New Frequency Measurements and Techniques in the 30-THz Region

It is proposed that the frequency differences between CO2 laser ines and the harmonics of these differences might be used as intermediate frequencies to bridge the gap between microwave frequency standards and infrared frequencies to simplify absolute measurements of the latter. Tungsten-nickel point-contact diodes would be used as harmonic generators and mixers. The preliminary results of an experimental feasibility study are presented. A description of a novel two-frequency laser, built for this study, is given. It is shown that beat frequencies between differences up to 715 GHz and microwave frequency harmonics up to the twelfth can be observed; interactions with at least the third harmonic of a CO2 frequency difference are possible, producing signals with an S/N of 51 dB in a 2.2-s time constant receiver; attempts to observe a beat between a CO2 frequency and the seventh harmonic of a difference were not successful.