Shuwen Yang

The analysis of all-optical logic gates based with tunable femtosecond soliton self-frequency shift

A type of tunable femtosecond soliton logic gate based on fiber Raman Self-Frequency Shift (SFS) is studied in this paper. The Raman SFSs of femtosecond solitons governed by the Newtons cradle mechanism in logic gate are analyzed with an Improved Split-Step Fast Fourier Transform (ISSFFT) algorithm. The impact factors of the solitonic pulse frequency shift and temporal time shift, which are included the Third-Order Dispersion (TOD) effect, are investigated. The existing theoretical equation of SFS is modified into a new expression for this type of soliton logic gate. A lower switching power and the small size of the soliton logic gate device is designed to realize the logic functions of AND, NOT, and XOR. The results demonstrate that the logic gate based on SFS is belonged to the asynchronous system and can be achieved with Milli-Watt switching power and good extinction ratio. ISSFFT is effective and accurately to analyze higher-order dispersive and nonlinear effects in the logic gates.

Construction and performance analysis of a 2D optical orthogonal code

Feature Issue on Optical Code Division Multiple AccessWhat we believe to be a new 2D optical orthogonal code, named PC/OCS, is constructed using PC (prime code) for time spreading and OCS (one-coincidence sequence) for wavelength hopping. Cross-correlation performance of PC/OCS is analyzed. Compared with PC/PC, the number of wavelengths for PC/OCS is not limited to a prime number. PC/OCS can be constructed flexibly and also can use available wavelengths effectively. When the number of available wavelengths is larger than a prime number, PC/OCS not only has a larger code cardinality than PC/PC, but it also has a better cross-correlation performance. Theoretical analysis shows that PC/OCS can reduce the bit error rate and enhance system throughput of multiple-wavelength (MW) optical code-division multiple access networks. When the number of available wavelengths is 16 and code length is 121, code cardinality of PC/OCS can increase approximately 17% more than that of PC/PC, and the peaked throughput can increase approximately 20%.

Code sequence analysis in asynchronous coherent time-spreading optical code-division multiple access

An analysis of the code parameters that are important to asynchronous coherent time-spreading optical code-division multiple-access (OCDMA) systems employing Gold codes is presented. Multiple-access interference (MAI) and beat noise (BN) are analyzed according to the aperiodic cross-correlation function. The relationship between the mean intensity of aperiodic cross-correlation and MAI and BN is deduced. Considering the mean system performance, MAI and BN can be calculated directly from the aperiodic autocorrelation function, and the aperiodic cross-correlation function is not needed. Hence, a computational saving can be achieved. Considering the worst system performance, the upper bound of the bit-error-rate performance is evaluated by the maximum value of the mean intensity of aperiodic cross correlation. For a 511 length Gold sequence, a coherent time-spreading OCDMA system can support 12 interfering users for the mean performance. However, an OCDMA system can support fewer than five interfering users in the worst performance.

Analysis of the code parameters in asynchronous coherent time-spreading optical CDMA system

An analysis of the code parameters that are important to asynchronous coherent time-spreading OCDMA system is presented. Relationship between the mean intensity of aperiodic cross-correlation and multiple-access interference (MAI) and beat noise (BN) is deduced. Considering the mean system performance, MAI and BN can be calculated directly from aperiodic auto-correlation function, and the aperiodic cross-correlation function is not needed. Hence, a computational saving can be achieved For 511 length Gold sequence, coherent time-spreading OCDMA system can support 12 interfering users for the mean performance.

Performance comparison of WDM+OCDMA and multi-wavelength OCDMA systems

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.

A new family of two-dimensional optical orthogonal codes with zero cross-correlation zone

A new family of two-dimensional optical orthogonal code with zero cross-correlation zone (2-D ZCZ) is constructed, using primary LA sequence for time spreading and OCS (one-coincidence sequence) for wavelength hopping. Performances of autocorrelation and cross-correlation of 2-D ZCZ are analyzed. BER performance of two-dimensional OCDMA system is also analyzed.

Construction and Analysis of a Novel 2-D Optical Orthogonal Codes Based on Modified One-coincidence Sequence

Abstract A new two-dimensional OOC (optical orthogonal codes) named PC/MOCS is constructed, using PC (prime code) for time spreading and MOCS (modified one-coincidence sequence) for wavelength hopping. Compared with PC/PC, the number of wavelengths for PC/MOCS is not limited to a prime number. Compared with PC/OCS, the length of MOCS need not be expanded to the same length of PC. PC/MOCS can be constructed flexibly, and also can use available wavelengths effectively. Theoretical analysis shows that PC/MOCS can reduce the bit error rate (BER) of OCDMA system, and can support more users than PC/PC and PC/OCS.

Research on multi-access interference in 2.5 Gb/s symbol overlapping optical fast frequency-hopping CDMA system

Optical encoders/decoders based on fiber gratings are designed and fabricated. Experiment on one interference user 2.5Gb/s symbol overlapping optical fast frequency-hopping CDMA (SO-FFH OCDMA) system is demonstrated. Multiaccess interference in SO-FFH OCDMA system is studied, and is compared with that of traditional FFH OCDMA system. Experiment result shows that multi-access interference will degrade the system performance. With one interference user, SO-FFH OCDMA can also decode data correctly at data bit rate 2.5Gb/s.

Upper boundary of BER performance in asynchronous coherent time-spreading optical CDMA system

Multiple-access interference (MAI) and beat noise (BN) are analyzed in asynchronous coherent time-spreading OCDMA system according to the aperiodic cross-correlation function. Relationship between the mean intensity of aperiodic crosscorrelation and MAI and BN is deduced. Considering the worst system performance, upper bound of BER performance is evaluated by the maximum value of the mean intensity of aperiodic cross-correlation. For 511 length Gold sequence, coherent time-spreading OCDMA system can support less than 5 interfering users in the worst performance.

The optimal dispersion management strength and transmission schemes in multiplexed disperison managed soliton systems

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 SPIE/OSA/IEEE Asia Communications and Photonics ACP 75 2005-11-06|2005-11-10 Asia-Pacific Optical Communications AOC05 630100 Shanghai, China Optical Transmission, Switching, and Subsystems III 6021 Poster Session 13