| Records |
| Author |
Hajenius, M.; Baselmans, J. J. A.; Gao, J. R.; Klapwijk, T. M.; de Korte 2, P. A. J.; Voronov, B.; Gol’tsman, G. |
| Title |
Increased bandwidth of NbN phonon cooled hot electron bolometer mixers |
Type |
Conference Article |
| Year |
2004 |
Publication |
Proc. 15th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 15th Int. Symp. Space Terahertz Technol. |
| Volume |
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Issue |
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Pages |
381-386 |
Keywords  |
NbN HEB mixers, IF bandwidth |
| Abstract |
We study experimentally the IF gain bandwidth of NbN phonon-cooled hot-electron-bolometer (HEB) mixers for a set of devices with different contact structures but an identical NbN film. We observe that the IF bandwidth depends strongly on the exact contact structure and find an IF gain bandwidth of 6 GHz for a device with an additional superconducting layer (NbTiN) in between the active NbN film and the gold contact to the antenna. These results contradict the common opinion that the IF bandwidth is determined by the phonon-escape time between the NbN film and the substrate. Hence we calculate the IF gain bandwidth of a superconducting film using a two-temperature model. We find that the bandwidth increases strongly with operating temperature and is not limited by the phonon escape time. This is because of strong temperature dependence of the phonon specific heat in the NbN film. |
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1494 |
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Ryabchun, S.; Tong, C.-yu E.; Blundell, R.; Kimberk, R.; Gol’tsman, G. |
| Title |
Effect of microwave radiation on the stability of terahertz hot-electron bolometer mixers |
Type |
Conference Article |
| Year |
2006 |
Publication |
Proc. SPIE |
Abbreviated Journal |
Proc. SPIE |
| Volume |
6373 |
Issue |
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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. |
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SPIE |
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Anwar, M.; DeMaria, A.J.; Shur, M.S. |
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Terahertz Physics, Devices, and Systems |
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1441 |
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Semenov, A.; Richter, H.; Smirnov, A.; Günther, B.; Hübers, H.-W.; Il’in, K.; Siegel, M.; Gol’tsman, G.; Drakinskiy, V.; Merkel, H.; Karamarkovic, J. |
| Title |
Development of HEB mixers for GREAT and for security screening |
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Abstract |
| Year |
2007 |
Publication |
Proc. 18th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 18th Int. Symp. Space Terahertz Technol. |
| Volume |
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Pages |
184 |
| Keywords |
NbN HEB mixers, GREAT |
| Abstract |
We report the study on the quasioptical coupling efficiency and the gain bandwidth of NbN hot-electron bolometer mixers developed for the 4.7 THz channel of the German receiver for Astronomy at THz-frequencies (GREAT) and for security screening at subterahertz frequencies. Radiation coupling efficiency and directive properties of integrated lens antennas with log-spiral, log-periodic and double-slot planar feeds coupled to a hot-electron bolometer were experimentally studied at frequencies from 1 THz to 6 THz and compared with simulations based on the method of moments and the physical-optics ray tracing. For all studied antennas the modeled spectral dependence of the coupling efficiency fits to the experimental data obtained with both Fourier transform spectroscopy and noise temperature measurements only if the complex impedance of the bolometer is explicitly taken into account. Our experimental data did not indicate any noticeable contribution of the quantum noise to the system noise temperature. The experimentally observed deviation of the beam pattern from the model prediction increases with frequency and is most likely due to a non- ideality of the presently used lenses. Study of the intermediate frequency mixer gain at local oscillator (LO) frequencies between 2.5 THz and 0.3 THz showed an increase of the gain bandwidth at low LO frequencies that was understood as the contribution of the direct interaction of magnetic vortices with the radiation field. We have found that the non- homogeneous hot-spot model more adequately describes variation of the intermediate frequency bandwidth with the applied local oscillator power than any of uniform mixer models. The state-of-the-day performance of the GREAT 4.7-THz channel and the 0.8-THz security scanner will be presented. |
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1420 |
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| Author |
Antipov, S.; Trifonov, A.; Krause, S.; Meledin, D.; Desmaris, V.; Belitsky, V.; Gol’tsman, G. |
| Title |
Gain bandwidth of NbN HEB mixers on GaN buffer layer operating at 2 THz local oscillator frequency |
Type |
Conference Article |
| Year |
2017 |
Publication |
Proc. 28th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 28th Int. Symp. Space Terahertz Technol. |
| Volume |
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Issue |
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Pages |
147-148 |
| Keywords |
NbN HEB mixers, GaN buffer-layer, IF bandwidth |
| Abstract |
In this paper, we present IF bandwidth measurement results of NbN HEB mixers, which are employing NbN thin films grown on a GaN buffer-layer. The HEB mixers were operated in the heterodyne regime at a bath temperature of approximately 4.5 K and with a local oscillator operating at a frequency of 2 THz. A quantum cascade laser served as the local oscillator and a reference synthesizer based on a BWO generator (130-160 GHz) and a semiconductor superlattice (SSL) frequency multiplier was used as a signal source. By changing the LO frequency it was possible to record the IF response or gain bandwidth of the HEB with a spectrum analyzer at the operation point, which yielded lowest noise temperature. The gain bandwidth that was recorded in the heterodyne regime at 2 THz amounts to approximately 5 GHz and coincides well with a measurement that has been performed at elevated bath temperatures and lower LO frequency of 140 GHz. These findings strongly support that by using a GaN buffer-layer the phonon escape time of NbN HEBs can be significantly lower as compared to e.g. Si substrate, thus, providing higher gain bandwidth. |
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no |
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Serial |
1175 |
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| Author |
Cherednichenko, S.; Kroug, M.; Yagoubov, P.; Merkel, H.; Kollberg, E.; Yngvesson, K. S.; Voronov, B.; Gol’tsman, G. |
| Title |
IF bandwidth of phonon cooled HEB mixers made from NbN films on MgO substrates |
Type |
Conference Article |
| Year |
2000 |
Publication |
Proc. 11th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 11th Int. Symp. Space Terahertz Technol. |
| Volume |
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Issue |
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Pages |
219-227 |
| Keywords |
NbN HEB mixers, cinversion gain bandwidth, IF bandwidth |
| Abstract |
An investigation of gain and noise bandwidth of phonon-cooled hot-electron bolometric (HEB) mixers is presented. The radiation coupling to the mixers is quasioptical through either a spiral or twin-slot antenna. A maximum gain bandwidth of 4.8 GHz is obtained for mixers based on a 3.5 nm thin NbN film with Tc= 10 K. The noise bandwidth is 5.6 GHz, at the moment limited by parasitic elements in the, device mount fixture. At 0.65 THz the DSB receiver noise temperature is 700-800 К in the IF band 1-2 GHz, and 1150-2700 К in the band 3.5-7 GHz. |
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no |
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1557 |
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Schwaab, G.W.; Auen, K.; Bruendermann, E.; Feinaeugle, R.; Gol’tsman, G.N.; Huebers, H.-W.; Krabbe, A.; Roeser, H.-P.; Sirmain, G. |
| Title |
2- to 6-THz heterodyne receiver array for the Stratospheric Observatory for Infrared Astronomy (SOFIA) |
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Conference Article |
| Year |
1998 |
Publication |
Proc. SPIE |
Abbreviated Journal |
Proc. SPIE |
| Volume |
3357 |
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Pages |
85-96 |
| Keywords |
NbN HEB mixers, applications, stratospheric observatory, airborne |
| 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. |
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SPIE |
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Phillips, T.G. |
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Conference |
Advanced Technology MMW, Radio, and Terahertz Telescopes |
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no |
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Serial |
1583 |
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Hübers, H.-W.; Semenov, A.; Holldack, K.; Schade, U.; Wüstefeld, G.; Gol’tsman, G. |
| Title |
Time domain analysis of coherent terahertz synchrotron radiation |
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Journal Article |
| Year |
2005 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
| Volume |
87 |
Issue |
18 |
Pages |
184103 (1 to 3) |
| Keywords |
NbN HEB mixers, applications |
| Abstract |
The time structure of coherent terahertz synchrotron radiation at the electron storage ring of the Berliner Elektronensynchrotron und Speicherring Gesellschaft has been analyzed with a fast superconducting hot-electron bolometer. The emission from a single bunch of electrons was found to last ∼1500ps at frequencies around 0.4THz, which is much longer than the length of an electron bunch in the time domain (∼5ps). It is suggested that this is caused by multiple reflections at the walls of the beam line. The quadratic increase of the power with the number of electrons in the bunch as predicted for coherent synchrotron radiation and the transition from stable to bursting radiation were determined from a single storage ring fill pattern of bunches with different populations. |
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0003-6951 |
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no |
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1457 |
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Cherednichenko, S.; Khosropanah, P.; Berg, T.; Merkel, H.; Kollberg, E.; Drakinskiy, V.; Voronov, B.; Gol’tsman, G. |
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Optimization of HEB mixer for the Herschel Space Observatory |
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Abstract |
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2004 |
Publication |
Proc. 15th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 15th Int. Symp. Space Terahertz Technol. |
| Volume |
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Pages |
16 |
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NbN HEB mixers, applications |
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A mixer development for the HIFI instrument of the Herschel Space Observatory has come to the final stage. In our paper and conference presentation we will describe the most important details of the Band 6 Low and High Mixer Unit design. Special attention will be given to the optimization of the hot- electron bolometer mixer chip, which is based on 3.5nm NbN superconducting film on silicon. As the HEB’s local oscillator power requirements depend on the bolometer size, we have compared mixer noise temperature for different bolometer width- to- length ratio. A trade- off between mixer performance and local oscillator power requirements results in the mixer units equipped with optimized mixer chips, providing the largest coverage of the Band6 RF band with the lowest possible receiver noise. A short account of the beam pattern measurements of Band6 mixers will be given as well. |
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no |
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1490 |
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Hübers, H.-W.; Schubert, J.; Krabbe, A.; Birk, M.; Wagner, G.; Semenov, A.; Gol’tsman, G.; Voronov, B.; Gershenzon, E. |
| Title |
Parylene anti-reflection coating of a quasi-optical hot-electron-bolometric mixer at terahertz frequencies |
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Journal Article |
| Year |
2001 |
Publication |
Infrared Physics & Technology |
Abbreviated Journal |
Infrared Physics & Technology |
| Volume |
42 |
Issue |
1 |
Pages |
41-47 |
| Keywords |
NbN HEB mixers, anti-reflection coating |
| Abstract |
Parylene C was investigated as anti-reflection coating for silicon at terahertz frequencies. Measurements with a Fourier-transform spectrometer show that the transmittance of pure silicon can be improved by about 30% when applying a layer of Parylene C with a quarter wavelength optical thickness. The 10% bandwidth of this coating extends from 1.5 to 3 THz for a center frequency of 2.3–2.5 THz, where the transmittance is constant. Heterodyne measurements demonstrate that the noise temperature of a hot-electron-bolometric mixer can be reduced significantly by coating the silicon lens of the hybrid antenna with a quarter wavelength Parylene C layer. Compared to the same mixer with an uncoated lens the improvement is about 30% at a frequency of 2.5 THz. |
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1350-4495 |
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no |
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1548 |
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Huebers, H.-W.; Semenov, A.; Schubert, J.; Gol’tsman, G. N.; Voronov, B. M.; Gershenzon, E. M.; Krabbe, A.; Roeser, H.-P. |
| Title |
NbN hot-electron bolometer as THz mixer for SOFIA |
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Conference Article |
| Year |
2000 |
Publication |
Proc. SPIE |
Abbreviated Journal |
Proc. SPIE |
| Volume |
4014 |
Issue |
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Pages |
195-202 |
| Keywords |
NbN HEB mixers, airborne, stratospheric observatory, SOFIA |
| Abstract |
Heterodyne receivers for applications in astronomy need quantum limited sensitivity. We have investigated phonon- cooled NbN hot electron bolometric mixers in the frequency range from 0.7 THz to 5.2 THz. The devices were 3.5 nm thin films with an in-plane dimension of 1.7 X 0.2 micrometers 2 integrated in a complementary logarithmic spiral antenna. The best measured DSB receiver noise temperatures are 1300 K (0.7 THz), 2000 K (1.4 THz), 2100 K (1.6 THz), 2600 K (2.5 THz), 4000 K (3.1 THz), 5600 K (4.3 THz), and 8800 K (5.2 THz). The sensitivity fluctuation, the long term stability, and the antenna pattern were measured. The results demonstrate that this mixer is very well suited for GREAT, the German heterodyne receiver for SOFIA. |
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SPIE |
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Melugin, R.K.; Roeser, H.-P. |
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Airborne Telescope Systems |
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1554 |
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