Yngvesson, K. S., Gerecht, E., Musante, C. F., Zhuang, Y., Ji, M., Goyette, T. M., et al. (1999). Low-noise HEB heterodyne receivers and focal plane arrays for the THz regime using NbN. In R. J. Hwu, & K. Wu (Eds.), Proc. SPIE (Vol. 3795, pp. 357–368). SPIE.
Abstract: We have developed prototype HEB receivers using thin film superconducting NbN devices deposited on silicon substrates. The devices are quasi-optically coupled through a silicon lens and a self-complementary log-specific toothed antenna. We measured DSB receiver noise temperatures of 500 K (13 X hf/2k) at 1.56 THz and 1,100 K (20 X hf/2k) at 2.24 THz. Noise temperatures are expected to fall further as devices and quasi-optical coupling methods are being optimized. The measured 3 dB IF conversion gain bandwidth for one device was 3 GHz, and it is estimated that the bandwidth over which the receiver noise temperature is within 3 dB of its minimum value is 6.5 GHz which is sufficient for a number of practical applications. We will discuss our latest results and give a detailed description of our prototype setup and experiments. We will also discuss our plans for developing focal plane arrays with tens of Hot Electron Bolometric mixer elements on a single silicon substrate which will make real time imaging systems in the THz region feasible.
|
Gol’tsman, G. N., & Gershenzon, E. M. (1999). Phonon-cooled hot-electron bolometric mixer: overview of recent results. Appl. Supercond., 6(10-12), 649–655.
Abstract: The paper presents an overview of recent results for NbN phonon-cooled hot electron bolometric (HEB) mixers. The noise temperature of the receivers based on both quasioptical and waveguide versions of HEB mixer has crossed the level of 1 K·GHz−1 at 430 GHz (410 K) and 600–650 GHz (480 K) and is close to this level at 820 GHz (1100 K) and 900 GHz (980 K). The gain bandwidth measured for quasioptical HEB mixer at 620 GHz reached 4 GHz and the noise temperature bandwidth was almost 8 GHz. Local oscillator power requirements are about 1 μW for mixers made by photolithography and are about 100 nW for mixers made by e-beam lithography. The studies in terahertz receivers based on HEB superconducting mixers now present a dynamic, rapidly developing field.
|
Tong, C. E., Blundell, R., Papa, D. C., Smith, M., Kawamura, J., Gol'tsman, G., et al. (1999). An all solid-state superconducting heterodyne receiver at terahertz frequencies. IEEE Microw. Guid. Wave Lett., 9(9), 366–368.
Abstract: A superconducting hot-electron bolometer mixer-receiver operating from 1 to 1.26 THz has been developed. This heterodyne receiver employs two solid-state local oscillators each consisting of a Gunn oscillator followed by two stages of varactor frequency multiplication. The measured receiver noise temperature is 1350 K at 1.035 THz and 2700 K at 1.26 THz. This receiver demonstrates that tunable solid-state local oscillators, supplying only a few micro-watts of output power, can be used in terahertz receiver applications.
|
Gerecht, E., Musante, C. F., Jian, H., Yngvesson, K. S., Dickinson, J., Waldman, J., et al. (1999). New results for NbN phonon-cooled hot electron bolometric mixers above 1 THz. IEEE Trans. Appl. Supercond., 9(2), 4217–4220.
Abstract: NbN Hot Electron Bolometric (HEB) mixers have produced promising results in terms of DSB receiver noise temperature (2800 K at 1.56 THz). The LO source for these mixers is a gas laser pumped by a CO/sub 2/ laser and the device is quasi-optically coupled through an extended hemispherical lens and a self-complementary log-periodic toothed antenna. NbN HEBs do not require submicron dimensions, can be operated comfortably at 4.2 K or higher, and require LO power of about 100-500 nW. IF noise bandwidths of 5 GHz or greater have been demonstrated. The DC bias point is also not affected by thermal radiation at 300 K. Receiver noise temperatures below 1 THz are typically 450-600 K and are expected to gradually approach these levels above 1 THz as well. NbN HEB mixers thus are rapidly approaching the type of performance required of a rugged practical receiver for astronomy and remote sensing in the THz region.
|
Yagoubov, P., Kroug, M., Merkel, H., Kollberg, E., Schubert, J., Hubers, H. - W., et al. (1999). Heterodyne measurements of a NbN superconducting hot electron mixer at terahertz frequencies. IEEE Trans. Appl. Supercond., 9(2), 3757–3760.
Abstract: The performance of a NbN based phonon-cooled Hot Electron Bolometric (HEB) quasioptical mixer is investigated in the 0.65-3.12 THz frequency range. The device is made from a 3 nm thick NbN film on high resistivity Si and integrated with a planar spiral antenna on the same substrate. The in-plane dimensions of the bolometer strip are 0.2/spl times/2 /spl mu/m. The best results of the DSB noise temperature at 1.5 GHz IF frequency obtained with one device are: 1300 K at 650 GHz, 4700 K at 2.5 THz and 10000 K at 3.12 THz. The measurements were performed at 4.5 K ambient temperature. The amount of local oscillator (LO) power absorbed in the bolometer is about 100 nW. The mixer is linear to within 1 dB compression up to the signal level 10 dB below that of the LO. The intrinsic single sideband conversion gain measured at 650 GHz is -9 dB, the total conversion gain is -14 dB.
|
Gol'tsman, G. N. (1999). Hot electron bolometric mixers: new terahertz technology. Infrared Physics & Technology, 40(3), 199–206.
Abstract: This paper presents an overview of recent results for NbN phonon-cooled hot electron bolometric (HEB) mixers. The noise temperature of the receivers based on both quasioptical and waveguide versions of HEB mixers has crossed the level of 1 K GHz−1 at 430 GHz (410 K), 600–650 GHz (480 K), 750 GHz (600 K), 810 GHz (780 K) and is close to that level at 1.1 THz (1250 K) and 2.5 THz (4500 K). The gain bandwidth measured for quasioptical HEB mixer at 620 GHz reached 4 GHz and the noise temperature bandwidth was almost 8 GHz. Local oscillator power requirements are about 1 μW for mixers made by photolithography and about 100 nW for mixers made by e-beam lithography. A waveguide version of 800 GHz receiver was installed at the Submillimeter Telescope Observatory on Mt. Graham, AZ, to conduct astronomical observations of known submillimeter lines (CO, J=7→6, CI, J=2→1). It was proved that the receiver works as a practical instrument.
|
Schubert, J., Semenov, A., Gol'tsman, G., Hübers, H. - W., Schwaab, G., Voronov, B., et al. (1999). Noise temperature and sensitivity of a NbN hot-electron mixer at frequencies from 0.7 THz to 5.2 THz. In Proc. 10th Int. Symp. Space Terahertz Technol. (pp. 190–199).
Abstract: We report on noise temperature measurements of a NbN phonon-cooled hot-electron bolometric mixer at different bias regimes. The device was a 3 nm thick bridge with in-plane dimensions of 1.7 x 0.2 gm 2 integrated in a complementary logarithmic spiral antenna. Measurements were performed at frequencies ranging from 0.7 THz up to 5.2 THz. The measured DSB noise temperatures are 1500 K (0.7 THz), 2200 K (1.4 THz), 2600 K (1.6 THz), 2900 K (2.5 THz), 4000 K (3.1 THz) 5600 K (4.3 THz) and 8800 K (5.2 THz). Two bias regimes are possible in order to achieve low noise temperatures. But only one of them yields sensitivity fluctuations close to the theoretical limit.
|
Gerecht, E., Musante, C. F., Jian, H., Zhuang, Y., Yngvesson, K. S., Dickinson, J., et al. (1999). Improved characteristics of NbN HEB mixers integrated with log-periodic antennas. In Proc. 10th Int. Symp. Space Terahertz Technol. (pp. 200–207).
|
Yagoubov, P., Kroug, M., Merkel, H., Kollberg, E., Hübers, H. - W., Schubert, J., et al. (1999). NbN hot electron bolometric mixers at frequencies between 0.7 and 3.1 THz. In Proc. 10th Int. Symp. Space Terahertz Technol. (pp. 238–246).
Abstract: The performance of NbN based phonon-cooled Hot Electron Bolometric (HEB) quasioptical mixers is investigated in the 0.7-3.1 THz frequency range. The devices are made from a 3.5-4 nm thick NbN film on high resistivity Si and integrated with a planar spiral antenna on the same substrate. The length of the bolometer microbridge is 0.1- 0.2 gm, the width is 1-2 gm. The best results of the DSB receiver noise temperature measured at 1.5 GHz intermediate frequency are: 800 K at 0.7 THz, 1100 K at 1.6 THz, 2000 K at 2.5 THz and 4200 K at 3.1 THz. The measurements were performed with a far infrared laser as the local oscillator (LO) source. The estimated LO power required is less than 500 nW at the receiver input. First results on the spiral antenna polarization measurements are reported.
|
Schubert, J., Semenov, A., Hübers, H. - W., Gol'tsman, G., Schwaab, G., Voronov, B., et al. (1999). Broad-band terahertz NbN hot-electron bolometric mixer. In Inst. Phys. Conf. (Vol. 167, pp. 663–666).
|
Yagoubov, P., Kroug, M., Merkel, H., Kollberg, E., Schubert, J., Hubers, H. - W., et al. (1998). Performance of NbN phonon-cooled hot-electron bolometric mixer at Terahertz frequencies. In Proc. 6-th Int. Conf. Terahertz Electron. (pp. 149–152).
Abstract: The performance of a NbN based phonon-cooled Hot Electron Bolometric (HEB) quasioptical mixer is investigated in the 0.65-3.12 THz frequency range. The device is made from a 3 nm thick NbN film on high resistivity Si and integrated with a planar spiral antenna on the same substrate. The in-plane dimensions of the bolometer strip are 0.2/spl times/2 /spl mu/m. The results of the DSB noire temperature are: 1300 K at 650 GHz, 4700 K at 2.5 TBz and 10000 K at 3.12 THz. The RF bandwidth of the receiver is at least 2.5 THz. The amount of LO power absorbed in the bolometer is about 100 nW. The mixer is linear to within 1 dB compression up to the signal level 10 dB below that of the LO. The intrinsic single sideband conversion gain is measured to be -9 dB, the total conversion gain -14 dB.
|
Schwaab, G. W., Auen, K., Bruendermann, E., Feinaeugle, R., Gol’tsman, G. N., Huebers, H. - W., et al. (1998). 2- to 6-THz heterodyne receiver array for the Stratospheric Observatory for Infrared Astronomy (SOFIA). In T. G. Phillips (Ed.), Proc. SPIE (Vol. 3357, pp. 85–96). SPIE.
Abstract: The Institute of Space Sensor Technology of the German Aerospace Center (DLR) is developing a heterodyne array receiver for the frequency range 2 to 6 THz for the Stratospheric Observatory for Infrared Astronomy (SOFIA). Key science issues in that frequency range are the observation of lines of atoms [e.g. (OI)], ions [e.g. (CII), (NII)], and molecules (e.g. OH, HD, CO) with high spectral resolution to study the dynamics and evolution of galactic and extragalactic objects. Long term goal is the development of an integrated array heterodyne receiver with superconducting hot electron bolometric (HEB) mixers and p-type Ge or Si lasers as local oscillators. The first generation receiver will be composed of HEB mixers in a 2 pixel 2 polarization array which will be pumped by a gas laser local oscillator. Improved Schottky diode mixers are the backup solution for the HEBs. The state of the art of HEB mixer and p-type Ge laser technology are described as well as possible improvements in the ’conventional’ optically pumped far-infrared laser and Schottky diode mixer technology. Finally, the frequency coverage of the first generation heterodyne receiver for some important astronomical transitions is discussed. The expected sensitivity is compared to line fluxes measured by the ISO satellite.
|
Svechnikov, S., Verevkin, A., Voronov, B., Menschikov, E., Gershenzon, E., & Gol'tsman, G. (1998). Quasioptical phonon-cooled NbN hot electron bolometer mixers at 0.5-1.1 THz. In Proc. 9th Int. Symp. Space Terahertz Technol. (pp. 45–51).
Abstract: The noise performance of a receiver incorporating spiral antenna coupled NbN phonon-cooled superconducting hot electron bolometric mixer is measured from 450 GHz to 1200 GHz. The mixer element is thin (thickness nm) NbN 1.5 pm wide and 0.2 i.um long film fabricated by lift-off e-beam lithography on high-resistive silicon substrate. The noise of the receiver temperature is 1000 K at 800-900 GHz, 1200 K at 950 GHz, and 1600 K at 1.08 THz. The required (absorbed) local-oscillator power is —20 nW.
|
Gousev, Y. P., Olsson, H. K., Gol'tsman, G. N., Voronov, B. M., & Gershenzon, E. M. (1998). NbN hot-electron mixer at radiation frequencies between 0.9 THz and 1.2 THz. In Proc. 9th Int. Symp. Space Terahertz Technol. (pp. 121–129).
Abstract: We report on noise temperature measurements for a NbN phonon-cooled hot-electron mixer at radiation frequencies between 0.9 THz and 1.2 THz. Radiation was coupled to the mixer, placed in a vacuum chamber of He cryostat, by means of a planar spiral antenna and a Si immersion lens. A backward-wave oscillator, tunable throughout the spectral range, delivered an output power of few 1.1W that was enough for optimum operation of the mixer. At 4.2 K ambient temperature and 1.025 THz radiation frequency, we obtained a receiver noise temperature of 1550 K despite of using a relatively noisy room-temperature amplifier at the intermediate frequency port. The noise temperature was fairly constant throughout the entire operation range and for intermediate frequencies from 1 GHz to 2 GHz.
|
Yazoubov, P., Kroug, M., Merkel, H., Kollberg, E., Gol'tsman, G., Lipatov, A., et al. (1998). Quasioptical NbN phonon-cooled hot electron bolometric mixers with low optimal local oscillator power. In Proc. 9th Int. Symp. Space Terahertz Technol. (pp. 131–140).
Abstract: In this paper, the noise perform.ance of NIN based phonon-cooled Hot Electron Bolometric (HEB) quasioptical mixers is investigated in the 0.55-1.1 THz frequency range. The best results of the DSB noise temperature are: 500 K at 640 GHz, 600 K at 750 GHz, 850 K at 910 GHz and 1250 K at 1.1 THz. The water vapor in the signal path causes a significant contribution to the measured noise temperature around 1.1 THz. The required LO power is typically about 60 nW. The frequency response of the spiral antenna+lens system is measured using a Fourier Transform Spectrometer with the HEB operating in a detector mode.
|