Frequency measurement at 4.25 THz (70.5μm) using a Josephson harmonic mixer and phase-lock techniques

Abstract

A direct frequency measurement has been made on the 70.5 mu m wavelength line of the methyl alcohol optically-pumped laser by 43rd-harmonic mixing with a klystron using a point-contact Josephson junction. It was possible to phase-lock the klystron to the laser. The centre frequency of the emitted radiation when the CO2 pump laser (9.68 mu m, P(34)) was tuned near the absorption line centre was found to be 4251 674.0+or-0.7 MHz. This result is about 5 MHz higher than an earlier published result by Petersen et al. (1975). A result is also given for the frequency of the 118-8 mu m wavelength line in methyl alcohol.