| Full title | Characteristics of a single-mode optical fibre and cable |
| Publisher | ITU-T Study Group 15 |
| Current edition | Edition 10.0, approved 29 August 2024 (G.652 08/2024) |
| Status | In force. Replaces G.652 (11/2016) |
| Categories in current text | G.652.B and G.652.D (A and C remain in the 2009 edition) |
| Related standards | ITU-T G.657, G.650.1, G.650.2; IEC 60793-2-50 (B-652.D); ISO/IEC 11801-1 |
What it covers
ITU-T G.652 describes the geometrical, mechanical and transmission attributes of a single-mode optical fibre and cable with its zero-dispersion wavelength around 1310 nm. It was first published in 1984. The fibre was originally optimised for the 1310 nm region but can also be used at 1550 nm.
It groups requirements into three kinds of attribute:
- Fibre attributes, which survive cabling and installation (mode field diameter, cladding, cut-off, macrobending, dispersion).
- Cable attributes, for cable as delivered (attenuation and PMD).
- Link attributes, for concatenated cables, given as design information in Appendix I.
Test methods and definitions are in ITU-T G.650.1 and G.650.2.
The four categories
The categories are mainly distinguished by their attenuation requirement at 1383 nm, the water peak region, and by their PMD limit.
| Category | Main difference | Where specified |
|---|---|---|
| G.652.A | No 1383 nm attenuation limit; PMD 0.5 ps/√km | 2009 edition only |
| G.652.B | No 1383 nm attenuation limit; attenuation specified at 1310, 1550 and 1625 nm; PMD 0.20 ps/√km | Current Table 1 |
| G.652.C | Low water peak, specified 1310 to 1625 nm; PMD 0.5 ps/√km | 2009 edition only |
| G.652.D | Low water peak, specified 1310 to 1625 nm; PMD 0.20 ps/√km | Current Table 2 |
Since the 2016 edition, only Tables 1 (G.652.B) and 2 (G.652.D) are printed. G.652.D allows use across the extended range from 1260 nm to 1625 nm, covering the O, E, S, C and L bands.
G.652.D recommended values
Fibre attributes
| Attribute | Value |
|---|---|
| Mode field diameter at 1310 nm | Nominal 8.6 to 9.2 µm, tolerance ±0.4 µm |
| Cladding diameter | 125.0 µm ± 0.7 µm |
| Core concentricity error | ≤ 0.6 µm |
| Cladding non-circularity | ≤ 1.0% |
| Cable cut-off wavelength | ≤ 1260 nm |
| Macrobending loss | ≤ 0.1 dB at 1625 nm, 100 turns at 30 mm radius |
| Proof stress | ≥ 0.69 GPa |
| Zero-dispersion wavelength | 1300 to 1324 nm |
| Zero-dispersion slope | 0.073 to 0.092 ps/(nm² × km) |
| Chromatic dispersion at 1550 nm | 13.3 to 18.6 ps/(nm × km) |
| Chromatic dispersion at 1625 nm | 17.2 to 23.7 ps/(nm × km) |
Cable attributes
| Attribute | Value |
|---|---|
| Attenuation, 1310 to 1625 nm | ≤ 0.40 dB/km |
| Attenuation at 1383 nm ± 3 nm, after hydrogen ageing | ≤ 0.40 dB/km |
| Attenuation, 1530 to 1565 nm | ≤ 0.30 dB/km |
| PMD link design value (PMDQ) | ≤ 0.20 ps/√km, for M = 20 cables, Q = 0.01% |
The attenuation range can be extended down to 1260 nm by adding 0.07 dB/km to the 1310 nm value, to allow for Rayleigh scattering. For comparison, G.652.B allows 0.35 dB/km at 1550 nm and its MFD range is wider, 8.6 to 9.5 µm with ±0.6 µm tolerance.
Notes that matter in buildings
- The cabled attenuation values are not meant for short cables such as jumpers, indoor cables and drop cables. The Recommendation cites IEC 60794-2-11, which allows indoor cable up to 1.0 dB/km at 1310 nm and 1550 nm.
- PMDQ is also not applied to jumpers, indoor cables and drop cables. It matters for long links with many spliced cable lengths.
- Cut-off wavelength depends on length and bending. For very short pieces, under 22 m without bends, the cut-off under the actual conditions should be checked.
- Products are expected to comply with the edition in force when they were made, so older installed fibre may meet an earlier version only.
How it relates to other standards
| Standard | Relationship |
|---|---|
| IEC 60793-2-50 | IEC product specification for class B single-mode fibres. G.652.D corresponds to category B-652.D |
| ITU-T G.657 | Bend-insensitive fibre. G.657.A fibres are a subset of G.652.D and fully compliant with it |
| ISO/IEC 11801-1 / EN 50173-1 | Define cabled single-mode categories such as OS2 (0.4 dB/km) for generic cabling. OS2 cable datasheets commonly quote G.652.D or G.657.A fibre |
| ITU-T G.650.1 / G.650.2 | Definitions and test methods for the attributes in G.652 |
In practice, a datasheet that says “G.652.D” or “B-652.D” is describing the same fibre type.
What to check on a datasheet
- The category, not just “G.652”. G.652.D is the low water peak, low PMD version.
- Cabled attenuation at 1310 nm and 1550 nm, and whether the figure applies to the cable type you are buying.
- Mode field diameter at 1310 nm, which affects splice loss between fibres from different makers.
- Whether the fibre is also G.657.A1 or A2, if tight bends are expected in enclosures or patch panels.
Related reading: Single-mode vs multimode fibre: OM3, OM4 and OS2 explained · Fibre optic loss budget: how to calculate insertion loss.