Final answer:
The state-of-the-art ground-to-ground communications infrastructure designed to exchange secure and non-secure voice, data, and video communications is optical fiber communication systems.
Step-by-step explanation:
The function described in the question is optical fiber communication systems. These systems use optical fibers to carry telephone conversations and Internet communications. Optical fibers offer advantages over traditional electrical-based systems, such as low loss, high bandwidth, and reduced crosstalk. They allow for secure and non-secure voice, data, and video communications through line-of-sight (LOS), satellite, or hard-wired resources.