One fiber free and still need a 1G link? A BiDi SFP transmits and receives over a single single-mode fiber, on two wavelengths: 1310 and 1490 nm up to 40 km, 1490 and 1550 nm for 80 km. You always order them as a pair: a U module at one end and a D module at the other. Two identical modules won't give you link.
We supply pairs for 20, 40 and 80 km, with a simplex LC connector and coded for your platform: Cisco, Juniper, Arista, MikroTik, Ubiquiti and more. Pick the smallest reach that covers your distance; an optic that is too strong for a short link needs an attenuator. The product page shows what you get per variant. Need 10G? See 10G BiDi.
Fiber at home and want to replace your provider's box? That only works on AON. First check which SFP your fiber connection needs.