Wi-Fi and cellular data traffic are increasing exponentially but, unless the capacity of wireless links can be increased, all that traffic is bound to lead to unacceptable bottlenecks.
Upcoming 5G networks are a temporary fix and there is already talk of 6G. For a long term solution, esearchers have focused on terahertz frequencies, the submillimeter wavelengths of the electromagnetic spectrum. Data traveling at terahertz frequencies could move hundreds of times faster than today's wireless.
"This work represents a complete paradigm shift for the way a laser can be operated," said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering and senior author of the paper. "This new phenomenon transforms a laser – a device operating at optical frequencies – into an advanced modulator at microwave frequencies, which has a technological significance for efficient use of bandwidth in communication systems."
Frequency combs are widely-used, high-precision tools for measuring and detecting different frequencies of light. Unlike conventional lasers, which emit a single frequency, these lasers emit multiple frequencies simultaneously, evenly spaced to resemble the teeth of a comb. Currently, optical frequency combs are used for everything from measuring the fingerprints of specific molecules to detecting distant exoplanets.
This research, however, wasn't interested in the optical output of the laser.