Lasers in the Galactic Union are electrically driven, deriving their power from fusion power plants. A laser takes roughly twice its rated power in order to fire. Most starship lasers operate in the infrared visible spectrum.
Lasers have more range than any other weapon in space combat, however, attenuation makes them ineffective at long ranges unless the target is stationary. Common laser engagement range is under 5 light seconds, usually 1.
They are quite effective against shields, but only reach power levels of 50 to 100 gigawatts owing the difficulty in producing lasing crystals of the size and cost required for large lasers.
The are also the most versatile weapon in space combat and are used for both offense and defense. Some lasers are capable of dual use, allowing attacks against other warships and using beam-splitters to generate multiple lower powered beams for anti-missile point defense. They can also be configured with special mirrors to help with hull repairs.
Laser power is expressed in output, with the operating power requirement approximately twice the output rating.
Lasers fail for a number of reasons. For example, nearby nuclear detonations can disrupt their delicate electronics or HE missile shrapnel can damage complicated mirrors and emitter housings.
Still, their versatility means that nearly every warship carries at least some. Many systems often require merchant vessels to be unarmed, Nevertheless, lasers are so ubiquitous that many of the systems will look the other way.