The way I do it now is they have a Star Wars Encyclopedia. When asked in an interview his general opinion on the EU, he replied: It's unlikely that EU/Legends authors got the idea of a plasma-based lightsaber from Lucas since Lucas claimed he didn't know much about the EU: Wookieepedia's Legends article on lightsabers describes the lightsaber as plasma-based and cites the Legends novel Luke Skywalker and the Shadows of Mindor, which was released in 2008 (before Disney took over).

Note that plasma-based lightsabers were introduced in the old Expanded Universe (now branded 'Legends' by Disney). It seems that Lucas thought of both lightsabers and blasters as laser-based but Disney is changing them to be plasma-based. Similarly, blasters were originally described as lasers but have been retconned as beams of plasma in the Disney canon novel Lords of the Sith (the Episode VII script refers to blaster fire as lasers, though, so Disney's retcon isn't consistent). Episode VII was released under Disney, so evidently Disney is avoiding the 'laser sword' description. The phrase 'laser sword' is not used in the Episode VII script. The Episode III script, which was the last film under Lucas' control, uses the phrase seven times. This can be explained away in-universe as an ignorant young slave misunderstanding the physics of lightsabers, though it's a more prominent example of how Lucas interpreted lightsabers. you're a Jedi Knight, aren't you?ДЄNAKIN : I saw your laser sword. The phrase 'laser sword' is also spoken by a character at least once, by young Anakin Skywalker in Episode I:ДЄNAKIN. With astounding agility old Ben's laser sword sparks to life and in a flash an arm lies on the floor. The Episode IV script uses the phrase 'laser sword' three times, so Lucas evidently thought of lightsabers as laser-based from the beginning. The scripts for both the original trilogy and the prequels refer to lightsabers as 'laser swords'.

Script episode vii blueharvest