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Author González, F. J.; Boreman, G. D. openurl 
  Title Comparison of dipole, bowtie, spiral and log-periodic IR antennas Type Journal Article
  Year 2005 Publication (up) Infrared Physics & Technology Abbreviated Journal Inf Phys & Technol  
  Volume 46 Issue 5 Pages 418-428  
  Keywords optical antennas; Microbolometer; Infrared antennas; Antenna efficiency; Antenna-coupled detectors  
  Abstract Antenna-coupled microbolometers use planar lithographic antennas to couple infrared radiation into a bolometer with sub-micron dimensions. In this paper four different types of infrared antennas were fabricated on thin grounded-substrates and coupled to microbolometers. Dipole, bowtie, spiral and log-periodic IR antenna-coupled detectors were measured at 10.6 μm and their performance compared. A new method to calculate the radiation efficiency based on the spatial and angular response of infrared antennas is presented and used to evaluate their performance. The calculated radiation efficiency for the dipole, bowtie, spiral and log-periodic IR antennas was 20%, 37%, 25% and 46% respectively. A dipole-length study was performed and shows that the quasistatic value of the effective permittivity accurately describes the incident wavelength in the substrate at infrared frequencies for antennas on a thin substrate.  
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  Notes Approved no  
  Call Number RPLAB @ gujma @ Serial 739  
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Author Lobanov, Y. V.; Vakhtomin, Y. B.; Pentin, I. V.; Rosental, V. A.; Smirnov, K. V.; Goltsman, G. N.; Volkov, O. Y.; Dyuzhikov, I. N.; Galiev, R. R.; Ponomarev, D. S.; Khabibullin, R. A. url  doi
openurl 
  Title Time-resolved measurements of light–current characteristic and mode competition in pulsed THz quantum cascade laser Type Journal Article
  Year 2021 Publication (up) Optical Engineering Abbreviated Journal Optical Engineering  
  Volume 60 Issue 8 Pages 1-8  
  Keywords HEB, terahertz pulse generation, terahertz pulse detection, QCL, quantum cascade laser, superconducting hot electron bolometer  
  Abstract Quantum cascade lasers (QCL) are widely adopted as prominent and easy-to-use solid-state sources of terahertz radiation. Yet some applications require generation and detection of very sharp and narrow terahertz-range pulses with a specific spectral composition. We have studied time-resolved light-current (L–I) characteristics of multimode THz QCL operated with a fast ramp of the injection current. Detection of THz pulses was carried out using an NbN superconducting hot-electron bolometer with the time constant of the order of 1 ns while the laser bias current was swept during a single driving pulse. A nonmonotonic behavior of the L–I characteristic with several visually separated subpeaks was found. This behavior is associated with the mode competition in THz QCL cavity, which we confirm by L–I measurements with use of an external Fabry–Perot interferometer for a discrete mode selection. We also have demonstrated the possibility to control the L–I shape with suppression of one of the subpeaks by simply adjusting the off-axis parabolic mirror for optimal optical alignment for one of the laser modes. The developed technique paves the way for rapid characterization of pulsed THz QCLs for further studies of the possibilities of using this approach in remote sensing.  
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  Publisher Spie Place of Publication Editor  
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  Notes Approved no  
  Call Number 10.1117/1.Oe.60.8.082019 Serial 1260  
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Author Irwin, K.D. openurl 
  Title Thermodynamics of nonlinear bolometers near equilibrium Type Conference Article
  Year 2006 Publication (up) Proc. 11th International Workshop on Low Temp. Detectors Abbreviated Journal Proc. 11th International Workshop on Low Temp. Detectors  
  Volume 559 Issue 2 Pages 718-720  
  Keywords bolometers, microcalorimeters, nonlinear thermodynamics, nonequilibrium  
  Abstract We present the first thermodynamically correct calculation of the noise in a simple nonlinear resistive bolometer or calorimeter operated out of equilibrium. The solution is rigorous only for first- and second-order deviations from equilibrium, and for the linear and quadratic terms of dissipative elements. In contrast, existing models of noise in resistive bolometers are based on the application of equilibrium theories to a system that is often nonlinear and out of equilibrium. We derive solutions applicable both in and out of steady state. The noise has power spectral density different from the equilibrium theory, and it has higher-order correlations and non-Gaussian characteristics. The results do not apply to non-Markovian hidden variables in the bolometer.  
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  Notes Recommended by Klapwijk Approved no  
  Call Number Serial 915  
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Author Tovpeko, N. A.; Trifonov, A. V.; Semenov, A. V.; Antipov, S. V.; Kaurova, N. S.; Titova, N. A.; Goltsman, G. N. url  openurl
  Title Bandwidth performance of a THz normal metal TiN bolometer-mixer Type Conference Article
  Year 2019 Publication (up) Proc. 30th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 30th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 102-103  
  Keywords TiN normal metal bolometer, NMB  
  Abstract We report on the bandwidth performance of the normal metal TiN bolometer-mixer on top of an Al 2 O 3 substrate, which is capable to operate in a wide range of bath temperatures from 77 K – 300 K. The choice of the combination TiN / Al 2 O 3 is related to an advanced heat transport between the film and the substrate in this pair and the sufficient temperature coefficient of resistance. The data were taken at 132.5 – 145.5 GHz with two BWOs as a signal and an LO source. Measurements were taken on TiN films of different thickness starting from 20 nm down to 5 nm coupled into a spiral Au antenna, which improves matching of incoming radiation with the thin TiN fim. Our experiments demonstrate effective heat coupling from a TiN thin film to an Al 2 O 3 substrate (111) boosting gain bandwidth (GB) of TiN bolometer up to 6 GHz for 5 nm thin film. Current results indicate weak temperature dependence of GB on the bath temperature of the TiN bolometer. Theoretical estimations of GB performance meet with experimental data for 5 nm thin TiN films.  
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  Notes Approved no  
  Call Number Serial 1279  
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Author Ryabchun, S.; Tong, C.-yu E.; Blundell, R.; Kimberk, R.; Gol’tsman, G. url  doi
openurl 
  Title Effect of microwave radiation on the stability of terahertz hot-electron bolometer mixers Type Conference Article
  Year 2006 Publication (up) Proc. SPIE Abbreviated Journal Proc. SPIE  
  Volume 6373 Issue Pages 63730J (1 to 5)  
  Keywords NbN HEB mixers, hot-electron bolometer mixers, stability, Allan variance, LO power fluctuations  
  Abstract We report our studies of the effect of microwave radiation, with a frequency much lower than that corresponding to the energy gap of the superconductor, on the performance of the NbN hot-electron bolometer (HEB) mixer incorporated into a THz heterodyne receiver. It is shown that exposing the HEB mixer to microwave radiation does not result in a significant rise of the receiver noise temperature and degradation of the mixer conversion gain so long as the level of microwave power is small compared to the local oscillator drive. Hence the injection of a small, but controlled amount of microwave radiation enables active compensation of local oscillator power and coupling fluctuations which can significantly degrade the stability of HEB mixer receivers.  
  Address  
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  Publisher SPIE Place of Publication Editor Anwar, M.; DeMaria, A.J.; Shur, M.S.  
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  ISSN ISBN Medium  
  Area Expedition Conference Terahertz Physics, Devices, and Systems  
  Notes Approved no  
  Call Number Serial 1441  
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