SPECTROSCOPY OF THE HARMONICS OF SUBMILLIMETER BACKWARD-WAVE OSCILLATORS

The harmonics content in the radiation generated by a submillimeter ba ckward wave oscillator is described for the first time. Lines were obs erved in the second and third harmonic using an acoustic cell as a rec eiver in the 600-GHz frequency range. A possible explanation is given for the harmonic generation. It is thought that strong enough electron bunching induces nonsinusoidal convection currents in slow-wave syste ms. This is analogous to frequency multiplication in centimeter-wave k lystrons. Possible means for reaching higher frequencies using more se nsitive receivers such as cryogenic bolometers and changing constructi on and/or operational regimes of oscillators are pointed out. (C) 1995 Academic Press, Inc.