Q1 : Does OPT52-31405STR supports 0 to 20km also?
As per specification it is given that it supports maximum 40KM. Is there any minimum distance required between two transceivers?

Ans: Thanks for your question, this transceiver supports transmission distance -3dBm, so for ultra-short distance, we suggest adding an attenuator of 5dB~10dB to avoid any overload. if you have any questions, please feel free to contact us.

Q2 : In continuation to above answer..
How distance can be considered as Ultra-short distance and respective attenuator dB, to avoid overload.
Also can you please suggest standard procedure for Surge Test over Optical Transciever.