Corning SMF-28 ULL Bare Optical Fiber
SMF-28 ULL is Corning's ultra-low-loss fiber for long-haul terrestrial networks where span loss budgets are tight and every tenth of a dB per kilometer determines whether an amplification site is needed. Attenuation at 1550 nm is specified at 0.165 dB/km or below.
- ITU-T standard
- G.654.C / G.652.B
- Core composition
- Pure silica
- Mode field diameter
- 9.8–10.0 µm @ 1550 nm
- Attenuation @ 1550 nm
- ≤ 0.165 dB/km
Compliant with ITU-T G.654.C and G.652.B, SMF-28 ULL is built on a pure silica core design. Pure silica core fibers achieve lower Rayleigh scattering and lower intrinsic attenuation than conventional germanium-doped cores, which is the source of the ULL performance advantage. The tradeoff is a longer cable cutoff wavelength (≤1530 nm rather than ≤1260 nm for G.652), meaning the fiber is designed for C-band and L-band operation, not O-band.
Over a 400 km long-haul route, the difference between 0.165 dB/km and 0.200 dB/km is 14 dB of accumulated loss. That 14 dB can mean two fewer amplifier sites, each of which requires power infrastructure, maintenance, and real estate. The economic case for ULL fiber on long terrestrial routes is straightforward and has driven significant deployment over the past decade.
SMF-28 ULL is available with G.657.A1 bend compliance and in both 242 µm and 200 µm coating. The 200 µm variant is used in high-fiber-count cables for the same reasons as in the standard SMF-28 Ultra family.
Specifications
| ITU-T standard | G.654.C / G.652.B |
|---|---|
| Core composition | Pure silica |
| Mode field diameter | 9.8–10.0 µm @ 1550 nm |
| Attenuation @ 1550 nm | ≤ 0.165 dB/km |
| Effective area (Aeff) | ~80 µm² |
| PMD coefficient | ≤ 0.04 ps/√km |
| Cable cutoff | ≤ 1530 nm (C-band and above) |
Typical Applications
- Long-haul terrestrial DWDM routes where amplifier spacing is the cost driver
- Coherent 100G, 400G, and 800G submarine-connected terrestrial segments
- National backbone infrastructure requiring fewest regeneration sites
Why Order Corning Fiber from Aumictech?
We source directly from the Corning authorized channel. Every spool ships with documentation, including reel ID and fiber code.
0.5 km to 1,000 km on a single order. Mix lengths across spools. Choose FC, SC, or LC connectors per spool end, or leave ends bare.
Certificate of compliance and OTDR test data available on request. Required for carrier acceptance testing and network documentation.
Continental US next-day and two-day air available. International shipping on request. Most orders confirmed within one business day.
Frequently Asked Questions
Can SMF-28 ULL be used in O-band (1310 nm) systems?
No. The cable cutoff wavelength of G.654.C fiber is specified at 1530 nm, meaning single-mode propagation is only guaranteed above that wavelength. SMF-28 ULL is designed for C-band (1530-1565 nm) and L-band (1565-1625 nm) operation. For O-band systems, use G.652.D fiber such as SMF-28 Ultra.
What is the mode field diameter of SMF-28 ULL compared to G.652 fiber?
SMF-28 ULL has a mode field diameter of approximately 9.8-10.0 µm at 1550 nm, compared to 9.2 µm for G.652.D fibers at 1310 nm. The larger mode field gives higher effective area (about 80 µm²) and lower nonlinear impairments at high optical power. Splice loss to G.652.D fiber is slightly higher than same-type splices due to the MFD mismatch, typically 0.1-0.2 dB per splice.