Bend Insensitive Single-mode Fibers are being broadly used to support the fiber to the home (FTTH) applications.
Along with extensive FTTH applications, the demand for fibers with a smaller bend radius is increasing. The fibers could be easily installed at a small angle, tight limited spaces of fiber distribution panels, termination boxes, wall mount outlets in the FTTx fiber access network, without causing higher attenuation of fiber in 1550nm wavelength.
ITU-T Standard
The ITU-T Recommendation for Bend Insensitive Single-mode Fibre is G.657.
G.657 fiber is divided into 2 main categories:
- G.657.A – Fibers for Access Networks
- G.657.B – Fibers for short distances at the end of Access Networks
Each Category of G.657 fiber is divided into 2 sub-categories:
- G657 A1 and G657 A2
- G657 B2 and G657 B3
The main difference between these sub-categories are the minimum bending radius:
| Fiber Type | Bend Radius |
| G657.A1 | 10mm |
| G657.A2, G657.B2 | 7.5mm |
| G657.B3 | 5.0mm |
The other category, G.657.B does not need to be compliant with G.652 fibers. Therefore G.657.B fibers are mostly used in indoor fiber optic cables that are installed with field-installable optical connectors.
Bend Insensitive Fiber Single-mode G.657