The first and tricky step is to solder SFP modules. The module pin outs is as follows. I need to solder 20 connectors with 20 wires to a standard 1.5mm pin outs. I used Mikrotik S-31DLC20D, a 1.25G SFP transceiver with a 1310nm Dual LC connector, for up to 20 kilometer Single Mode fiber connections, with DDM. But you may use any SFP module without problem.
Another reason I used Dual connector (TX and RX are different fiber interfaces) is to control TX function as additional. Thus, meter can transmit laser source and enable and disable this.
A good ref for SFP modules pin outs from finisar is here:
1) Standard SFP pinouts is as follows.
2) Soldering and result is as follow. We can omitted Data TX/RX pair pins for now.
Next is interfacing with Arduino