What medium?
EM stands for Electromagnetic field. Visible light is simply one of the frequencies of that field that we happen to see. Much higher frequencies create particles.
I am not going anywhere with this. You just asked if photons came in different frequencies : ) I happen to like to take conversations tangentially off course. Sometimes if we look at what we are discussing from a different perspective it makes all the difference in the world.
I do know what EM stands for, and what it represents.
What I meant was a medium like ‘plasma’.
The EM field could be around an electrical motor, or around the Earth, or.... anything.
As a matter of fact, Particles can be made from ‘light’.
Sometimes, just looking at what we are discussing makes all the difference in the world (open the box)
That is the one thing we certainly have in common.