  Since the days of Hertz, radio transmitters have evolved from rudimentary
circuits emitting around 50 MHz to modern ubiquitous Wi-Fi devices operating at
gigahertz radio bands. As wireless data traffic continues to increase there is
a need for new communication technologies capable of high-frequency operation
for high-speed data transfer. Here we give a proof of concept of a new compact
radio frequency transmitter based on a semiconductor laser frequency comb. In
this laser, the beating among the coherent modes oscillating inside the cavity
generates a radio frequency current, which couples to the electrodes of the
device. We show that redesigning the top contact of the laser allows one to
exploit the internal oscillatory current to drive an integrated dipole antenna,
which radiates into free space. In addition, direct modulation of the laser
current permits encoding a signal in the radiated radio frequency carrier.
Working in the opposite direction, the antenna can receive an external radio
frequency signal, couple it to the active region and injection lock the laser.
These results pave the way to new applications and functionality in optical
frequency combs, such as wireless radio communication and wireless
synchronization to a reference source.
