Ji Jianhua

A New Family of two-dimensional Optical Orthogonal Codes EPC/OCS Based on Extend Prime Code and One-coincidence Sequence

A new two-dimensional optical orthogonal codes named EPC/OCS is first constructed, using EPC (extend prime code) for time-spreading and OCS (one-coincidence sequence) for wavelength-hopping. Cross-correlation performance of EPC/OCS is analyzed. Compared with MPHC, the number of wavelengths for EPC/OCS is not limit to a prime number. EPC/OCS can be constructed flexibly, and also can use available wavelengths adequately. When the number of wavelengths is large than a prime number, EPC/OCS not only has larger code cardinality, but also has better cross-correlation performance. Theoretical analysis shows that EPC/OCS can reduce the bit error rate (BER) of MW OCDMA networks

Phase Noise Monitor and Reduction by Parametric Saturation Approach in Phase Modulation Systems

Nonlinear phase noise (NLPN) is investigated theoretically and numerically to be mitigated by parametric saturation approach in DPSK systems. The nonlinear propagation equation that incorporates the phase of linear and nonlinear is analyzed with parametric saturation processing (PSP). The NLPN is picked and monitored with the power change factors in the DPSK system. This process can be realized by an optical PSP limiter and a novel apparatus with feedback MZI. The monitor range of phase noise is 0°–90°, which may be reduced to 0°–45° if the monitor factor is about the Stockes wave but not an anti-Stockes wave. It is shown that DPSK signal performance can be improved based on the parametric saturation approach.

Improvement of normalized throughput in WDM+OCDMA system using optical hard-limiters

A scheme of WDM+OCDMA system employing optical hard-limiter (OHL) is proposed, and its performance of normalized throughput is analyzed. The upper bound of the normalized throughput is obtained when all the simultaneous users are equally allocated to different wavelength channels. The lower bound of the normalized throughput is obtained when all the simultaneous users are firstly allocated to the same wavelength channels. Compared with the performance of WDM+OCDMA system without OHL, both the upper bound and lower bound of the normalized throughput in WDM+OCDMA system with OHL can be improved.