What is C-band after all? What’s L-band or U-band? Here in our CATV products range, and elsewhere on web you will see those terms. This is a topic of today’s blog post.
The development of the transmission equipment for the fiber optic networks has been progressing very fast over last few years. New types of networks allow longer distances, higher speeds and WDM (wavelength-division multiplexing). These changes result in new wavelength ranges, which are called bands.
Original single mode fiber has been developed for the 850 nm lasers. It has evolved into “O-band” using glass fiber with wavelengths in a range from 1260-1360 nm with 1310 nm diode lasers.
The “C-band” has been developed in order to use 1550 nm wavelengths with low loss. The influence of the “C-band” has increased after repeaters have been replaced with fiber amplifiers. With the introduction of DWDM (dense wavelength-division multiplexing) the impact of the “C-band” became even greater due the ability to share single fiber using multiple wavelengths.
New fiber amplifiers help using DWDM technology in upper “L-band”.
FTTP PON is using low-cost type of WDM and is not requiring any additional equipment like amplifiers due the short range. On the other hand, it allows to have broad “band” choice – 1310 nm upstream and 1490 nm downstream. For the analog TV signal it also might use 1550 nm downstream, but since most of countries have switched to IPTV it is not very demanding.
Also there is a development of the “E-band” taking place between “O-band” and “S-band” but it is not getting any popularity due the heavy process of manufacturing.
Band Name
Wavelengths
Description
O-band
1260 – 1360 nm
Original band, PON upstream
E-band
1360 – 1460 nm
Water peak band
S-band
1460 – 1530 nm
PON downstream
C-band
1530 – 1565 nm
Lowest attenuation, original DWDM band, compatible with fiber amplifiers, CATV
