G652D and G657A2 specifications refer to the glass and cable construction of optical fibre and are generally the fibres of choice in optical fibre patch leads for singlemode systems.

ITU-T G652D singlemode fibres have been used in all networks for more than 30 years. Being backwards compatible, this makes for easier maintenance/repair (splicing fibres of the same type). The G652D fibre ModeField Diameter is 10.4µm @1550nm.

G652D fibres provide marginally lower loss transmission, which is better in facilitating long distance communication links (up to and greaterthan 100km).

However, G652D fibres have limited bend resistance.

G657A2 fibres are used in advanced access cable network installation, where higher bend resistance is required for smaller cable jointing pits and also allows for cable and hardware miniaturisation.

G657A2 fibres are fully compatible with G652D fibres. The G657A2 fibre Mode Field Diameter is 9.8µm@1550nm. Splice losses are slightly higher when splicing the two different fibres together.

G657A2 fibre has greater resistance to bending (macrobend)losses (see figure below), and facilitating low-cost deployment techniques.