Yes. See http://starwars.wikia.com/wiki/Lightsaber#Mechanics_and_specifications
Cliff notes version as requested by commenter:
A diatium power cell generates the energy which passes through a series of focusing lenses and energizers before being converted into plasma. Focusing crystals project the plasma. Some widgets made the beam coherent. Plasma was reflected back by blade containment field. Insert other pseudo-technical mumbo jumbo to taste.
Full explanation from Wookiepedia:
High levels of energy generated by a high-output Diatium power cell was unleashed through a series of focusing lenses and energizers that converted the energy into plasma. The plasma was projected through a set of focusing crystals that lent the blade its properties and allowed for the adjustment of blade length and power output. The ideal number of crystals was three, though only one was required.
Once focused by the crystals, the plasma was sent through a series of field energizers and modulation circuitry within the emitter matrix that further focused it, making it into a coherent beam of energy that was projected from the emitter. The blade typically extended about a meter before being arced by the blade containment field back to a negatively charged fissure ringing the emitter, where it was channeled back to the power cell by a superconductor, completing the circuit.
Below is a list of the primary parts almost all lightsabers needed to use to function properly:
Diatium power cell
Inert power insulator