The spectrum for transmission in singlemode optical fibers has been
broken into the following wavelength ranges, or bands. Typically, the
wavelengths transmitted in multimode fibers are around 850 and 1310 nm,
known originally as first window and second window.
Wavelength Range Band Name In Nanometers (nm) O-band Original 1260 - 1360 E-band Extended 1360 - 1460 S-band Short 1460 - 1530 C-band Conventional 1530 - 1565 L-band Long 1565 - 1625 U-band Ultra-long 1625 - 1675