분포 브래그 반사기가 집적된 광대역 파장가변 추출격자 분포 궤환 레이저 다이오드

김수현,정영철 한국광학회 2004 한국광학회지 Vol.15 No.4

본 논문에서는 새로운 구조의 파장가변 레이저 다이오드를 제안하였다. 제안된 레이저 다이오드는 추출격자 분포궤환 레이저 다이오드와 추출격자 분포 브래그 반사기가 집적된 구조로 되어 있다. 제안된 레이저 다이오드는 특정한 구조에서 27 nm정도의 광대역 파장가변이 가능함을 수치해석을 통해 확인하였다. 또한 이득영역에서 생성된 광파를 다른 수동영역을 거치지 않고 직접 광섬유에 결합시킬 수 있는 구조로 광효율이 기존의 레이저 다이오드에 비해 우수함을 확인하였다. In this paper, we propose a new tunable laser diode structure. The laser diode consists of a sampled-grating distributed feedback laser diode monolithically integrated with a sampled-grating distributed-Brags-Reflector. For a specific design, the possibility of continuous/discrete wavelength tuning over 27nm is confirmed by a numerical analysis using a split-step time domain model. Because the laser diode can be directly coupled with optical fiber without the intervention of the passive section, the laser diode exhibits higher output power than the conventional laser diode.

나노 임프린트 기술을 이용한 폴리머 도파로 기반의 브래그 격자형 파장 가변 필터

김도환,진원준,이상신,안세원,이기동,Kim, Do-Hwan,Chin, Won-Jun,Lee, Sang-Shin,Ahn, Seh-Won,Lee, Ki-Dong 한국광학회 2006 한국광학회지 Vol.17 No.1

A tunable wavelength filter was proposed and demonstrated by using the UV nanoimprint technique. It consists of a Bragg grating in polymer waveguides and a heating electrode. The manufacturing of the grating was substantially simplified with the introduction of a smart imprint stamp containing a waveguide pattern integrated with the grating pattern. The center wavelength of the filter was successfully tuned by taking advantage of the thermooptic effect in polymers, which was induced by supplying electrical power to the electrode. For the fabricated device, a transmission dip of ${\~}$15 dB and a 3-dB bandwidth of 0.8 nm were obtained at the Bragg wavelength of ${\~}$l560 nm. The achieved thermooptic tuning efficiency was ${\~}$0.28 nm/mW, while the center wavelength was shifted from 1560 nm to 1558 nm with the electrical power consumption of 7 mW. 본 논문에서는 UV 나노임프린트 기술을 이용하여 파장가변 필터를 제안하고 구현하였다. 제안된 소자는 폴리머 도파로 기반의 브래그 격자와 열 광학효과를 위한 히팅용 전극으로 구성되어 있다. 도파로 패턴과 브래그 격자 패턴이 결합된 임프린트용 스탬프를 이용하여 브래그 격자를 구현하였다. 전극에 전력을 인가하여 폴리머의 열 광학효과를 통하여 필터의 중심파장을 효과적으로 이동시킬 수 있었다. 제작된 소자는 브래그 파장대역인 1560 nm 에서 대역저지 소멸비가 15 dB이며, 대역폭이 0.8 nm였다. 또한 소비전력이 7 mW일 때 중심파장은 1560 nm에서 1558 nm로 이동되었다. 이 때 열 광학효과 파장가변 특성이 약 0.28 nm/mW 였다.