• Title, Summary, Keyword: Four-Wave Mixing(FWM)

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Impact of Four Wave Mixing on Manchester Coded ASK Multichannel Optical Communication System (Manchester Coded ASK 다중채널 광통신 시스템의 Four Wave Mixing 에 대한 영향)

  • Lee, Ho-Joon;Leonid G. Kazovsky
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.18 no.11
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    • pp.1607-1617
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    • 1993
  • The performance of Manchester-coded ASK optical wavelength division multiplexing(WDM) systems is evaluated laking into account the shot noise and the four wave mixing(FWM) caused by fiber nonlinearities. The result is compared to conventional non-return-to-zero(NRZ) systems for ASK modulation formats. Further, the dynamic range, defined as the ratio of the maximum input power(limited by the FWM), to the minimum input power(limited by receiver sensitivity), is evaluated. For 1.55 rm 16 channel WDM systems, the dynamic range of ASK Manchester coded systems shows a 2.0 dB improvement with respect to the NRZ. This result holds true for both dispersion-shifted fiber and conventional fiber it has been obtained for 10 GHz channel spacing, 1 Gbps/channel bit rate.

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Characteristics of Compensation for Distorted WDM Channel with Inter-channel Interference due to Four-Wave Mixing (4-광파 혼합에 의한 채널 간섭이 존재하는 왜곡된 WDM 채널의 보상 특성)

  • 이성렬;손성찬;방효창;김지웅;조경룡
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.8 no.6
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    • pp.1234-1242
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    • 2004
  • In this paper, the characteristics of compensation for interferenced mid-channel signal by neighbor channels through four-wave mixing (FWM) process dominantly is investigated as a function of channel input power, fiber dispersion coefficient and transmission length in WDM system with equally spaced channels. The compensation method used in this research is mid-span spectral inversion(MSSI). The highly nonlinear dispersion shifted fiber (HNL-DSF) is used as a nonlinear medium of optical phase conjugator (OPC) in order to compensate wideband WDM signals. First, we confirmed that the effect of FWM on channel interference is gradually reduced as fiber dispersion coefficient becomes gradually smaller, independent of signal format. And, we confirmed that RZ is better than NRZ as a modulation format for transmitting high power channel with allowable reception quality. But realization of flexible WDM systems regardless of channel number variation is possible by using NRZ rather than RZ format.

Evaluation of Chromatic-Dispersion-Dependent Four-Wave-Mixing Efficiency in Hydrogenated Amorphous Silicon Waveguides

  • Kim, Dong Wook;Jeong, Heung Sun;Jeon, Sang Chul;Park, Sang Hyun;Yoo, Dong Eun;Kim, Ki Nam;An, Shin Mo;Lee, El-Hang;Kim, Kyong Hon
    • Journal of the Optical Society of Korea
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    • v.17 no.5
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    • pp.433-440
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    • 2013
  • We present an experimental and numerical study of spectral profiles of effective group indices of hydrogenated amorphous silicon (a-Si:H) waveguides and of their chromatic-dispersion effect on the four-wave-mixing (FWM) signal generation. The a-Si:H waveguides of 220-nm thickness and three different widths of 400, 450 and 500 nm were fabricated by using the conventional CMOS device processes on a $2-{\mu}m$ thick $SiO_2$ bottom layer deposited on 8-inch Si wafers. Mach-Zehnder interferometers (MZIs) were formed with the a-Si:H waveguides, and used for precise measurement of the effective group indices and thus for determination of the spectral profile of the waveguides' chromatic dispersion. The wavelength ranges for the FWM-signal generation were about 45, 75 and 55 nm for the 400-, 450- and 500-nm-wide waveguides, respectively, at the pump wavelength of 1532 nm. A widest wavelength range for the efficient FWM process was observed with the 450-nm-wide waveguide having a zero-dispersion near the pump wavelength.

Characteristics of Compensation for WDM Transmission with Equally Spaced Channels using Mid-Span Spectral Inversion (채널 간격이 일정한 WDM 전송에서의 Mid-Span Spectral Inversion을 이용한 보상 특성)

  • 이성렬;임황빈
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.6
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    • pp.619-626
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    • 2004
  • In this paper, we investigated the compensation characteristics of distorted 16-channel WDM signal due to chromatic dispersion self phase modulation(SPM) and four-wave mixing(FWM). The bit rate and uniform frequency spacing of WDM channels are assumed to be 40 Gbps and 100 ㎓, respectively. The compensation method used in this approach is mid- span spectral inversion(MSSI), Highly-nonlinear dispersion shifted fiber(HNL-DSF) is used as a nonlinear medium of optical phase conjugator(On) in order to widely compensate WDM signal band. We confirmed that applying MSSI in WDM channels within special input power level compensates overall interferenced channels mainly due to FWM. But for long wavelength WDM channels having lower conjugated light power with respect to signal light power, compensation quality is deteriorated as dispersion coefficient of fiber becomes higher. Consequently, we confirmed that it is effective D apply MSSI with HNL-DSF as a nonlinear medium of OPC to WDM transmission link with relative small dispersion in order to compensate equally spaced WDM channels.

Impact of FWM on manchester coded DPSK WDM communication systems (Manchester coded DPSK WIDM 통신 시스템에서 FWM의 영향)

  • 이호준
    • Korean Journal of Optics and Photonics
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    • v.5 no.2
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    • pp.319-325
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    • 1994
  • The performance of Manchester-coded DPSK optical wavelength division multiplexing (WDM) systems using a stochastic approach is evaluated taking into account the shot noise and the four-wave mixing (FWM) caused by fiber nonlinearities. The result of Manchester-coded system is compared to conventional non-return-to-zero (NRZ) systems for DPSK modulation formats. Further, the dynamic range, defined as the ratio of the maximum input power (limited by the FWM), to the minimum input power (limited by receiver sensitivity), is evaluated. For $1.55.{\mu}m$16 channel WDM systems, the dynamic range of DPSK Manchester coded systems shows a 2.1 dB improvement with respect to the NRZ. This result holds true for both dispersion-shifted fiber and conventional fiber; it has been obtained for 10 GHz channel spacing, 1 Gbps/channel bit rate.t rate.

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Reception Performance Improvement of the Long-Haul WDM System with the Channel Interference Due to FWM Effect through the Power Symmetric Mid-Span Spectral Inversion (FWM에 의한 채널 간섭이 존재하는 장거리 WDM 시스템에서의 전력 대칭 MSSI 보상법을 통한 수신 성능 개선)

  • 이성렬;장원호;이윤현
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.13 no.7
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    • pp.716-725
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    • 2002
  • In this paper, we showed the applicability of power symmetric MSSI(Mid-Span Spectral Inversion) to the long-haul WDM system with the channel interference due to FWM(Four Wave Mixing). And we showed the degree of performance improvement. We used 1 dB EOP(Eye-Opening Penalty) criterion so as to evaluate the degree of compensation dependent on the variation of chirp parameter of optical pulse for the various input power in high speed tansmission system. And we evaluated the maximum input power of channel be able to be the signal to crosstalk noise (SNR) above 20 dB in the transmission link with the channel interference due to FWM. Consequently the proposed MSSI compensation method is capable to transmitting the total 68 WDM channels simultaneously with a 0.4 nm channel spacing and 5.3 dBm maximum input power in a 10 Gbps transmission link. Therefore the proposed power symmetric MSSI compensation method may be very useful for the implementation of long-haul wideband WDM transmission systems with relatively high power and improved performance.

Measurement of linear dispersion of optical fibers in zero-dispersion wavelength region (분산천이 광섬유의 영분산 파장영역에서 선형분산 곡선측정)

  • 김동환;김상혁;조재철;최상삼
    • Korean Journal of Optics and Photonics
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    • v.9 no.1
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    • pp.20-24
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    • 1998
  • Fiber four-wave mixing(FWM) in zero-dispersion wavelength region is studied. FWM efficiency of -26 dBm and bandwidth of 2nm are measured. The linear dispersion slope in zero-dispersion wavelength region is calculated from the modulation behavior of FWM efficiency.

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Realization of High Speed All-Optical Half Adder and Half Subtractor Using SOA Based Logic Gates

  • Singh, Simranjit;Kaler, Rajinder Singh;Kaur, Rupinder
    • Journal of the Optical Society of Korea
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    • v.18 no.6
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    • pp.639-645
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    • 2014
  • In this paper, the scheme of a single module for simultaneous operation of all-optical computing circuits, namely half adder and half subtractor, are realized using semiconductor optical amplifier (SOA) based logic gates. Optical XOR gate by employing a SOA based Mach-Zehnder interferometer (MZI) configuration is used to get the sum and difference outputs. A carry signal is generated using a SOA-four wave mixing (FWM) based AND gate, whereas, the borrow is generated by employing the SOA-cross gain modulation (XGM) effect. The obtained results confirm the feasibility of our configuration by proving the good level of quality factor i.e. ~5.5, 9.95 and 12.51 for sum/difference, carry and borrow, respectively at 0 dBm of input power.

Dephasing of continuum transitions induced by an electric field in semiconductor superlattices (초격자 반도체에서 전기장에 의한 Continuum Transitions들의 Dephasing)

  • 제구출;박승한
    • Proceedings of the Optical Society of Korea Conference
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    • pp.26-27
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    • 2000
  • 층 성장 방향으로 정전기장을 걸어준 GaAs/AlGaAs 초격자 반도체에서, 두 개의 100 fs 광학 펄스에 의해 생성된 four-wave-mixing(FWM) 신호의 dephasing 현상을 반도체 블록 방정식을 사용해서 분석하고자 한다. 이 FWM 신호의 이완은 전하-전하와 전하-포논 충돌과 같은 phase-breaking 충돌 과정들에 의해서 야기되는 비선형적인 광분극의 dephasing에 의해서 결정되어 진다.$^{(1)}$ 이 비선형적인 광분극은 펄스들에 의해서 동시에 여기되어 나타나는 자유전하 분극과 엑시톤 분극으로 구성되는데, 이 두 분극의 이완시간 특성은 서로 다른 거동을 보인다.$^{(2,3)}$ GaAs/AlGaAs 초격자 반도체에서 이 자유 전하 분극의 dephasing이 엑시톤 분극의 dephasing 보다 훨씬 빠르게 일어나고, 엑시톤이 자유 전하의 특성을 갖게 될수록, 즉 온도가 높을수록 또 엑시톤이 3차원의 특성을 가질수록 이 dephasing은 빠르게 일어난다.$^{(4)}$ (중략)

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All-optical wavelength conversion of 2.5 Gb/s optical signals by four-wave mixing in a semiconductor optical amplifier (반도체 광 증폭기내에서의 4광파 혼합을 이용한 2.5Gb/s 광신호의 전광 파장변환)

  • 방준학;서완석;이성은
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.35D no.8
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    • pp.69-75
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    • 1998
  • We demonstrate wavelength conversion of 2.5Gb/s optical signals by four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). We investigate the effect of input pump and signal powers on the coversion efficiency, optical signal-to-noise ratio (OSNR) and extinction ratio to be a measure of performance in a wavelength converter. As a result, we show that the maximum bit error rate (BER) performance can be obtained by co promising among high-vonversion efficiency (minimum Pprobe), high-OSNR (maximum Pprobe) and low-cross-gain saturation effects (Pprobe kept at least 6dB weaker than Ppump). In our experiment, we obtain optimum performance at +3 dBm pump power and -6dBm signal power. The power penalty incurred in the wavelength conversion can be minimized by careful selection of the input pump and signal powers. We show that about 0.5dB power penalty for 3.2nm wavelength coversion at 10-10 BER is achievable.

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