That is actually where I went to look for Bab5 and couldn't find anything relevant for the Neutron-Laser, or even a mention, Minbari or otherwise.
But note that even in this article, it is called a Neutron Cannon; no laser reference that I noticed.
So this is definitely some type of neutron particle weapon, and in Charted Space would likely fall under Damper tech if introduced.
But it still does not use the "Neutron Laser" verbiage of the Warhammer 40K device.
You are right- these are tough clues to find.
From the Babylon 5 RPG (1st Ed.) - The Minbari Federation Fact Book:
Neutron Lasers: The science behind the neutron laser is only a century old, making it very contemporary by Minbari terms. While newer theoretical weapons based on tachyon streams and neutrino array are on the drawing boards of weaponsmiths on Minbar, neutron weapons are mounted on the Sharlin cruiser as a main gun and on a smaller scale as the primary cannon on the super heavy Wind Sword tank. The version of the neutron weapon mounted to ground weapons is the Neutron Assault Cannon.
From the Babylon 5 RPG (2nd Ed.) - Ship Builder's Manual:
Neutron Energy
Mastered solely by the Minbari, neutron energy is a type of fusion energy that is completely without charge – positive or negative. This means that the entire focus of the beam is to shatter the thinnest bonds of matter rather than having to steer towards one charge or the other when fired. Insanely powerful, utterly foreign to all but the most brilliant minds of the galaxy and capable of inflicting horrendous amounts of damage at very long ranges; neutron energy is the epitome of the Younger Races’ weapon technologies as far as outright damage is concerned.Once nicknamed ‘star dragon’s fire’ by the first Centauri who ever saw Minbari vessels turn their weapons on their foes, neutron weaponry is utterly unavailable to anyone except the unfathomably rich… and even then, only those who have the right contacts can actually acquire this technology. Having it might seem like a good idea, but when Minbari vessels come to collect their stolen
and
From the Babylon 5 RPG (2nd Ed.) - Ship Builder's Manual:
Neutron Energy
Improved Neutron Laser Cannon
Long, Offence 60, Beam 1d10, 2 weapon spaces
The real monster when it comes to neutron weapons, the neutron laser cannon is capable of emitting a powerful laser-like beam that will eradicate nearly any target that gets caught in its path for long. Focussing the neutron energy through alternately positive and negatively charged refracting and re-combining crystal lenses before roaring out of the huge laser emitters; each beam is capable of cutting entire sections of enemy ships off like a blade through a melon