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What Is L Band and Other Optical Wavelength Bands?

Optical fibers are used to transmit information over long distances through light. As technologies have developed over time, fiber-based systems are becoming more popular for long-haul optical data transmission.

The capacity of fibers for data transmission is large and transmission capacities are very fast. The telecommunications industry use fiber optics because the attenuation is less at these wavelengths.

With optical fiber telecommunications system, a few transmission bands have been defined. In this article we look at what is L band and the other optical wavelength bands.

Optical Wavelength Bands


The wavelengths we use for transmission are used to test for losses. Everything designed or tested, when it comes to fiber optics, sits within the defined wavelengths.

Networks use light in the infrared region which has wavelengths longer than visible light. The defined optical wavelength bands sit between 850nm and 1675nm.

Optical wavelength bands are divided into the following:

Band Wavelength Range
O (original) band 1260-1360 nm
E (extended) band 1360-1460 nm
S (short wavelength) band 1460-1530 nm
C (conventional) band 1530-1565 nm
L (long wavelength) band 1565-1625 nm
U (ultra-long wavelength) band 1625-1675 nm

O Band

Original band (O band) ranges between 1260nm and 1360nm. In the 1970s, it was considered as the ‘original’ wavelength band because at the time, the lowest attenuation showed near this band.

O band is mainly used for high-speed Ethernet transmission and Passive-Optical Network (PON) systems. It offers high-speed optical transmission because of its small fiber dispersion.

E Band

Extended wavelength band (E band) has a wavelength range between 1360nm and 1460nm. Its wavelength range is between 5-3.33mm. The short wavelengths means that it is widely used for microwave backhaul links.

The E band beams are narrow to help minimise interference between sites. It is the least common wavelength band because of its high attenuation.

S Band

Short wavelength band (S band) is the frequency range that runs between 1460nm to 1530nm in the radio spectrum. Its wavelength range is between 15-7.5cm.

This band is used for many PON systems. It is commonly used for satellite communication and radar purposes by the shipping, aviation and space industries. Large antenna systems are needed for the best performance but the S band is efficient in supplying real-time data.

C Band

Conventional band (C band) ranges between 1530nm and 1565nm and has a wavelength range between 7.5-3.75cm. It is the most widely used band in optical communication and has been popular for decades.

C band is used for many satellite communication systems such as Wi-Fi and radar systems. In recent years, the band has been auctioned off all around the world for 5G purposes. The band is resilient and it well suited for subsea and other uses within the maritime industry.

L Band

Long wavelength band (L band) refers to the frequency range which runs from approximately 1565nm to 1625nm in the radio spectrum. Its wavelength range is between 30-15cm. Due to its frequency, the L band is a popular choice as it has a low bandwidth and is easy to implement.

This band is used for a wide range of applications such as radar, satellite and terrestrial communications. The low frequency range means that it is not suitable for streaming applications like video, voice and broadband connectivity. As this band is less susceptible to interruptions, it is most suited for operations management, remote monitoring and low orbit satellites.

L band is the least expensive band as it requires low-cost equipment. It has a wider beam width and so does not need a high-quality (and high costing) antenna to work efficiently.

U Band

Ultra-long wavelength band (U band) operates between 1635nm and 1675 nm. It is mainly used for network monitoring purposes.

We Can Support Your Fiber Optic Networks

At Carritech we support a wide range of fiber optic equipment for your network. We offer the full telecommunications solution with part supply, product repair, inventory management as well as ongoing support.

To view our stock, learn more about the equipment or enquire about purchasing, visit our products page.

For more information about our other services, please get in touch with the team through our online form, call (+44) 0203 006 1170 or email

Source: FiberLabs

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