communication - Does any satellite communicate only through laser?

The main reason for reduced received signal with radio communication in space is the spreading loss, that is intensity declines with the square of the distance from source to receiver. This is true even with beamed radio signals.

Laser communications beams suffer from exactly the same loss once the cross-sectional area of the beam exceeds size of the receiving sensor. Which for practical purposes will always be the case for space communications.

The comms. system you choose is more related to bandwidth, absorption losses, immunity to interference, the practicality of the technology, ... but not spreading losses.

For SETI laser communications signals will be more difficult to detect unless they are deliberated attempts to contact others by an alien civilisation own SETI program, as lasers usually have much narrower beam widths than radio transmitters.