# How to configure an Optical Attenuator

You can calculate the optical attenuation based on the actual optical power.

The principle for determining whether an attenuator needs to be configured at a transmission point is as follows:

If P(out)max – S x Attenuation coefficient > P(in)max, an attenuator needs to be configured.

The optical attenuation is calculated in the following formula: T= P(out)max – S x Attenuation coefficient – P(in)max.

Table 1 Description of the Paramater

 Name Description P(in)min maximum transmit optical power. P(out)max transmission distance. S transmission distance. A attenuation coefficient. Note that the attenuation coefficient is related to optical fiber types and wavelengths. By default, the attenuation coefficient of a 1310-nm wavelength in a G.652 fiber is 0.45 dBm/km or 0.4 dBm/km; the attenuation coefficient of a 1550-nm wavelength in a G.652 fiber is 0.235 dBm/km or 0.25 dBm/km. P(in)max maximum receive optical power, that is, minimum overload point.

Table 2 Reference for configuring an attenuator:

 BOM Number Description P(out) P(out) P(in) P(in) max min min max 34060276 eSFP,1310nm,STM1,LC,SM,15km -8 dBm -15 dBm -31 dBm -8 dBm