Superlaser

A superlaser is broadly defined as being a laser based device of such immense power that the energy being transferred is equal to visible quantities of mass. One metric use to define a superlaser is a laser that transfers the same amount of energy per second as is contained in 1 gram of mass-energy. In other words, the amount of energy delivered to a target by the laser in one second is equivalent to the energy released if you annihilated 1 g of matter on that target.

Thus, the amount of energy transferred by a superlaser is immense, with effects often dwarfing those of nuclear explosives. Such power can be used to various ends.

Use as a weapon
One of the most obvious uses of superlasers is as a weapon. The enormous amount of energy transferred dwarfs any nuclear weapon. Disadvantages of such a weapon include it's nature as a fixed beam (that can be shielded against and/or easily avoided) it's subluminal speed and the immense amount of energy required to generate a superlaser beam.

One invaluable usage of superlasers is as a defence against asteroids and comets, them being some of the only devices with sufficient energy to completely destroy an incoming astronomical object.

Use in mining
The immense energy from superlasers can be used to melt small astronomical objects like asteroids, and to extract the minerals contained therein.