• Title/Summary/Keyword: Microwave photonics

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Microwave Photonics Frequency-Converted Link Using Electroabsorption Devices

  • Wu, Y.;Shin, D.S.;Chang, W.S.C.;Yu, P.K.L.
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.4 no.1
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    • pp.74-81
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    • 2004
  • We propose a novel scheme to transmit high center frequency RF signals using electroabsorption devices (EADs) as frequency converters at the transmitter and the receiver. In this approach frequency heterodyning is employed for obtaining high center frequency. With the EAD as a detector/mixer at the receiver we demonstrated a smaller conversion loss than that of the conventional modulator/mixer. With EAD as a modulator/mixer at the transmitter and with two heterodyned lasers to generate an optical local oscillator (LO), we demonstrated a large reduction (${\sim}23dB$) in conversion loss, and the transmission is not limited by the optical saturation of the EAD. This transmission scheme has optical single-side-band transmission feature which greatly relieves the fiber dispersion effect.

Analysis and design of traveling-wave mushroom-type electroabsorption modulator using FDTD method (FDTD를 이용한 진행파형 버섯형 전계흡수 변조기의 분석 및 설계)

  • Ok, Seong-Hae;Gong, Sun-Cheol;Choe, Yeong-Wan;Lee, Seok;U, Deok-Ha;Kim, Seon-Ho
    • Proceedings of the Optical Society of Korea Conference
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    • 2001.02a
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    • pp.156-157
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    • 2001
  • 전계 흡수 광 변조기는 우수한 소광비와 낮은 전력 소모로 넓은 대역폭을 확보할 수 있으며 LD와의 단일 집적인 EML(electro-absorption modulator integrated laser diode)의 제작도 용이하므로 Microwave-Photonics 시스템에 매우 적합한 소자로써 근래에 활발한 연구가 진행되어지고 있다. 전계 흡수 광 변조기의 대역폭을 최대한 확보하기 위해서는 진행하는 마이크로파의 위상속도와 광파의 그룹 속도가 정합 되어야 하며 소자의 임피던스가 50Ω에 정합 되어야 한다. (중략)

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Microwave Photonics Devices (마이크로파 및 밀리미터파 통신용 광소자의 기술 동향)

  • 최영완;윤영설
    • Optical Science and Technology
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    • v.10 no.1
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    • pp.36-43
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    • 2006
  • 지난 2005년 10월 서울 올림픽파크텔에서 개최된 MWP2005에서 발표된 내용 중 효율적인 ROF 시스템 구현을 위해 필요한 MWP 소자 기술에 대한 내용을 소개하였다. MWP 2005에서는 특히 수 Gbps 이상의 정보를 밀리미터파 대역에서 보내기 위한 기술에 대해 다양하게 다뤄졌으며, 125GHz의 밀리미터파 신호 전송 실험 결과가 제시되었다. 또한 광섬유 링크를 통해 아날로그 신호 전송을 효율적으로 수행하기 위해, 높은 광 포화전력을 가지면서 기울기 효율이 우수한 전계흡수 변조기가 소개되었으며, 삽입손실이 크지 않으면서 전계흡수 변조기와 광검출기를 집적시킨 구조의 실험결과도 소개되었다. 또한 MWP 2005에서는 새로운 기술에 대한 소개 뿐 아니라 향후 4세대 이동통신 등에서 핵심 부품 기술로 자리잡을 수 있는 ROF 기술이 현실적으로 적용될 수 있는 경제적 방안에 대한 관심도 크게 증대되기도 하였다.

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A Frequency Stable and Tunable Optoelectronic Oscillator Using an Optical Phase Shifter and a Phase-shifted Fiber Bragg Grating

  • Wu, Zekun;Zhang, Jiahong;Wang, Yao
    • Current Optics and Photonics
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    • v.6 no.6
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    • pp.634-641
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    • 2022
  • A frequency stable and tunable optoelectronic oscillator (OEO) incorporating an optical phase shifter and a phase-shifted fiber Bragg grating (PS-FBG) is designed and analyzed. The frequency tunability of the OEO can be realized by using a tunable microwave photonic bandpass filter consisting of a PS-FBG, a phase modulator. The optical phase compensation loop is used to compensate for the phase variations of the RF signal from the OEO by adjusting an optical phase shifter. Simulation results demonstrate that the output RF signals of the OEO can be tuned in a frequency range of 118 MHz to 24.092 GHz. When the ambient temperature fluctuates within ±3.9 ℃, the frequency drifts of the output RF signals are less than 68 Hz, the side-mode suppression ratios are more than 69.39 dB, and the phase noise is less than -92.49 dBc/Hz at a 10 kHz offset frequency.

Broadband Instantaneous Frequency Measurement System Based on the Dual Paths of the Stimulated Brillouin Scattering Effect

  • Jiahong Zhang;Weijie Liao
    • Current Optics and Photonics
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    • v.7 no.4
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    • pp.378-386
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    • 2023
  • A wideband instantaneous frequency measurement (IFM) system is been proposed, designed and analyzed. Phase modulation to intensity modulation conversion is implemented based on the stimulated Brillouin scattering (SBS) effect, and the microwave frequency can be measured by detecting the change in output power. Theoretical analysis shows that the frequency measurement range can be extended to 4fb by adjusting the two sweeping signals of the phase modulators with a difference of 2fb. The IFM system is set up using VPI transmission maker software and the performances are simulated and analyzed. The simulation results show that the measurement range is 0.5-45.96 GHz with a maximum measurement error of less than 9.9 MHz. The proposed IFM system has a wider measurement range than the existing SBS-based IFM system.

Jitter Reduction by Modulator-Bias Control in Analog Fiber-Optic Links Employing a Mach-Zehnder Modulator Followed by an Erbium-Doped Fiber Amplifier (마하-젠더 광 변조기와 EDFA로 구성된 아날로그 광통신 링크에서 변조기 바이어스 조정을 이용한 랜덤 지터의 감소)

  • Lee, Min-Young;Yoon, Young-Min;Shin, Jong-Dug
    • Journal of IKEEE
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    • v.13 no.4
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    • pp.103-109
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    • 2009
  • We report an efficient jitter reduction technique in an analog fier-optic link employing a Mach-Zehnder modulator followed by an erbium-doped fiber amplifier. By adjusting the modulator-bias to $0.089V_{\pi}$, we could increase the RF gain up to 10.65 dB for 10 GHz RF signal and reduce the random jitter by 46.5%, max, at an input optical power of -0.11 dBm to the EDFA.

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Variable and Flexible Optical Frequency Comb Source using Dual Mach Zehnder Modulator and Phase Modulator

  • Naveed, Abbas;Choi, Bong-Soo;Tran, ThanhTuan;Seo, Dongsun
    • Journal of IKEEE
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    • v.20 no.4
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    • pp.385-391
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    • 2016
  • We demonstrated experimentally a variable optical frequency comb source using a cascaded dual parallel Mach Zehnder modulator (DPMZM) and a phase modulator (PM). With this simple configuration and applying low drive voltages, we generated variable comb source composed of spectral lines 3, 5, 7, 9 and 11 with 10-GHz frequency spacing, also generated 2 and 3 spectral lines with 20 GHz frequency spacing. The generated comb source maintains high spectral coherence across the entire bandwidth with good spectral flatness (within 1-dB for 2, 3, 5, 7 comb lines, within 2-dB for 9-comb lines and within 3-dB for 11 comb lines). The flat and variable comb source is mainly achieved by manipulating 6 operating parameters of DPMZM, setting RF amplifier gain, connected at phase modulator and phase shifters. Hence the method is simple and offers great flexibility in achieving flat and variable comb spectrum, which is experimentally demonstrated. This brings advantages of power efficiency due to low driving voltages, simplicity and cost effectiveness to the system.

Narrowband Modulation Response Enhancement Using a Dual-Electrode Distributed Feedback Laser Integrated With an Electro-Absorption Modulator (전계 흡수 변조기가 집적된 다중 전극 분포 궤환형 레이저를 이용한 광신호의 협대역 변조 응답 향상)

  • Cho, Jun-Hyung;Heo, Seo-Weon;Sung, Hyuk-Kee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.8
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    • pp.1968-1973
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    • 2013
  • We present the enhancement of narrowband modulation response of an optical source by integrating a dual-electrode distributed feedback (DFB) laser with an electro-absorption modulator (EAM). The dual-electrode DFB laser exhibits a multiple optical modes owing to a self-pulsation in GHz range. By modulating the laser and modulator sections of the integrated device simultaneously, 20-dB of narrowband modulation response enhancement at 6 GHz with 7-GHz tuning range has been observed.

Construction of an Optically Pumped Cesium Atomic Clock (광펌핑 세슘원자시계의 구성)

  • 이호성;오차환;양성훈
    • Korean Journal of Optics and Photonics
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    • v.3 no.2
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    • pp.123-132
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    • 1992
  • We designed and constructed the Cs beam tube which consists of a Ramsey cavity, four C-field rods, fluorescence detecting systems, and etc. for developing an optically pumped Cs atomic clock. A semiconductor laser was used for optical pumping and probing in the Cs beam. We observed Ramsey resonance signal by detecting the fluorescence signal in the probing region as the microwave frequency injected into the Ramsey cavity was scanned near 9192.6 MHz which corresponds to the "clock transition" of Cs atoms. We found that the linewidth of the Ramsey signal was 200 Hz, the magnetic field intensity was $8.61\muT$ when the current of 0.8A flowed in the C-field rods, and the second order Zeeman shift by the magnetic field was 3.17 Hz.s 3.17 Hz.

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Microwave Signal Spectrum Broadening System Based on Time Compression

  • Kong, Menglong;Tan, Zhongwei;Niu, Hui;Li, Hongbo;Gao, Hongpei
    • Current Optics and Photonics
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    • v.4 no.4
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    • pp.310-316
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    • 2020
  • We propose and experimentally demonstrate an all-optical radio frequency (RF) spectrum broadening system based on time compression. By utilizing the procedure of dispersion compensation values, the frequency domain is broadened by compressing the linear chirp optical pulse which has been multiplexed by the radio frequency. A detailed mathematical description elucidates that the time compression is a very preferred scheme for spectrum broadening. We also report experimental results to prove this method, magnification factor at 2.7, 8 and 11 have been tested with different dispersion values of fiber, the experimental results agree well with the theoretical results. The proposed system is flexible and the magnification factor is determined by the dispersion values, the proposed scheme is a linear system. In addition, the influence of key parameters, for instance optical bandwidth and the sideband suppression ratio (SSR), are discussed. Magnification factor 11 of the proposed system is demonstrated.