I don't buy it. Despite the coherency of light frequency with a laser, it still heats the atmosphere as it passes through it; i.e. it is not 100% efficient. Several thousand, if not million watts, would be needed to send a laser beam that powerful through that much atmosphere and through glass. A 50 watt laser would quickly dissipate it's energy in heat and wouldn't get very far.
Millions of watts of peak intensity is commonplace.
Its the trillions of watts that are a tricky to build.
The atmosphere doesn't absorb that much light. Sunlight is only attenuated by about half going through several miles of atmosphere.
If it did, you wouldn't be able to see mountains from 15 miles away.