Harmonic mixing and the heterodyne detection of laser radiation

An experiment is described in which prime and irreducible multiples of fundamental frequencies near 70 GHz are mixed with radiation from a carcinotron at 300 GHz. Forty-seven orders of mixing were observed. From the recent successful mixing of 75 GHz with radiation of a CN laser at 964 GHz, it is argued that in the above experiment 3300 GHz were actually present in the mixer.