how to determine whether the module is connect with single mode fiber or multimode fiber?

I have a SC interface optical transceiver, how to determine whether the module is connect with single mode fiber or multimode fiber?

Firstly, see the logo above the module, with words of “MM” said multi-mode, “SM” said single mode; with “850nm” means multi-mode, “1310nm or 1550nm” means single mode.

Secondly, you can use an optical power meter to test the module. If optical power is more than -20dBm, it means multi-mode. If it is between -1~-19dBm, it means single mode.

Thirdly, if it is a SFP transceiver module, you can also see the color of the clasp. Clasp with black color is multi-mode; clasp with other colors (like green, blue, yellow, etc.) is single mode.

Tags: fiber optical transceiver module