In previous posts, we have used the term attenuation, but what is it? What does it mean and how does it affect my fiber optic link?
Attenuation is the loss of optical signal power in a fiber and is expressed in decibels (dB). The greater the attenuation, the more limited the length of the link becomes.
Loss or attenuation can be caused by intrinsic and extrinsic factors.
Intrinsic: These are all factors related to the fiber manufacturing process, such as impurities in the glass, geometric parameters (oval cores), and the materials from which the fiber is constructed, which can absorb or scatter part of the light.
Extrinsic: These are external factors that we add to the fiber, such as installation defects, macro and micro bends, improperly coupled fibers, dirt in connectors and splices, splitters, attenuators, among others.
All these factors consume signal power. In fact, every kilometer of fiber inherently has a loss per kilometer that must be taken into account when performing an optical loss budget.
Each event added to the fiber optic link increases attenuation and reduces optical power. Today, we have standards that provide us with the allowed values for each of these events. For example, a fusion splice should be approximately 0.1 dB to be considered normal or within parameters, while the connection of two connectors is 1 dB. However, these values will depend on the wavelength, as each has different sensitivity depending on the phenomenon or event.
It is worth mentioning that all communication links and connections suffer from attenuation; it is not exclusive to fiber optics. However, attenuation in a fiber optic link is less than in a wireless or copper link, which is why fiber optics has been prevalent in long-distance links.
