Based on 40Gbit/s Return-to-zero differential phase-shift keying
(RZ-DPSK) DWDM system, the four dispersion
management programs are proposed to suppress optical pulse phase jitter induced by kerr nonlinear effect including the
self-phase modulation (SPM) and cross- phase modulation (XPM). The tolerance against the kerr nonlinear effect is
studied through detailed numerical simulation by Split-Step Fourier Method. The results are showed that there are more
than 2dB power penalty difference for different channels in a program and 5dB power penalty difference for different
compensation programs. Through appropriate selection, DPSK system must be having 2dB performance improvement.
Based on the analysis of the characteristic of ultrashort optical soliton, third-order dispersion (TOD ) and Raman scattering influences
were taken into account. The quantitative relationship between the self-frequency shifting with distance, pulse width and
TOD are found out using the Numerical simulation and fitting method. The size of the pulse time delay is also studied caused by the
self-frequency shifting. The results are obtained the quantitative relationships between the self-frequency shifting and pulse
time delay with distance, pulse width and TOD, which are very important for the high-speed optical switch.
The performance of WDM-based coherent time-spreading OCDMA system is studied. Upper bound and lower bound of
normalized throughput are obtained with 8 wavelength channels and 127 length and 511 length Gold codes. It is shown
that when all simultaneous users are equally allocated to different wavelength channels, WDM+ TS OCDMA has much
better performance. However, if there is no central control to allocate wavelength channels equally, WDM+ TS OCDMA
system has the in-between performance of normalized throughput.
The effects of the PMD and filter control in DMS system are studied theoretically with variational method. Firstly, the DMS transmission of filtering control in constant birefringence fibers is analyzed by Varitional method, from which the evolving rules of characteristically DMS parameters are obtained. Secondly, the stability of DMS transmission and its timing jitter are investigated in the random varying birefringence fibers. At the last, the mean square of DMS timing jitter is gotten, which can be simplfied to no filtering DMS system and to linear transmission systems in considering the effects of PMD. The results reveal that the condition of stability of filter control in DMS system must be satisfied with the relationship of filter strength kf < 2dyP3 Esol ÷ √πB4C2 + 2yP3 Esol C and DMS's timing jitter can be decreased considerably with help of filter strength.
The dispersion managed soliton transmission is a new soliton transmission scheme, but the ultra long-haul WDM system is limited its communication capability for multi-perturbations. In the present, the multi-perturbations including the amplificatory spontaneous emission (ASE) noise, across phase modulation (XPM) between the channels etc are considered. The evolvement characteristics of dispersion managed soliton transmission under control of inline filter are studied with variational method. Then the analysis expressions of timing jitter and equations of DMS's transmission
evolution are gotten. The analysis results indicate that the filter can increase the DMS's transmission rate and stabilize
DMS transmission. At same time, there exist a optimal configure scheme of filter strength and parameters of DMS. If
choosing the parameters (kf",C,B)reasonably, the pulse can be transmitted stable.
A scheme of WDM+OCDMA system employing optical hard-limiter(OHL) is proposed, and its performance of normalized throughput is analyzed. Upper bound of normalized throughput is obtained when all simultaneous users are equally allocated to different wavelength channels. Lower bound of normalized throughput is obtained when all simultaneous users are firstly allocated to same wavelength channels. Compared with the performance of WDM+OCDMA system without OHL, both upper bound and lower bound of normalized throughput in WDM+OCDMA system with OHL can be improved.
Interferometric noise(IN) is essential to an OCDMA system, since the tree topology of optical coder and decoder induces the multi-path transmission of signal from same laser. Signal noise ratio(SNR) including MAI, optical beat noise(OBN) and IN is firstly deduced in this paper. Numerical and experimental results show that in one
dimension OCDMA system with narrow line width laser, interferometric noise is great enough to limit system performance with relative high bite rate and small frequencies' difference; while in tow dimension OCDMA system, interferometric noise is a minor factor compared to OBN.
The performance of normalized throughput in WDM+OCDMA is compared with that of MW OCDMA system after considering the effect of chromatic dispersion. Normalized throughput in MW OCDMA system will be reduced after considering the effect of chromatic dispersion. Both WDM+OCDMA and MW OCDMA systems have comparable performance of normalized throughput when traffic load is light. However, WDM+OCDMA system has better performance when traffic load is heavy. Furthermore, the peaked normalized throughput of WDM+OCDMA system is
larger than that of MW OCDMA system.
The three allocated schemes of dispersion managed soliton transmission systems are proposed on standard single-mode fiber. Adopting variational method, the timing jitters induced from the perturbations of amplifier spontaneous-emission (ASE) noise and across-phase modulation (XPM) in multiplexed systems are studied. The results have shown that the dispersion management strength S must be satisfied 2
A new one-dimensional optical orthogonal codes named extend modified hyperbolic congruence codes(EMHC), is first constructed, and its performance is analyzed. Using EMHC for time spreading and prime codes (PC) for wavelength hopping, a new two-dimensional optical orthogonal codes named EMHC/PC is constructed. Then, the performance of EMHC/PC is analyzed, and is also compared with EQC/PC. It is shown that EMHC/PC has the same code cardinality and code length, but has better cyclic cross-correlation performance. Therefore, EMHC/PC can support more simultaneous users in optical CDMA networks.
Estimating the number of simultaneous users on channel, optimum threshold value in multi-wavelength optical CDMA(MW OCDMA) is achieved according to maximum likelihood principle. When MW OCDMA system has large number of simultaneous users on channel, optimum threshold value will vary with the number of simultaneous users, and
the receiver will adjust the optimum threshold accordingly. Theoretical analysis and analogy simulation show that BER of MW OCDMA system will degrade greatly when employing the proposed optimum threshold value by maximum likelihood principle.
The performance of normalized throughput in WDM+OCDMA system is studied. When all simultaneous users are equally allocated to different wavelength channels, upper bound of normalized throughput is obtained. When all simultaneous users are first allocated to same wavelength channels, lower bound of normalized throughput is obtained. However, if there is no central control to allocate wavelength channels equally, WDM+OCDMA system has the in-between performance of normalized throughput.
The performance of normalized throughput in a hybrid WDMA-OCDMA system is studied. Effect of optical beat noise and dispersion on the normalized throughput is analyzed. The scheme of BCH channel coding is proposed to improve the performance of a hybrid WDMA-OCDMA system. Analysis result shows that the normalized throughput can be improved greatly when traffic load is medium. Furthermore, the maximum normalized throughput will increase for the BCH-coded hybrid WDMA-OCDMA system