1. Optical fibers are generally cataloged by their construction characteristics and by the size of their core given in microns, the refractive index and the loss per km measured in decibels (db)

The best fibers for transport systems are those that have less loss per km.

2. The signals over the optical fiber are transported using DWDM (Dense Wave Division Multiplexing) technology: These signals are basically light signals with different wavelengths. To understand the concept of wavelength in a simple way, let’s think about colors, each shade of color that our eyes perceive has a different wavelength; So, we can differentiate between blue and red. In fiber optics, signals with different colors or wavelengths are used to transmit several signals over the same fiber wire.