Zero Attenuation Fiber Optics (ZAFO) is a type of optical fiber.
Optical fiber is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data rates) than wire cables.
A ZAFO cable appears as a normal single-mode fiber optic line. The jacket, buffer and cladding are all routine and the core fiber is 8 microns across which is normal. Its core index of refraction is 1.458, a little higher than normal, however it has zero attenuation or transmission loss, whereas a high-end fiber optic cable has an attenuation of 0.4 decibels per kilometer. While most fiber optic lines can be a maximum of 15 kilometers long and must use signal repeaters for long distances, a ZAFO cable can be as long as needed and does not require the use of repeaters.
ZAFO is manufactured with a glass core that has traces of tantalum, lithium, and germanium. Its crystalline quartz-like structure only forms at 0.216 of Earth gravity. It is impossible to make on Earth, but can be manufactured in orbit or on the Moon with the use of a centrifuge.