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How To Divide O, E, S, C, L, U Bands In Optical Communication
Time: 2023-12-19
Transmission loss in optical fiber varies with the wavelength of light.
After continuous research and testing, scientists found that light in the 1260 nm ~ 1625 nm region has the smallest signal distortion and the lowest loss, making it the most suitable for optical fiber transmission.
Figure 1 Attenuation of Different Wavelengths in Optical Fiber Transmission
In May 2002, ITU‑T (Telecommunication Standardization Sector of the International Telecommunication Union) divided this low‑attenuation wavelength region (1260 nm ~ 1625 nm) into five bands: O, E, S, C, and L.
An additional U band is also commonly defined in the industry.
Table 1 Comparison of Optical Communication Bands
|
Band
|
Description
|
Wavelength Range
|
|
O band
|
Original
|
1260-1360 nm
|
|
E band
|
Extended
|
1360-1460 nm
|
|
S band
|
Short Wavelength
|
1460-1530 nm
|
|
C band
|
Conventional
|
1530-1565 nm
|
|
L band
|
Long Wavelength
|
1565-1625 nm
|
|
U band
|
Ultralong Wavelength
|
1625-1675 nm
|
O Band
The O band is the original wavelength band for optical communications, covering 1260 nm – 1360 nm.
It was the first band used in optical communication systems and features the lowest chromatic dispersion, resulting in minimal signal distortion.
E Band
The E band is the extended band, ranging from 1360 nm to 1460 nm.
It is the least commonly used among these bands.
It mainly serves as an extension of the O band but is rarely deployed, because many installed fiber cables exhibit high attenuation in this range, and the related manufacturing process is highly energy‑intensive, limiting its application.
S Band
The S band is the short‑wave band, covering 1460 nm – 1530 nm.
Its fiber loss is lower than that of the O band.
The S band is widely used in many PON (Passive Optical Network) systems.
C Band
The C band is the conventional band, spanning 1530 nm – 1565 nm.
It provides the lowest fiber loss and is highly advantageous for long‑haul transmission.
It is widely used in metro, long‑haul, ultra‑long‑haul and submarine optical transmission systems, often combined with WDM and EDFA technologies.
The development of DWDM (Dense Wavelength Division Multiplexing) has further expanded the application of the C band, enabling multiple signals to be transmitted over a single fiber.
L Band
The L band is the long‑wavelength band, covering 1565 nm – 1625 nm.
It is the second‑lowest loss band and is typically used when the C band cannot meet bandwidth requirements.
Supported by mature EDFA technology, DWDM systems have expanded upward into the L band.
It was initially used to increase the capacity of terrestrial DWDM networks and has since been adopted by submarine cable operators to expand total transmission capacity.
Since the C and L bands have the lowest transmission attenuation, DWDM systems mostly use wavelengths from these two bands.
U Band
Beyond the five main bands, the U band (ultra‑long‑wavelength) covers 1625 nm – 1675 nm.
It is mainly used for network monitoring and management applications.
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