Abstract Advances in recent years on optical devices have enabled optical encoding-decoding technologies to be a reality nowadays. There are many applications where it is possible to use the processes of cod/decoding optics, but the best known is code division multiple access working on optical environment, known as OCDMA. This thesis presents a study of coherent OCDMA systems, covering two key aspects; modeling noise that interferes with target signal and design and implementation of fiber Bragg gratings devices as encoders/decoders. The noise modeling includes as many variables as possible in order to achieve a more accurate model. In this way, it considers from the bandwidth receiver until the state of signal polarization through the use of two types of modulation techniques in these systems, such as OOK (On-Off Keying )and DPSK (Differential Phase Shift Keying). Moreover, the fiber Bragg gratings are presented as the most promising devices for use in OCDMA, thanks to its versatility and optical fiber based device characteristics. For this reason, it has dedicated special attention to study its characteristics, emphasizing in particular its dependence with temperature and the relevance of the reflectivity on their behaviour to cod/decoded signals. Then a novel method of design, done through a process of synthesis, is presented, obtaining a high performance cod/decoding device. This thesis is also studying the encoding and decoding all optical labels in packet-switched networks. This application seeks to reduce processing times in currently optical nodes and it has been proposed a couple of years ago. Here we focus on two aspects, the first is based on the fact that autocorrelation peak obtained by the optical label processing can be reused for the formation of the new label assigned to the following packet to be sent. This proposal reduces the latency and costs of implementation. And second, the study of the dispersion effect on the encrypted signals that travel through fibre optics. In the last chapter of the thesis was carried out a description of the incoherent OCDMA systems, and a code in 2 dimensions was selected to show how is designed and its partial implementation of the system to verify the effect of interference on the target signal.