Detection and conversion of microwave and millimeter-range electromagnetic signals by quasi-one-dimensional NbSe3 crystals

An examination of the nonlinear properties of quasi-one-dimensional NbSe3 crystals in the millimeter wavelength range is discussed. Electromagnetic signals have been detected by using the crystals over a temperature range of 77-300 K. NbSe3 whiskers 5-10 microns in diameter and approximately 5 mm long were studied in the frequency range 25-70 GHz. Voltage-power characteristics were measured to determine the sensitivity of the samples to EM radiation supplied by Si IMPATT diodes delivering pulsed power on the order of 1 micro- to 1 picoW. Sensitivity varied little over the 77-300 C temperature range. Tests were also run using the whiskers as mixers at 35 and 57 GHz. Conversion losses were reduced by increasing the power level of the heterodyne oscillator or lowering the temperature. The NbSe crystals were concluded to be satisfactory candidates for uses as detectors and mixers for millimeter waves.