On a drama or stage show, there's always a person takes care of the lighting effects, but I don't know how to express that occupation. Does anyone know what it's called?
The term "lighting technician" would probably be apt for a theatre or stage show.
People who work on stage lighting are commonly referred to as lighting technicians.
You asked for a shorter of more informal term, there is also the term gaffer.
A gaffer in the motion picture industry and on a television crew is the head electrician, responsible for the execution (and sometimes the design) of the lighting plan for a production.
However the definition of gaffer seems to always be given as a person on a movie or television set.
In video, television, and film productions, lighting technicians work under the direction of the gaffer or chief lighting technician who takes their direction from the cinematographer.
Also, note that "gaffer" isn't that common outside its respective industry. So if you're going to use it for a casual/everyday audience/readership, they probably won't know what you're talking about.