|
|
Hajenius, M., Baselmans, J. J. A., Baryshev, A., Gao, J. R., Klapwijk, T. M., Kooi, J. W., et al. (2006). Full characterization and analysis of a terahertz heterodyne receiver based on a NbN hot electron bolometer. J. Appl. Phys., 100(7), 074507.
|
|
|
|
Khosropanah, P., Gao, J. R., Laauwen, W. M., Hajenius, M., & Klapwijk, T. M. (2007). Low noise NbN hot electron bolometer mixer at 4.3 THz. Appl. Phys. Lett., 91, 221111 (1 to 3).
Abstract: We have studied the sensitivity of a superconducting NbN hot electron bolometer mixer integrated with a spiral antenna at 4.3 THz. Using hot/cold blackbody loads and a beam splitter all in vacuum, we measured a double sideband receiver noise temperature of 1300 K at the optimum local oscillator (LO) power of 330 nW, which is about 12 times the quantum noise (hnu/2kB). Our result indicates that there is no sign of degradation of the mixing process at the superterahertz frequencies. Moreover, a measurement method is introduced which allows us for an accurate determination of the sensitivity despite LO power fluctuations.
|
|
|
|
Ganzevles, W. F. M., Gao, J. R., de Korte, P. A. J., & Klapwijk, T. M. (2001). Direct response of microstrip line coupled Nb THz hot-electron bolometer mixers. Appl. Phys. Lett., 79(15), 2483–2485.
|
|
|
|
Jackson, B. D., Baryshev, A. M., de Lange, G., Gao, J. R., Shitov, S. V., Iosad, N. N., et al. (2001). Low-noise 1 THz superconductor-insulator-superconductor mixer incorporating a NbTiN/SiO2/Al tuning circuit. Appl. Phys. Lett., 79(3), 436.
|
|
|
|
Baselmans, J. J. A., Hajenius, M., Gao, J. R., Klapwijk, T. M., de Korte, P. A. J., Voronov, B., et al. (2004). Doubling of sensitivity and bandwidth in phonon cooled hot electron bolometer mixers. Appl. Phys. Lett., 84(11), 1958–1960.
Abstract: We demonstrate that the performance of NbN lattice cooled hot electron bolometer mixers depends strongly on the interface quality between the bolometer and the contact structure. We show experimentally that both the receiver noise temperature and the gain bandwidth can be improved by more than a factor of 2 by cleaning the interface and adding an additional superconducting interlayer to the contact pad. Using this we obtain a double sideband receiver noise temperature TN,DSB=950 K
at 2.5 THz and 4.3 K, uncorrected for losses in the optics. At the same bias point, we obtain an IF gain bandwidth of 6 GHz.
|
|
