A1 is a bend-insensitive single-mode optical fiber engineered specifically for access networks and FTTH deployments. Fully backward compatible with legacy G. D infrastructure, it supports full-band transmission from 1260nm to 1625nm. 652, which describes its characteristics, has been adapted to this experience. Designed for tight routing in data centers, FTTH, and space-constrained installations. 5mm, enabling routing around corners, through conduits. ITU-T (International Telecommunication Union) defines several single-mode fiber standards, including G.