Search

Experimental results of harmonic generation in the submillimetric wavelength region using carcinotrons as fundamental sources are reported. The multiplier is a commercial cross-waveguide structure equipped with a Schottky barrier diode operating as a non-linear resistance. Power levels useful for many spectroscopic applications can be obtained with these wideband tunable sources.

Some experimental results of video detection in the submillimeter range with Schottky-barrier diodes are reported in the first part of this note and different mounts are compared. The dependence of video responsivity on the frequency for the devices examined seems to obey more likely an ƒ −4 law than the theoretically expected ƒ −2 . The second part concerns harmonic multiplication with Schottky diodes; experimental results are reported for 100 GHz multiplication up to the 6th harmonic.

In this paper the problem of phase stabilization of submillimetric backward wave oscillators (BWO's) is considered. Experimental results are given about the phase-lock of a 600 GHz BWO to a quartz crystal reference, via a frequency multiplier chain of high phase spectral purity. The spectral analysis of the locked BWO is performed both on the IF and on the submillimetric output signal.

A direct frequency measurement of the 496 μm, K = 2 line from a CH 3 F laser is reported. Our laser is a metallic wave-guide device pumped by a frequency stabilized CO 2 laser; its output is mixed in a CaAs-Au Schottky barrier diode with a 100 GHz klystron and the beat note is observed on a spectrum analyzer. The result is f CH 3 F (496 μm, K = 2) = 604 297.5 ± 0.2 MHz.

We report the absolute frequency measurement of the 81.5 μm rotational transition and of the 263.4 μm inversion transition in the ν2 vibrational state of 14NH3. A very low-phase noise frequency multiplication chain has been used in the experiments allowing a phase-coherent synthesis up to the frequency of 3.7 THz.