The University of Washington in Seattle has introduced a system that makes it possible to charge smartphones and other devices using a laser. With this purpose in mind, the scientists working with professors Shyam Gollokota and Arka Majumdar attached a 5 x 5 cm photovoltaic energy cell to the back of a telephone. A laser, which is currently capable of covering a distance of roughly 4.3 meters, is then aimed at this cell. However, according to the developers, the system can be expanded so that the laser beam would be able to hit a surface of 100 cm² from a distance of 12 meters.
In order to prevent injuries, the laser is surrounded by four light curtains, whose beams are shone back by small reflectors created by a 3D printer and switch off the machine immediately if they are interrupted. According to the paper that the scientists published regarding their development, this shutdown takes place so quickly that it is impossible for people to be struck by the laser beam.
There is a continuous power transfer of 2 watts, which means the wireless laser-charger can charge a telephone just as quickly as a USB cable. However, there are some doubts about this data: There are Qi chargers already available, which charge smartphones using induction energy and work with a standard output of 5 watts, yet require a significantly longer charging period.