|
|
Gershenzon EM, Gol'tsman GN, Elantiev AI, Karasik BS, Potoskuev SE. Intense electromagnetic radiation heating of electrons of a superconductor in the resistive state. Sov J Low Temp Phys. 1988;14(7):414–20.
|
|
|
|
Gershenzon EM, Gol'tsman GN, Gogidze IG, Gusev YP, Elantiev AI, Karasik BS, et al. Millimeter and submillimeter wave range mixer based on electronic heating of superconducting films in the resistive state. Sov Supercond. 1990;3(10):1582–97.
|
|
|
|
Karasik BS, Elantiev AI. Analysis of the noise performance of a hot-electron superconducting bolometer mixer. In: Proc. 6th Int. Symp. Space Terahertz Technol. ; 1995. p. 229–46.
Abstract: A theoretical analysis for the noise temperature of hot–electron superconducting mixer has been presented. Thecontributions of both Johnson noise and electron temperature fluctuations have been evaluated. A set of criteriaensuring low noise performance of the mixer has been stated and a simple analytic expression for the noisetemperature of the mixer device has been suggested. It has been shown that an improvement of the mixer sensitivitydoes not necessarily follow by a decrease of the bandwidth. An SSB noise temperature limit due to the intrinsic noisemechanisms has been estimated to be as low as 40–90 K for a mixer device made from Nb or NbN thin film.Furthermore, the conversion gain bandwidth can be as wide as is allowed by the intrinsic electron temperaturerelaxation time if an appropriate choice of the mixer resistance has been made. The intrinsic mixer noise bandwidthis of 3 GHz for Nb device and of 5 GHz for NbN device. An additional improvement of the theory has been madewhen a distinction between the impedance measured at high intermediate frequency (larger than the mixerbandwidth) and the mixer ohmic resistance has been taken into account.Recently obtained experimental data on Nb and NbNbolometer mixer devices are viewed in connection with thetheoretical predictions.The noise temperature limit has also been specified for the mixer device where an outdiffusion coolingmechanism rather than the electron–phonon energy relaxation determines the mixer bandwidth. A consideration ofthe noise performance of a bolometer mixer made from YBaCuO film utilizing a hot–electron effect has been done.
|
|
|
|
Wyss RA, Karasik BS, McGrath WR, Bamble B, LeDuc H. Noise and bandwidth measurements of diffusion–cooled Nb hot–electron bolometer mixers at frequencies above the superconductive energy gap. In: Proc. 10th Int. Symp. Space Terahertz Technol. Charlottesville, Virginia; 1999. p. 215–29.
|
|
|
|
Gershenson ME, Gong D, Sato T, Karasik BS, Sergeev AV. Millisecond electron-phonon relaxation in ultrathin disordered metal films at millikelvin temperatures. Appl. Phys. Lett.. 2001;79:2049–51.
|
|
|
|
Burke PJ, Schoelkopf RJ, Prober DE, Skalare A, Karasik BS, Gaidis MC, et al. Spectrum of thermal fluctuation noise in diffusion and phonon cooled hot-electron mixers. Appl Phys Lett. 1998;72(12):1516–8.
Abstract: A systematic study of the intermediate frequency noise bandwidth of Nb thin-film superconducting hot-electron bolometers is presented. We have measured the spectrum of the output noise as well as the conversion efficiency over a very broad intermediate frequency range (from 0.1 to 7.5 GHz) for devices varying in length from 0.08 μm to 3 μm. Local oscillator and rf signals from 8 to 40 GHz were used. For a device of a given length, the spectrum of the output noise and the conversion efficiency behave similarly for intermediate frequencies less than the gain bandwidth, in accordance with a simple thermal model for both the mixing and thermal fluctuation noise. For higher intermediate frequencies the conversion efficiency decreases; in contrast, the noise decreases but has a second contribution which dominates at higher frequency. The noise bandwidth is larger than the gain bandwidth, and the mixer noise is low, between 120 and 530 K (double side band).
|
|
|
|
Elant'ev AI, Karasik BS. Effect of high-frequency current on Nb superconductive film in resistive state. Sov J Low Temp Phys. 1989;15(7):379–83.
|
|
|
|
Dzardanov A, Ekstrom H, Gershenzon E, Gol'tsman G, Jacobsson S, Karasik B, et al. Hot-electron superconducting mixers for 20-500 GHz operation. In: Proc. Int. Conf. on Millimeter and Submillimeter Waves and Appl. Vol 2250.; 1994. p. 276–8.
Abstract: Bolometdcmucers based on Nb and NbN superconducting thin films in the resistive state have been prepared for 20, 100 GHz and 350-500 GHz operation. The mixing mechanism is presumably of electron heating origin. Our measurements indicate that a conversion loss of about 6-8 dB can rather easily be achieved, and that the noise is reasonably low. The requirements on the operation mode and on the film parameters in order to obtain small conversion losses or even gain are discussed. For NbN films the availability of nearly 1 GHz IF bandwidth is experimentally demonstrated. NbN hot-electron mucers combined with slot-line tapered antenna on Si membrane or with double-dipole antenna on SiO^ substrate have been fabricated. The devices we study are considered to be very promising for use in heterodyne receivers from microwaves to terahertz frequencies.
|
|
|
|
Karasik BS, Il'in KS, Ptitsina NG, Gol'tsman GN, Gershenzon EM, Pechen' EV, et al. Electron-phonon scattering rate in impure NbC films [abstract]. In: NASA/ADS.; 1998. Y35.08.
Abstract: The study of the electron-phonon interaction in thin (20 nm) NbC films with electron mean free path l=2-13 nm gives an evidence that electron scattering is significantly modified due to the interference between electron-phonon and elastic electron scattering from impurities. The interference ~T^2-term, which is proportional to the residual resistivity, dominates over the Bloch-Grüneisen contribution to resistivity at low temperatures up to 60 K. The electron energy relaxation rate is directly measured via the relaxation of hot electrons heated by modulated electromagnetic radiation. In the temperature range 1.5 – 10 K the relaxation rate shows a weak dependence on the electron mean free path and strong temperature dependence T^n with the exponent n = 2.5-3. This behaviour is well explained by the theory of the electron-phonon-impurity interference taking into account the electron coupling with transverse phonons determined from the resistivity data.
|
|
|
|
Trifonov VA, Karasik BS, Zorin MA, Gol'tsman GN, Gershenzon EM, Lindgren M, et al. 9.6 μm wavelength mixing in a patterned YBa2Cu3O7-δ thin film. In: Proc. 7th Int. Symp. Space Terahertz Technol.; 1996. p. 337–48.
Abstract: Hot-electron bolometric (HEB) mixing of 9.6 gm infrared radiation from two lasers in high-quality YBa2Cu307_3 (YBCO) patterned thin film has been demonstrated. A heterodyne measurement showed an intermediate frequency (IF) bandwidth of 18 GHz, limited by our measurement system. An intrinsic limit of 100 GHz is predicted. Between 0.1 and 1 GHz intermediate frequency, temperature fluctuations with an equivalent output noise temperature Tfl up to -150 K, contributed to the mixer noise while Johnson noise dominated above 1 GHz. The overall conversion loss at 77 K at low intermediate frequencies was measured to be -25 dB, of which 13 dB was due to the coupling loss. The IIEB mixer is very promising for use in heterodyne receivers within the whole infrared range.
|
|
