Gershenzon, E. M., Gol'tsman, G. N., & Mirskii, G. I. (1987). Submillimeter backward-wave-tube spectrometer-relaxometer. Pribory i Tekhnika Eksperimenta, 30(4), 131–137.
Abstract: A backward-wave-tube (BWT) spectrometer-relaxometer is described that is designed for study of the relaxation characteristics of photoconductors in the wavelength range of 2-0.25 mm – in particular, to measure the relaxation times of the submillimeter photoconductivity of germanium in the range of 10[sup:-4]-10[sup:-9] sec and to determine from these data the concentration of compensating impurities of from 10[sup:10] to 10[sup:14] cm[sup:-3]. The instrument uses the beats of the oscillations of two BWTs and records the amplitude-frequency response of the specimen with variation of the beat frequency from 10[sup:4] to 10[sup:8] Hz with accumulation of the desired signal for less than or equal to1 sec by means of a quadrature synchronous detector. The beat frequency is stabilized and the quadrature voltages of the synchronous detector are formed by means of phase-locked loops.
|
Gershenzon, E. M., Gol'tsman, G. N., & Semenov, A. D. (1983). Submillimeter backward wave tube spectrometer for measuring superconducting film transmission. Pribory i Tekhnika Eksperimenta, 26(5), 134–137.
Abstract: A spectrometer employing six backward wave tubes is described. It is intended for investigation of superconductors in the 0.2-3 mm range of wave lengths. During the measurement of the transmission spectrum it is possible to determine the energy gap for superconduct1ng films 50 to 4000 A thick. The transmission factor can vary from 10-1 to 10-9. Spectrum of relation of film transmission factors in superconducting and normal states is measured for determining the energy gap 2 Δ. The transmission spectrum obtained by means of a computer for vanadium film 300 A thick is given as an example. The energy gap 2 Δ = 1.4 MeV
|
Svechnikov, S., Gol'tsman, G., Voronov, B., Yagoubov, P., Cherednichenko, S., Gershenzon, E., et al. (1997). Spiral antenna NbN hot-electron bolometer mixer at submm frequencies. IEEE Trans. Appl. Supercond., 7(2), 3395–3398.
Abstract: We have studied the phonon-cooled hot-electron bolometer (HEB) as a quasioptical mixer based on a spiral antenna designed for the 0.3-1 THz frequency band and fabricated on sapphire and high resistivity silicon substrates. HEB devices were produced from superconducting 3.5-5 nm thick NbN films with a critical temperature 10-12 K and a critical current density of approximately 10/sup 7/ A/cm/sup 2/ at 4.2 K. For these devices we reached a DSB receiver noise temperature below 1500 K, a total conversion loss of L/sub t/=16 dB in the 500-700 GHz frequency range, an IF bandwidth of 3-4 GHz and an optimal LO absorbed power of /spl sime/4 /spl mu/W. We experimentally analyzed various contributions to the conversion loss and obtained an RF coupling factor of about 5 dB, internal mixer loss of 10 dB and IF mismatch of 1 dB.
|
Gol'tsman, G., Jacobsson, S., Ekstrom, H., Karasik, B., Kollberg, E., & Gershenzon, E. (1994). Slot-line tapered antenna with NbN hot electron mixer for 300-360 GHz operation. In Proc. 5th Int. Symp. Space Terahertz Technol. (pp. 209–213a).
Abstract: NbN hot-electron mixers combined with slot-line tapered antennas on Si wdnitride membranes had been fabricated. Several strips of 1 gm wide and 5 tan long made from 100 A NbN film are inserted into the slot antenna. IV-curves under local oscillator power in 300-350 GHz frequency range and conversion gain dependencies on intermediate fre- quency in the 0.1-1 GHz range are measured and compared with that for 100 GHz frequency band. Our results show that pumped IV-curves and intermediate frequency bands are different for 100 GHz and 300 GHz frequency ranges. The interpretation exploits the fact that for the lowest radiation frequency the superconducting energy gap is larger than the radiation quantum energy while they are comparable at the higher frequency. Tha results show that such mixers have good perspectives for terahertz receiving technology.
|
Gol'tsman, G. N., Semenov, A. D., Gousev, Y. P., Zorin, M. A., Gogidze, I. G., Gershenzon, E. M., et al. (1991). Sensitive picosecond NbN detector for radiation from millimetre wavelengths to visible light. Supercond. Sci. Technol., 4(9), 453–456.
Abstract: The authors report on the application of a broad-band NbN film detector which has high sensitivity and picosecond response time for detection of radiation from millimetre wavelengths to visible light. From a study of amplitude modulated radiation of backward-wave tubes and picosecond pulses from gas and solid state lasers at wavelengths between 2 mm and 0.53 mu m, they found a detectivity of 1010 W-1 cm Hz-1/2 and a response time of less than 50 ps at T=10 K. The characteristics were provided by using a 150 AA thick NbN film patterned into a structure of micron strips. According to the proposed detection mechanism, namely electron heating, they expect an intrinsic response time of approximately 20 ps at the same temperature.
|
