© 2021, Electromagnetics Academy. All rights reserved.We present the design, optimization, and analyses of efficient couplers to construct nano-optical transmission systems involving nanowires. The couplers consist of optimized arrangements of nanocubes and are integrated into critical locations, such as nanowire inputs, corners, and junctions, to improve electromagnetic transmission in accordance with design purposes. Optimization and numerical analyses are performed by employing an efficient simulation environment based on a full-wave solver and genetic algorithms. Using the designed couplers, we obtain various configurations that enable efficient transmission and distribution of input powers to multiple outputs. With their favorable properties, the designed couplers and constructed systems can be further used to build larger nanowire networks.