The third tier does okay damage and can compete with other weapons without outshining them. I think that's good because the weapon is unique and doesn't spend ammo. It's still a bit weak but I'd rather suggest increasing its rate of fire, which I explain lower down.
But the lower tiers are incredibly weak. Especially considering how expensive the weapon is, I think it calls for a LOT more damage. The tier 3 base damage of 60 makes sense. But I would increase tier 1 to 30 and tier 2 to 45. That matches their energy cost (tier 1 costing exactly half the energy of tier 3) and makes it deal enough damage to be worth using.
Still, even with all that damage, it's useless without a lot of laser turret upgrades and still not that strong with them. It's also very easy to keep it charged with only one or two chargers, and there's very little reason to have more than that, even with several firing speed upgrades. I would suggest raising its base firing speed from 2/s to 3/s. This will make it drain its charge much more quickly and will also make it a good weapon if fired sparingly, or if you dedicate several armor slots to chargers. I can even see a basis for reducing the charge rate. One charger is still fine if you don't fire often, because the weapon stores enough charge for quite a few shots. It should deplete gradually while being fired unless you have a lot of chargers.