• 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.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.17-22
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• 2003

We experimentally measured the dependence of FWM efficiency on channel spacing for G.652, G.653, G.655 optical fiber with various dispersion values and compared the results with analytical results. Also, we investigated the dependence of XPM efficiency on channel spacing and dispersion in pump-probe experimental configuration.

• 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.

• 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.

• 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.

• 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.

• 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.

• Journal of Animal Environmental Science
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• v.11 no.1
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• pp.61-70
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• 2005

A total of 4 trials were conducted to evaluate the nutritional value of food waste-byproduct feeds mixture(FWM) rotary drum-pasteurized and cured, to trace the nutritional flow according to the processing stages and finally to determine the optimal mixing formulation of feed ingredients for the growing pigs. Pasteurizing and curing FWM using a rotary drum drier resulted in little change in chemical composition and 8 to $15 \%$ of dry matter losses. Chemical change was affected by different feed ingredients used in each trial. Curding of FWM was caused probably by high moisture content, starch content and(or) physical characteristics of feed ingredients. The optimal mixing ratio of feed ingredients was food waste 45 : deepstacked broiler litter 10 : bakery by-product 22.5 barley bran 22.5. In conclusion, FWM rotary drum-pasteurized and cured had a satisfactory feed-nutritional value far growing pigs.

• 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.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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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)