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Chromatic and temperature induced dispersion can both severely affect incoherent high data rate communications in optical fibre. This is certainly also true for incoherent optical code division multiple access (OCDMA) systems with multi-wavelength picosecond code carriers. Here, even a relatively small deviation from a fully dispersion compensated transmission link can strongly impact the overall system performance, the number of simultaneous users, and the system cardinality due to the recovered OCDMA auto-correlation being strongly distorted, time-skewed, and having its full width at half maximum (FWHM) value changed. It is therefore imperative to have a simple tunable means for controlling fibre chromatic or temperature induced dispersion with high sub-picosecond accuracy. To help address this issue, we have investigated experimentally and by simulations the use of a semiconductor optical amplifier (SOA) for its ability to control the chirp of the passing optical signal (OCDMA codes) and to exploit the SOA ability for dispersion management of a fibre link in an incoherent OCDMA system. Our investigation is done using a 19.5 km long fibre transmission link that is exposed to different temperatures (20 °C and 50 °C) using an environmental chamber. By placing the SOA on a transmission site and using it to manipulate the code carrier’s chirp via SOA bias adjustments, we have shown that this approach can successfully control the overall fibre link dispersion, and it can also mitigate the impact on the received OCDMA auto-correlation and its FWHM. The experimental data obtained are in a very good agreement with our simulation results.

Optical code division multiple access (OCDMA) is one of the promising technologies to be implemented using all-optical networks. The performance of OCDMA system is largely dependent on the particular codes used for encoding. A proper choice of code family as well as code dimension is of prime importance due to various transmitter and receiver design considerations. This paper mainly aims at evaluation of desirable characteristics of various spreading codes based on the prime sequences. An extensive effort has been done in this paper to evaluate the correlation characteristics of various types of one-dimensional (1-D), 2-D and 3-D prime codes for OCDMA communication system. The detailed mathematical modelling has also been explained. It is observed that an addition in coding dimension leads to significant improvement in the code characteristics.

In this paper, we propose a novel approach to realize the optical code division multiple access (OCDMA) system based on modified three-dimensional (3-D) multicarrier prime code. We exploit the advantages of spatial division multiplexing and consider modes as the third dimension. A simulation setup of the proposed 3-D OCDMA system is simulated for eight users for prime number (P = 3) at 7 Gbps and performance analysis is carried out in terms of BER, Q factor and number of users supported. Further, the BER of the proposed system for six users is varied from 1.00E −31 to 1.00E −9 for optical fibre of length 20–60 km at the given bit rate.

In this paper we investigate the family of prime codes 1D, 2D and 3D code for Optical CDMA communication system. Optical CDMA network works on the concept of assigning minimal interfering code sequence to each user that will intelligently route the traffic within the network. The 1D and 2D codes are compared with the proposed 3D codes based on prime sequence algorithm. The mathematically modeling of the codes is explained in detail. The orthogonality among codes is evaluated in terms of auto and cross correlation function on MATLAB. It is seen that the correlation property of the proposed 3D code is matched closely with the 1D code and better then the 2D Code. The cardinality of 3D code is better than the 1D code and almost comparable to the 2D code. The significance of introducing the dimension is explained in terms of BER versus number of user for 1D and 2D codes.