optical fiber

This term refers to the physical medium used in high-speed data transmission. In technical contexts, it is often used interchangeably with "fiber optics," though the latter typically refers to the broader field of science and technology rather than the individual strands themselves.

As a material noun, it is frequently treated as uncountable when referring to the technology or the substance in general (e.g., "the cable is made of optical fiber"). However, it can be used as a countable noun when referring to individual strands or specific types of fibers within a bundle.