In this study, an analysis of the optical performance of two types of distributed Bragg reflector structures based on GaAs and InP material systems was carried out. The structures were designed for maximum performance at 4 µm with their reflectivity achieving between 80 and 90% with eight pairs of constituent layers. To further enhance the performance of these structures, additional Au layers were added at the bottom of the structure with Ti pre-coating applied to improve the adhesivity of the Au to the semiconductor substrate. The optimal range of Ti layer thickness resulting in the improvement of the maximum reflectivity was determined to be in between 5 and 15 nm.

The integration of optical fibre communication with multiple input multiple output-non-orthogonal multiple access (MIMO-NOMA) waveforms in cognitive radio (CR) systems is examined in this study. The proposed system leverages the advantages of optical fibre, including high bandwidth and immunity to electromagnetic interference to facilitate the transmission and reception of MIMO-NOMA signals in a CR environment. Moreover, MIMO-NOMA signal was detected and analysed by the hybrid-discrete cosine transform-Welch (H-DCT-W) method. Based on the modes results, a detection probability greater than 0.96%, a false alarm probability equal to 0.06, and a global system error probability equal to 0.09% were obtained with a signal-to-noise ratio (SNR) less than 0 dB, while maintaining a simple level of complexity. The results obtained in this paper indicate the potential of the optical fibre-based MIMO-NOMA system based on H-DCT-W technology in CR networks. Therefore, its suitability for practical CR applications is demonstrated by the improvements obtained in false alarms, detection probability, and error rates at low levels of SNR. This study contributes to the development of efficient and reliable wireless communication systems by linking cooperation and synergy concerning MIMO-NOMA, optical fibres, as well as the proposed detection technique (H-DCT-W).