G.657.A2 fiber — factory-direct supply to Europe
ITU-T G.652.D / G.657.A2 compliant. 7.5 mm minimum bend radius. ≤0.21 dB/km at 1550 nm. Full-band operation 1260–1625 nm. Fully backward-compatible with installed G.652.D infrastructure. Sourced direct from ISO 9001-certified manufacturers in China — with full technical documentation.
The bend-radius problem that causes data centre outages
Standard G.652.D fiber has a minimum bend radius of 30 mm. In practice, patch cords inside racks, overhead trays, and under raised floors are routinely bent tighter than this — not deliberately, but because the space does not allow it.
When a single-mode fiber is bent beyond its rated radius, light leaks from the core. The result is increased attenuation, link budget failures, and intermittent signal errors that are almost impossible to diagnose without removing and re-routing every affected cable.
G.657.A2 moves the safe bend limit to 7.5 mm — a quarter of the G.652.D minimum. That margin eliminates the bend-induced loss problem entirely in realistic data centre routing scenarios, while remaining fully compatible with existing G.652.D links, splices, and transceiver infrastructure.
Full technical specification
Attenuation
| Parameter | Wavelength | Unit | Value |
|---|---|---|---|
| Attenuation | 1310 nm | dB/km | ≤0.35 |
| Attenuation | 1383 nm | dB/km | ≤0.35 |
| Attenuation | 1550 nm | dB/km | ≤0.21 |
| Attenuation | 1625 nm | dB/km | ≤0.24 |
| Attenuation vs. wavelength (1285–1330 nm vs. 1310 nm) | — | dB/km | ≤0.04 |
| Attenuation vs. wavelength (1525–1575 nm vs. 1550 nm) | — | dB/km | ≤0.03 |
| Attenuation discontinuity | 1310 / 1550 nm | dB | ≤0.05 |
Transmission characteristics
| Parameter | Condition | Unit | Value |
|---|---|---|---|
| Zero dispersion wavelength | — | nm | 1300–1324 |
| Zero dispersion slope | — | ps/(nm²·km) | ≤0.092 |
| Max PMD (individual fiber) | — | ps/√km | ≤0.2 |
| Cable cutoff wavelength (λcc) | — | nm | ≤1260 |
| Mode field diameter | 1310 nm | µm | 8.6 ± 0.4 |
Macrobending attenuation
The defining characteristic of G.657.A2 — enabling tight-radius routing in data centres, FTTx deployments, and in-building cabling.
| Bend radius | Turns | Wavelength | Unit | Max loss |
|---|---|---|---|---|
| 15 mm | 10 | 1550 nm | dB | ≤0.03 |
| 15 mm | 10 | 1625 nm | dB | ≤0.1 |
| 10 mm | 1 | 1550 nm | dB | ≤0.1 |
| 10 mm | 1 | 1625 nm | dB | ≤0.2 |
| 7.5 mm | 1 | 1550 nm | dB | ≤0.5 |
| 7.5 mm | 1 | 1625 nm | dB | ≤1.0 |
Geometrical characteristics
| Parameter | Unit | Value |
|---|---|---|
| Cladding diameter | µm | 125 ± 0.7 |
| Core-cladding concentricity error | µm | ≤0.5 |
| Cladding non-circularity | % | ≤1.0 |
| Coating diameter | µm | 245 ± 10 |
| Coating non-circularity | % | ≤4 |
| Coating-cladding concentricity error | µm | ≤12.5 |
Environmental characteristics
| Parameter | Condition | Unit | Max additional loss |
|---|---|---|---|
| Temperature cycling | –60°C to +85°C | dB/km | ≤0.05 |
| High temp. & high humidity | 85°C, RH 85%, 30 days | dB/km | ≤0.05 |
| Water immersion | 23°C, 30 days | dB/km | ≤0.05 |
| Dry heat aging | 85°C, 30 days | dB/km | ≤0.05 |
Complete optical, geometrical, mechanical, and environmental data
Where G.657.A2 is specified
Hyperscale & AI data centres
GPU clusters and AI training racks require extreme-density patching between top-of-rack switches, spine layers, and core routers. G.657.A2 handles the tight routing inside racks, overhead cable trays, and under-floor pathways that would cause signal loss with G.652.D.
- Intra-rack and inter-rack patch cords
- MTP/MPO trunk cables and harnesses
- Pre-terminated cross-connect panels
FTTH and FTTx drop cables
Last-drop fiber — from street cabinet to building entry point and through internal riser shafts — is routed around corners, through conduits, and under doors where a 30 mm bend radius is physically impossible. G.657.A2 enables FTTH operators to route through constrained building paths without signal penalty.
- MDU (multi-dwelling unit) internal drops
- Micro-duct blown fiber for FTTH
- ONT and home gateway pigtails
In-building and campus cabling
Office buildings, colocation facilities, and enterprise campuses route fiber through riser shafts, conduits, cable trays, and trunking systems that impose bend constraints on every run. G.657.A2 allows installers to route more directly without de-rating the link budget.
- Horizontal and vertical riser cables
- IDF-to-rack distribution runs
- Patch cords in congested racks
Industrial and smart building networks
Factory automation, warehouse management systems, and smart building infrastructure connect back to private or hybrid cloud environments through internal fiber networks where routing flexibility matters more than long-haul transmission distance.
- Industrial IoT network backbone
- Building management system cabling
- Tight-conduit factory floor runs
AI data centres and GPU clusters are the primary driver of G.657.A2 demand growth in 2026. High-density rack configurations make bend-insensitive fiber the only viable specification for intra-rack and cross-connect patching — G.652.D's 30 mm bend radius cannot be maintained in practice at this density.
Supply tightness and what it means for procurement
G.657.A2 fiber supply has tightened significantly in 2026. The primary driver is AI data centre build-out — hyperscale operators and cloud providers deploying GPU clusters at scale have locked in long-term manufacturing agreements with major fiber producers. This has reduced spot market availability and pushed distributor pricing above factory-gate levels.
The global fiber optic cable market is growing at approximately 8.45% CAGR through 2031, with G.657.A2 and G.657.A1 increasingly becoming the default specification for indoor single-mode cabling in new data centre builds and retrofits. G.657.A2 carries a moderate cost premium over G.652.D — typically in the range of tens of percent — but remains significantly less expensive than G.657.B3, which requires sacrificing full G.652.D backward-compatibility.
For procurement teams, factory-direct supply provides access to production capacity outside the spot market and eliminates the European distributor margin layer that compounds pricing during periods of supply tightness.
Enquire about availability →G.657.A2 fiber — frequently asked questions
What is G.657.A2 fiber and what makes it bend-insensitive?
G.657.A2 is a single-mode optical fiber standard defined by ITU-T that specifies significantly improved macrobending performance compared to standard G.652.D fiber. A G.657.A2 fiber maintains acceptable signal loss at a bend radius as small as 7.5 mm — versus the 30 mm minimum for standard G.652. This is achieved through a modified refractive index profile (typically a trench-assisted or hole-assisted design) that confines the optical mode more tightly, preventing light from leaking when the fiber is bent around tight corners. G.657.A2 is fully backward-compatible with G.652.D.
What is the difference between G.657.A1 and G.657.A2?
Both G.657.A1 and G.657.A2 are bend-insensitive single-mode fibers fully compatible with G.652.D. G.657.A1 is rated for a 10 mm minimum bend radius. G.657.A2 is rated for 7.5 mm — 25% tighter. For high-density data centre environments where patch cords are routed through tight spaces, G.657.A2's tighter tolerance provides a meaningful safety margin. G.657.A2 carries a small premium over G.657.A1 but is significantly cheaper than G.657.B3 (5 mm radius, non-G.652 compatible), making it the industry sweet spot for most data centre and FTTH applications.
Is G.657.A2 fiber compatible with existing G.652.D infrastructure?
Yes — fully. G.657.A2 conforms to G.652.D specifications for mode field diameter, cutoff wavelength, and transmission characteristics. It can be fusion-spliced to G.652.D fiber with negligible splice loss and used with all transceivers, connectors, and test equipment designed for G.652.D. This makes G.657.A2 a drop-in upgrade for applications needing tighter bend performance without replacing the installed backbone.
Why is G.657.A2 fiber supply tight in 2026?
The primary driver is rapid AI data centre and GPU cluster deployment globally. These facilities require extremely high-density fiber patching — thousands of patch cords routed through tight spaces inside racks and trays — where G.657.A2's 7.5 mm bend radius is essential. Large hyperscale operators have locked in long-term supply agreements, reducing spot availability. Factory-direct supply through Ériu Sourcing provides access to production capacity outside the spot market.
What connector types and reel configurations are available?
G.657.A2 fiber is available as bare fiber on reels with a 245 µm nominal coating diameter, compliant with ITU-T G.657.A2 and IEC 60793-2-50 B6.a2. Contact us with your specific reel length, fiber count, coating requirements, and application. We source factory configurations to match your production or installation needs.
G.657.A2 fiber — factory-gate pricing, direct to your European port
Share your specification: fiber quantity, reel configuration, delivery port, and timeline. We come back with a factory-direct quotation and lead time.
Also available: OPGW-24 G.652 ULL optical ground wire →