OPERATION OF THE GRATING-COUPLED OSCILLATOR AT SUBMILLIMETER FAR-INFRARED WAVELENGTHS

Grating-coupled oscillator experiments covering the 1 cm-400-mu-m wavelength range are reported. Two coexisting modes of operation have been identified; a relatively low frequency signal (LFM) that is widely tunable with voltage and a high frequency signal (HFM) that tunes over a more reduced wavelength and voltage range. Observed wavelength and start oscillation currents of the LFM correspond well with a simple model of the beam-electromagnetic wave interaction. Electronic tuning ranges of 50 GHz with start oscillation currents of 0.5-1.5 A at beam voltages of 50-100 kV are typical. Power levels approach a kW at longer millimeter wavelengths.