A narrowband terahertz signal generated by a
uni-travelling carrier photodiode (UTC-PD) interfaced with a
dual-mode Fabry-Pérot laser diode is demonstrated. A beat tone
corresponding to the free spectral range is generated on the
UTC-PD, and radiated by a transverse-electromagnetic-horn
antenna. All components involved in this experiment operate at
room temperature. The terahertz signal at a frequency of 372
GHz is recorded, and the linewidth is 17 MHz. The linewidth and
the tunability of the emitted terahertz wave are analyzed, as a
function of the laser bias.