Attenuators

Attenuators are used with single-mode fibre optic devices and cable to filter the strength of the fibre optic signal. Depending on the type of attenuator attached to the devices at each end of the fibre optic cable, you can diminish the strength of the light signal a variable amount, measured in decibels (dBs).

Why would you want to filter the strength of the fibre optic signal?
Single-mode fibre is designed to carry a fibre optic signal long distances—as much as 70 kilometres. Fibre devices send this signal with great force to ensure that the signal, and your data, arrive at the other end intact.

But when two fibre devices connected with single-mode fibre cable are close to each other, the signal may be too strong. As a result, the light signal reflects back down the fibre cable. Data can be corrupted and transmissions can be faulty. A signal that is too strong can even damage the attached equipment.

Because it’s probably not feasible to move your fibre equipment farther apart, the easiest solution is to attach an attenuator to each fibre device. Just as sunglasses filter the strength of sunlight, attenuators filter the strength of the light signal transmitted along single-mode fibre cable. Within the attenuator, there’s doping that reduces the strength of the signal passing through the fibre connection and minute air gaps where the two fibres meet. Fibre grooves may also be intentionally misaligned by several microns—but only enough to slow the fibre optic signal to an acceptable rate as it travels down the cable.

Before selecting an attenuator, you need to check the type of adaptor on your fibre devices. Attenuators typically fit into any patch panel equipped with FC, SC or LC adaptors that contain either PC or APC contacts. In addition to the type of adaptor, you also need to determine the necessary attenuation value, such as 5 or 10 dB. This value varies, depending on the strength of fibre optic signal desired.

Learn more:
Fibre Optic Cable.