Disruptive Technologies
Passive Optical Networks

Optical fibers currently in the research and prototyping stages, such as hollow-core fibers, are now reaching maturity. Hollow-core fiber consists of several air channels or tubes surrounding a hollow core that can contain air, an inert gas, or a vacuum (Figure 30 ). Light in the main mode is guided through the air in the center, and secondary modes are confined to the periphery. Since the refractive index of air is approximately 1, while the refractive index...