A ferrule-less optical backplane connector assembly includes a substrate having at least a pair of optical guide receiving structures formed therein, the pair of optical guide receiving structures further being formed at substantially a right angle with respect to one another so as to guide a corresponding first and second optical guide into optical alignment with one another. The signals received from the subtending edge nodes may be aggregated into signals that are channel switched by optical core nodes or by other shell nodes toward destination edge nodes. The three-dimensional bra underwire comprises the middle part and two ends of the underwire, wherein the underwire is a inclined-type underwire with a certain inclination angle, at least one end of the underwire is a flat section, while the other parts are inclined section, and the inclined section is connected with the flat section by a transition section. In a first set of four embodiments, a latch is formed in a first part of the locking mechanism and in a second set of four embodiments, the latch is formed in a second part of the locking mechanism. The harder metal surface provides a foundation for subsequent surface hardening such as coating with TiN.