【正文】 . Input optical signal splits equally in the two arms of the MZIM which are actually EOPMs for modulating the phase of the optical carrier. At the output, the two arms are coupled either constructively or destructively to provide intensity modulated optical pulses. Fig. 1. Duo binary transmitter module with dualarm MZIM (T1). Fig. 2. Duo binary transmitter with singlearm MZIM delayandadd circuit (T2). 桂林電子科技大 學(xué)畢業(yè) 設(shè)計(jì)（論文）報(bào)告用紙 第 3 頁(yè) 共 29 頁(yè) Fig. 3. Duobinary transmitter with singlearm transmitter and filter circuit (T3). MZIM can be of two types: singlearm MZIM and dual arm MZIM. In singlearm MZIM only one single driving voltage is applied to the either arm of MZIM [9] and the output transmitted optical field Eo(t) is given as: Existence of the phase term in Eq. (3) shows that the chirping effect is present, thus we can say that the singlearm MZIM generated signals are not chirpfree. Particular structure of the MZIM can only minimize the chirping (xcut MZIM). It has been found that a small amount of chirp is useful for transmission [9]. Dualarm MZIM has push– pull arrangement where the dual drive voltages V1(t) and V2(t) are inverse to each other and thus, able to pletely eliminate the chirping effect in the modulation. The transmitted op tical field can be written as: Fig. 4. Comparison of 10 Gbps RZ duobinary transmitter modules 桂林電子科技大 學(xué)畢業(yè) 設(shè)計(jì)（論文）報(bào)告用紙 第 4 頁(yè) 共 29 頁(yè) Fig. 5. Comparison of 20 Gbps RZ duobinary transmitter modules. The use of optical duobinary transmitter with the dualarm MZIM is the usual choice in transmitter design at high data rate, however, dual arm configuration demands more stringent requirement of symmetry to be met [10]. Singlearm MZIM with duobinary filter can also be used where duobinary filter can be approximated by a low pass filter with halfpower cutoff at approximately one fourth the data rate. At this cutoff frequency, the spectral occupancy of the modulated optical field is restricted to [f0 177。rbert, . Elbers, G. Fischer:, SPMlimit of duobinary transmission, in: Proc. ECOC, Munich, Sep. 3– 7, Paper , 20xx. [3] L. Pierre, . Thiery, D. Penninckx, 243 km, 10 Gbit/s transmission experiment through standard ?bre and impact of self phase modulation using partial response scheme, Electron. 32 (March (7)) (1996) 673– 674. [4] M. Lax, Rate equations and amplitude noise, IEEE J. Quantum Electron. 3 (1967) 37– 46. [5] . Agrawal, Nonlinear Fiber Optics, Academic Press, New York, 1989. [6] . Agrawal, FiberOptic Communication Systems, Wiley, New York, 20xx. [7] . Kaminow, T. Li, Optical Fiber Communication, vol. IVA, Academic Press, Elsevier Science, San Diego, CA/New York, 20xx. [8] T. Kawanishi, T. Sakamoto, M. lzutsu, Highspeed control of lightwave amplitude, phase, and frequency by use of electrooptic effect, IEEE J. Selected Top. Quantum Electron. 13 (20xx) 93– 103. [9] . Binh, Optical Fiber Communication Systems: Overview of Modeling Techniques for Optical Transmission Systems, CRC Press, 20xx. [10] W. Kaiser, T. Wuth, M. Wichers, W. Rosenkranz, Reduced plexity optical duobinary 10 Gb/s transmitter setup resulting in an increased transmission distance, Photon. Technol. Lett. (20xx). [11] . Lee, . Messerschmitt, Digital Communication 2/e, Kluwer Academic Publishers, Norwell, MA, USA, 1994. 桂林電子科技大 學(xué)畢業(yè) 設(shè)計(jì)（論文）報(bào)告用紙 第 9 頁(yè) 共 29 頁(yè) Transmission performance on frequency response of receivers and chirping shape of transmitters for 10Gb ? s LiNbO3 modulator based lightwave systems AbstractWe report transmission performance depending on frequency response of receivers and chirping shape of transmitters for10Gb ? s LiNbO3 modulator based light wave systems. By solving the nonlinear Schrodinger equation including developed chirping and extinction ratio(ε) models for transmitters, and frequency response and noises for receivers, we have evaluated transmission performance by bit error rate ( BER ). and eye opening penalty ( EOP ). Calculated BER and EOP characteristics are pared to the measured BER characteristics so that we can find which bination between chirping model and frequency response for receivers is the best model to estimate the tendency in sensitivity degradation similar to the measured BER characteristics. The simulation results suggest that calculated BER characteristics using the Bessel–Thomson filter as a receiver frequency response model provide better prediction to estimate system performance. Furthermore, different chirping models may be used for positive and negative chirp parameters for better estimation of BER. 1 Introduction As current optical transmission systems are being more and more plex, and demand for munication services is growing at a higher speed than ever experienced before, simulation tools can provide efficient and fast system design, and therefore systems are implemented with less time and cost. So, many papers have been reported about light wave system simulations [1–10]. In highspeed optical transmission system, intensity modulated pulse is distorted by fiber dispersion, fiber nonlinearity, and transient chirping of transmitters. Moreover, frequency response characteristics of receivers have an important impact on the inter symbol interference at the input of the decision circuit, which can cause additional signal distortion. Therefore, in order to estimate accurate transmission performance, receiver charac