Mixing of 10-microm radiation in room-temperature Schottky diodes.

Schottky diodes have been used as room-temperature mixers of CO(2)-laser radiation. When a microwave local oscillator signal was introduced directly into the diode, beat notes between lasers separated by up to 69 GHz were observed. At CO(2) frequencies (30 THz) the photon energy exceeds the measured dc nonlinearities, and the device is expected to approach operation as a photon counter rather than a classical resistive mixer.

Submillimeter heterodyne detection of interstellar carbon monoxide at 434 micrometers.

A submillimeter heterodyne radiometer, developed for astronomical applications, uses an optically pumped laser local oscillator and a quasi-optical Schottky diode mixer. The resultant telescope-mounted system, which has a noise temperature less than 4000 K (double sideband) and high frequency and spatial resolution, has been used to detect the J = 6 --> 5 rotational transition of carbon monoxide at 434 micrometers in the Orion molecular cloud. The measurements, when compared with previous millimeter-wave data, indicate that the broad carbon monoxide emission feature is produced by an optically thin gas whose temperature exceeds 180 K.

Stimulated Brillouin and Raman Scattering in Quartz at 2.1{degrees} to 293{degrees} Kelvin.

Stimulated Brillouin shifts observed at 2.1 degrees K in quartz are the same as those observed at 293 degrees K. No extreme nonlinear behavior is observed.