Cisco SFP-10G-LR minimum distance
Cisco SFP-10G-LR module is capable of working with a link length of up to 10 km on any basic single-mode fibre. It complies with the 10GBASE-LR standard and uses 1310nm lasers. In this article Cisco SFP-10G-LR module is based on EDGE Optic’s part number 10G-SFP-10 (10km version) and 10G-SFP-20 (20km version) and all technical assumptions are based on EDGE Optic’s module parameters. It has following optical parameters from EDGE Optic’s matching product 10G-SFP-10:
As we see maximum transmitting power is -0.5dBm and receiver overload starts at 0.5dBm. Based on this if we would make connection using short distance single mode cable, even couple of meters it won`t do any harm and would not burn down the receiver side laser.