Receiver overload
A long-reach module on a short path can saturate the receiver. Check the maximum input power and add an attenuator when the received level is too high.
Calculator
Will the link
actually close?
A listed reach is a specification, not a promise about your fibre plant. Work out the loss first — it takes a minute and it is the single most common reason an optic “does not work”.
Limits
What the calculator does not decide.
Dispersion
Above 10 Gb/s and beyond roughly 40 km, chromatic dispersion can limit the link before loss does. Confirm the dispersion tolerance for the planned distance.
Host support
A closed optical budget does not prove the host accepts the module. Coding, port configuration and software version are confirmed separately.
Installed reality
Route length, patch panels, old connectors and repairs all differ from the drawing. Use a measured loss test where you can.
Next
Turn the number into a shortlist.
Shortlist by reach
Filter the catalogue by data rate, distance and media.
Read the method
The full guide works through single-mode and multimode examples.
Ask for a review
Send your measured loss or route details and we will suggest what fits.
Next step
Send us the path, we will suggest the optics.
Share the route length, fibre type and measured loss if you have it, and we will shortlist suitable products.