IridiumNEXT sats are 860kg.
SpaceX's 2 test satellites were 400 kg.
SpaceX's 2 test satellites were 400 kg.
The concept 'Size, Weight, and Power' (SWaP) is commonly used when comparing FSO vs. RF systems. Incidentally, FSO systems have lower SWaP than RF systems. They're smaller and lighter payloads, and the system requires less poweR.