ITU standards are also International Telecommunication Union standards (International Telecommunication Union, referred to as ITU). The Chinese name of ITU-T is the International Telecommunication Union Telecommunication Standardization Sector (ITU Telecommunication Standardization Sector).
In order to make the optical fiber have a unified international standard, ITU-T has developed a unified optical fiber standard (G standard). According to the ITU-T recommendations on optical fibers, the types of optical fibers are divided into seven categories. Within each of these major categories there are subcategories.
G.651 fiber (multimode graded index fiber)
single mode fiber
G.652 (dispersion non-shifted single-mode fiber)
G.653 (Dispersion Shifted Fiber)
G.654 (cutoff wavelength shifted fiber)
G.655 (Non-Zero Dispersion Shifted Fiber)
G.656 (Low Slope Non-Zero Dispersion Shifted Fiber)
G.657 (bend resistant fiber)