EXFO FTB -5240S/5240BP Optical Spectrum Analyzer - Manual (Page 168)

Setting Up the Instrument in DFB Mode
162 FTB-5240S/S-P/BP
Setting Up Acquisition Parameters
4. Select the wavelength range for your acquisition.
You can select the wavelength range by entering the start and stop values
or by selecting a range on the double slider.
To select the wavelength range using the double slider, move the left and
right handles on the double slider or simply click on any band.
Note: You can select more than one adjoining ranges to include in your range, for
example, S + C.
The wavelength range covered within these bands of the spectra are listed
below.

O band (original): 1255 to 1365 nm

E band (extended): 1355 to 1465 nm

S band (short wavelengths): 1455 to 1535 nm

C band (conventional “erbium window”): 1525 to 1570 nm

L band (long wavelengths): 1560 to 1630 nm

U band (ultralong wavelengths): 1620 to 1650 nm.