Lasers through air gives straight line communication that is much faster than traditional fiber optic networks. In the future the biggest competitor to lasers through air will likely be hollow core fiber.
Advantage: Speed limit about 0.997c. That is considerably faster than todays optical fiber cables. Realtively easy to make stright lines. Still need permits to set up towers, laser senders/recivers.
Disadvantage: possibly affected by weather conditions. The technology has been improved to get around weather conditions, but rain + fog is possibly not a good scenario.
Informative youtube about laser communication technology that is used in high speed trading.
2015 (ZeroHedge blog) Meanwhile, Over At The "New York" Stock Exchange... Lasers
2014 New laser network between NYSE and NASDAQ will allow high-frequency traders to make even more money
2014 (WSJ): High-Speed Stock Traders Turn to Laser Beams "As high-speed stock traders push to trade ever faster, their newest move involves harnessing a technology that U.S. military jets use to communicate as they soar across the sky: lasers."
2014 Laser Beams Speed Financial Trading When it comes to the financial arms race, or the race to zero latency, traditional data feeds aren’t fast enough. The need for speed has ushered in a new breed of blisteringly fast communication systems, and the latest weapon of choice is the laser.
2013 (BBC) Financial traders turn to lasers for faster deals
Company involved in lasers through air: Anova Technologies (I have no relationship to this firm, but found their website quite informative.)