The Mega Laser Station was a simple idea, a laser of super-capital size, enclosed in its own station, to be used as a massive deterrent, an anti-ship one shot weapon, and a weapon of space to surface bombardment. A number of these stations were drawn up, and several even went into mock up and conceptual development, but were ultimately abandoned. The power of the mega laser was ultimately one of the flaws that brought it down.
The Failure of the Mega Laser
The Mega Laser was hounded by problems and flaws from the very beginning. The most pressing issue was that the station required to house any of the mega laser prototypes was going to be large. This massive size meant aiming the laser was slow and problematic. Shooting at great range required exceptional accuracy which also was lacking in the station based targeting system. Most targeting models demonstrated that the mega laser was only capable of hitting targets on earth, the moon, or large objects like asteroids and stations. Most things with even modest propulsion could perform evasive maneuvers and avoid the mega laser beam. To function in an anti-ship role, the mega laser had to be within short range (in space terms, no more than a few hundred miles).
The limited combat effective range of the mega laser prototypes left them vulnerable to counter attack by the ships they targeted, and being stations themselves, proved easy targets for counter strike. Most modeled battles between mega laser installations and space task forces saw the destruction of the mega laser in almost 98% of simulations. The laser could destroy a ship or two, but the speed and numbers of smaller ships like frigates and destroyers allowed for the flanking and destruction of the mega laser. The answer was to fully arm and armor the mega laser and turn it from a super weapon into a 'death star' type battle station. Existing battle stations had proved of limited effectiveness, and were drainingly expensive in terms of resources, manpower, and financial support.
The death blow to the Mega Laser came from its power itself. Various plans and projects were leaked to the public and there was a massive outcry against the waste of resources on super space lasers. The trifecta of high cost, low tactical and strategic value, and public outcry doomed the idea. Not long after this, the Mega Laser projects were abandoned.
Sample Mega Laser Systems
The Eurasian Alliance Kresnik-99 system was considered one of the most primitive. It consisted of ten heavy naval laser systems being mated together and firing through a single custom built emitter. The higher output of the system allowed it to produce an impressive amount of laser power, but the cooling systems required to keep it cool were extensive and prone to failure. Redundant cooling systems account for as much mass within the system as the power generation. Three Kresniks were constructed, two failed in firing tests, melting down in various stages. The third was placed in storage and been used as a source of parts for the warships the Alliance has that are equipped with the same heavy naval laser used to built the Kresnik.
The Federation Sunbeam system used a dozen photon generators and a mile long focusing emitter to produce a massive shaft of intense light. The beam lacked penetrating power, but could blind sensors, and overheat the targets cooling systems. The use of photon generators proved a viable option, but the follow up plans for a more effective Sunbeam system would require many more photon generators, more powerplants, and larger solar collectors. The project was abandoned, and the half scale Sunbeam generator ship was the Maw Installation.
Other nations attempted to plan their own mega lasers, but were far behind the other powers. When the Kresniks and Sunbeam were revealed as failures, these plans and models were canceled.
The Mega Laser systems are space born super weapons and follow the basic tropes.
Surprise! Mega Laser - A nation has built a mega laser, and it is up to the PCs to locate it, and destroy it before it falls to the fleet to hunt it down and for hundreds of people to die in the process, or to eliminate the station before it reaches firing position to burn a city off of the Earth.
Terrorist Special - a terrorist faction or rogue nation has built a mega laser, even a half scale mega laser and is using it to hold the world hostage. One finger on the firing button they make demands and scream that if they see so much as a shuttle approaching them they start potshotting the planet. The PCs are brought in as specialists.
Hijackers - the PCs are sent to recover a previously unknown mega space laser. They have a secret mission, a massive recovery ship to help, and they have to tiptoe into enemy space, steal something from them, and leave before they realize its gone.
Anti-Super Weapon - there is another super weapon being deployed, threatening to destroy the earth, or the moon, and the PCs have the job to return with a decommissioned mega space laser, and use it to destroy the other super weapon. I see you have an impressive doomsday device, let me show you mine (pulls out space station sized laser cannon) PEW PEW