Attenuators are passive devices used to reduce the amplitude of a light signal without significantly changing the wave itself. This method of attenuation allows higher performance than fibre splices, which function by misdirecting rather than absorbing the light signal.

Attenuators are often a requirement in applications where the receiver cannot accept the signal generated from a high-power light source. The plug type configuration makes it possible to use the attenuator directly on the ends of a patchcable and can as such be inserted into an adapter