Harvard Researchers Construct the First Successful Laser Radio Transmitter

Virtually all wireless data communication today relies on radio signals. Those signals have a traditional sine wave that is characterized by frequency and amplitude. Frequency is the number of wave cycles per second, and amplitude is half of the distance between opposing peaks. Either of those can be modulated to carry data — FM on your car radio is frequency-modulated, and AM is amplitude-modulated. How much data can be carried depends on the frequency of the wave, which is why researchers from Harvard have developed the first ever laser radio transmitter.

It’s important to understand that this isn’t using the laser itself to carry data, which is an existing technology that relies on line-of-sight, and the same basic idea behind fiber optics. Instead, an infrared frequency comb in a quantum cascade laser is used to generate microwave radiation. That can be then be modulated to carry data, just like any other wave. Microwave radiation has a sub-millimeter wavelength, and frequencies in the terahertz range. For reference, your home WiFi router most likely operates in either the 2.4 GHz or 5 GHz range.

What that means is that a theoretical WiFi system using the laser radio transmission technology would be able to send data hundreds of times faster than our current technology can. In their tests, the researchers also demonstrated that the same prototype device could be used to receive those microwave signals. That brings the technology one step closer to be practical. The researchers are, however, quick to point out that it will be a long time before this will be ready for the commercial market. But, it’s still a major breakthrough on the way to ultra-fast wireless data transmission.