The Study of Harmonic-Mode Operation of GaAs TUNNETT Diodes and InP Gunn Devices Using a Versatile Terahertz Interferometer

A simple Fourier transform terahertz spectrometer was constructed to evaluate the transmission and reflection spectra of materials as well as the emission spectra of pulsed broadband and continuous-wave narrowband sources. It works as a Michelson interferometer without a beam splitter and operates at room temperature with a Golay cell as the detector. This interferometer was em- ployed to study the extraction of power from GaAs 'TUNNETT diodes and InP Gunn devices at the second or higher harmonic frequency above 325 GHz. As ini- tial, results, output power levels of more than 80 p.W were generated with a GaAs TUNNETT diode at 355 GHz in a third-harmonic mode, more than 0.6 mW at 328 GHz, with an InP Gunn device in a second- harmonic mode, and more than 5 (tW at 415 GHz, with an InP Gunn device in a third-harmonic mode.