Development of Optical Code Division Multiple Access Based System Using Spectral Amplitude Coding via Fiber Bragg Gratings (FBGs)

The multiple user’s based transmission systems are developed in the past using various multiple access techniques for fibre optic communications. Among these multi-user systems, the transmission using Optical Code Division Multiple Access is widely used. Currently, many systems offer the codewords that are sent simultaneously over the fiber for active users. However, each technique has its own pros and cons. In this work, the orthogonal optical coding schemes are investigated and used in the developed new graphical user interface using Quadratic Congruence codes types. Furthermore, at the receiver, single-photodiode detection (SPD), AND subtraction and modified-AND subtraction technique are developed using Fiber Bragg Gratings (FBGs) for the first time. The designed FBGs based SPD detection has been identified as a better detection scheme compared to AND and modified-AND detection scheme used in balanced detection that is currently widely used. The designed FBGs based SPD is considered an effective way of detecting the received signals and cancelling of interference signals among multiple users. It also offers a reduction in the cost of the receiver and a reduction in shot noise because only one single photodiode is used. The justification of the developed system is examined using high data rate and an active number of users. It has been demonstrated that the designed system has a better presentation in accommodating an active number of user for a high data rate of Gbps. The system developed in this work will be help full in design and implementing the spectral amplitude coding- optical code division multiple access system for the transmission of data within a local area network. It will also assist to be familiar with the suitable number of network users and the expected high rate can be delivered.