Hi Sahil Singh
An optical circulator is a component that can be used to separate optical power that travels in opposite directions in one single fiber. An optical circulator is a three-port device that allows light to travel in only one direction from port 1 to port 2, then from port 2 to port 3.
As is evident from the definition above and mentioned by Fayiqa in earlier comment i believe it acts as an isolator but not as a power combiner.
Best Regards
Burhan