• Title/Summary/Keyword: Optical modulation

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Simulation of IMD3 induced CIR for analog optical transmission systems (아날로그 광 전송 시스템에서의 IMD3에 의한 CIR 시뮬레이션)

  • Jang, Seung-Hyun;Lee, Chul-Soo;Seol, Dong-Min;Jung, Eui-Suk;Kim, Byoung-Whi
    • Proceedings of the KIEE Conference
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    • pp.475-477
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    • 2005
  • We simulated 3rd order intermodulation distortion (IMD3) induced Carrier-to-Intermodulation Ratio (CIR) of laser diodes over a wide range of optical modulation index, and compared the results with commercial IMD3 induced CIR specification such as Composite Triple Beat (CTB) of DFB laser transmitter for CATV networks. It shows that the simulation results are in good agreement with the CATV CTB specification within 3dB margin. The results can be used to predict IMD3 induced CIR performance for various analog optical transmission systems with given optical modulation index and the number of transmission channels.

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Characterization of $V_2O_5$ thin films as a counter electrode for complementary electrochromic devices (상보형 전기변색소자용 $V_2O_5$박막의 대향전극 특성)

  • 조봉희;김영호
    • Electrical & Electronic Materials
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    • v.9 no.7
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    • pp.690-695
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    • 1996
  • We have systematically investigated the characterization of V$_{2}$O$_{5}$ thin films as a counter electrode for lithium based complementary electrochromic devices. The V$_{2}$O$_{5}$ thin films were prepared by thermal vacuum evaporation with varing the substrate temperature and film thickness. In electrochromic devices for smart windows, the WO$_{3}$ thin films with 400-800 nm thickness require to be capable of reversibly injection 10-15 mC/cm$^{2}$ of lithium, which is readily accomplished charge-balanced switching in a V$_{2}$O$_{5}$ thin films with 100-150nm thick. The V$_{2}$O$_{5}$ thin films produces considerably small changes in optical modulation properties in the visible and near infrared region(500-1100 nm) compared to the amorphous WO$_{3}$ thin films on 10-15 mC/cm$^{2}$ of lithium injection and the V$_{2}$O$_{5}$ thin films can therefore act as a counter electrode to WO$_{3}$ in a lithium based complementary clectrochromic devices. After 10$^{5}$ coloration/bleaching switching time, the degradation does not occurs and the devices exhibit a stable optical modulation in V$_{2}$O$_{5}$ thin films. It has shown that the injected lithium ion amounts in crystalline V$_{2}$O$_{5}$ thin films with the same thickness is large by 3-5 mC/cm$^{2}$ of lithium compared to the amorphous thin films in the same driving conditions. Therefore, to optimize the device performance, it is necessary to choose an appropriate film thickness and crystallinity of V$_{2}$O$_{5}$ for amorphous WO$_{3}$ film thickness as a working electrode.

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Analysis of Fiber-optic Link Budget for Optically fed Wireless Communication

  • Kim, Jung-Tae
    • Journal of information and communication convergence engineering
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    • v.1 no.1
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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.

Effects of Optically-modulated Metal-graphene Contact on the Photoresponsivity of Graphene Photodetectors (빛에 의해 변조되는 금속-그래핀 컨택이 그래핀 포토디텍터의 광응답도에 미치는 영향)

  • Lee, Chang-Ju;Shim, Jae Hoon;Park, Hongsik
    • Journal of Sensor Science and Technology
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    • v.28 no.2
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    • pp.117-120
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    • 2019
  • Graphene is recognized as a promising material for silicon photonics, since it has a wide optical-window that entirely covers the optical communication wavelength region ($1.3{\sim}1.6-{\mu}m$) and extremely high-carrier mobility that makes it possible to fabricate the high-speed photodetectors. However, the maximum absorbance of monolayer graphene is only 2.3%, which limits the photoresponse characteristics of graphene photodetectors. As a result, a low photoresponsivity of graphene photodetector is a critical issue limiting the use of graphene photodetectors in the optical communications field. In this paper, we investigated effects of optically-modulated metal-graphene contact on the photoresponsivity of graphene photodetectors. The optical modulation of the contact resistance mainly determined the photoresponse characteristics of graphene photodetectors. The Ni-contact graphene photodetector which has a characteristic of the significant optical modulation of metal-graphene contact showed a higher photoresponsivity than the Pd-contact device. This work will provide a way to improve the photoresponse characteristics of graphene-based photodetector and contribute to the development of high-speed/high-responsivity graphene photodetector.

Optical modulation of interconnection strength using amorphous $As_2S_3$ thin film (비정질 $As_2S_3$ 박막을 이용한 광연결 세기의 변조방식)

  • 김홍만
    • Proceedings of the Optical Society of Korea Conference
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    • pp.215-218
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    • 1990
  • A method for optical representation and modulation of synaptic interconnections between neurons using photoanisotropic amorphous As2S3 thin film is discussed. Experimental results show that the proposed method can be used for the representation of not only excitatory synaptic connections but also inhibitory synaptic connections. Applications of the method to the implementation of optical learning machine is also discussed.

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Fabrication of Optical fSDF Filter Using $As_2S_3$ Thin Film ($As_2S_3$ 박막을 이용한 광 fSDF 필터 제작)

  • 정재우
    • Proceedings of the Optical Society of Korea Conference
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    • pp.98-101
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    • 1991
  • The As2S3 thin film has a characteristics of optical modulation in both amplitude and phase. Since the As2S3 thin film can be used as a real-time reconfigurable optical filter, the fSDF filter can be optically fabricated on it. According to the modulation characteristics of the As2S3, the optimal fSDF filter recorded on this thin plate has the form of continuous amplitude and binary phase. Computer simulation and optical experiments on the optical pattern classification show that the As2S3 is suitable for the optical fSDF filter.

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Optical Harmonic Modulation-Demodulation Techniques for High-Speed Light wave Transmission

  • Choi, Young-Kyu
    • Journal of information and communication convergence engineering
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    • v.6 no.2
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    • pp.192-197
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    • 2008
  • High-speed harmonic optical modulation-demodulation schemes are presented and a possibility of the schemes for applying to high-speed light wave transmission system is tested at microwave frequency range. An example of this concept is as follows : Light wave is modulated succeedingly through cascaded optical modulators by a sub-carrier to produce a modulated light wave at harmonic frequency which is higher than the feasible frequency of the individual modulators. For demodulation of the base-band signal, the high frequency optical sub-carrier is down-converted by the same kind of optical modulator with the same concept of harmonic modulation.

Optical modulation characteristics of resonant tunneling diode oscillator (빛에 의한 공명투과다이오드 진동자의 주파수 변조 특성)

  • 추혜용;이일희
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.10
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    • pp.139-143
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    • 1996
  • We report on the static and dynamic characteristics of optically modulated resonant tunneling diode oscillator (RTDO) formed in double-barrier quantum-well structure. Under the illumination of Ti:Sapphire laser, the dc current-voltage (I-V) curves of RTDO shifted towared lower voltages. This characteristic was found to odify the series resistance, negtive differential resistance, capacitance, and the inductance of the RTDO. As a result, the resonant frequency of TRDO centered at 5.302 GHz was found to decrease about 20 MHz under the laser illumination. At a constnat bias voltage, the oscillation frequency decreased linearly as the laser power was increased.

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Implementation of the Optimized Phase-type High Resolution Spatial Light Modulator and Analysis of its Characteristics (최적화된 위상형 고해상 공간 광변조기의 구현 및 특성분석)

  • Ko, Jung-Hwan
    • 전자공학회논문지 IE
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    • v.45 no.1
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    • pp.7-14
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    • 2008
  • In this paper, a new high resolution XGA-SLM is implemented through modification of a commercial TFT-LCD beam projector and its optical modulation characteristics as a spatial light modulator(SLM) is also analyzed. That is, the optics module, projection lamp and fans are removed from a commercial beam projector and instead, some electric circuits to compensate their removal are manufactured and then, by inserting them into the beam projector, a new XGA-SLM is finally implemented. From some characteristic experimental results of the implemented high resolution TFT-LCD SLM, the proposed TFT-SLM is found to have an good optical linearity in amplitude and phase modulation characteristics as a function of the input gray levels. Especially, through implementation of the suggested TFT-LCD panel, the implemented SLM is proposed as a new relatively low-cost and high resolution SLM for optical information processing.