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| Author | Trifonov, A.; Tong, C.-Y. E.; Lobanov, Y.; Kaurova, N.; Blundell, R.; Goltsman, G. | ||||
| Title | Gap frequency and photon absorption in a hot electron bolometer | Type | Conference Article | ||
| Year | 2016 | Publication | Proc. 27th Int. Symp. Space Terahertz Technol. | Abbreviated Journal | Proc. 27th Int. Symp. Space Terahertz Technol. |
| Volume | Issue | Pages | 121 | ||
| Keywords | NbN HEB; Si membrane | ||||
Abstract  |
The superconducting energy gap is a crucial parameter of a superconductor when used in mixing applications. In the case of the SIS mixer, the mixing process is efficient for frequencies below the energy gap, whereas, in the case of the HEB mixer, the mixing process is most efficient at frequencies above the gap, where photon absorption takes place more readily. We have investigated the photon absorption phenomenon around the gap frequency of HEB mixers based on NbN films deposited on silicon membranes. Apart from studying the pumped I-V curves of HEB devices, we have also probed them with microwave radiation, as previously described [1]. At frequencies far below the gap frequency, the pumped I-V curves show abrupt switching between the superconducting and resistive states. For the NbN HEB mixers we tested, which have critical temperatures of ~9 K, this is true for frequencies below about 400 GHz. As the pump frequency is increased beyond 400 GHz, the resistive state extends towards zero bias and at some point a small region of negative differential resistance appears close to zero bias. In this region, the microwave probe reveals that the device impedance is changing randomly with time. As the pump frequency is further increased, this random impedance change develops into relaxation oscillations, which can be observed by the demodulation of the reflected microwave probe. Initially, these oscillations take the form of several frequencies grouped together under an envelope. As we approach the gap frequency, the multiple frequency relaxation oscillations coalesce into a single frequency of a few MHz. The resultant square-wave nature of the oscillation is a clear indication that the device is in a bi-stable state, switching between the superconducting and normal state. Above the gap frequency, it is possible to obtain a pumped I-V curve with no negative differential resistance above a threshold pumping level. Below this pumping level, the device demonstrates bi-stability, and regular relaxation oscillation at a few MHz is observed as a function of pump power. The threshold pumping level is clearly related to the amount of power absorbed by the device and its phonon cooling. From the above experiment, we can derive the gap frequency of the NbN film, which is 585 GHz for our 6 μm thin silicon membrane-based device. We also confirm that the HEB mixer is not an efficient photon absorber for radiation below the gap frequency. 1. A. Trifonov et al., “Probing the stability of HEB mixers with microwave injection”, IEEE Trans. Appl. Supercond., vol. 25, no. 3, June 2015. | ||||
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| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1204 | |||
| Permanent link to this record | |||||
| Author | Trifonov, A.; Tong, C.-Y. E.; Lobanov, Y.; Kaurova, N.; Blundell, R.; Goltsman, G. | ||||
| Title | Photon absorption near the gap frequency in a hot electron bolometer | Type | Journal Article | ||
| Year | 2017 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume | 27 | Issue | 4 | Pages | 1-4 |
| Keywords | NBN HEB mixer | ||||
| Abstract |
The superconducting energy gap is a fundamental characteristic of a superconducting film, which, together with the applied pump power and the biasing setup, defines the instantaneous resistive state of the Hot Electron Bolometer (HEB) mixer at any given bias point on the I-V curve. In this paper we report on a series of experiments, in which we subjected the HEB to radiation over a wide frequency range along with parallel microwave injection. We have observed three distinct regimes of operation of the HEB, depending on whether the radiation is above the gap frequency, far below it or close to it. These regimes are driven by the different patterns of photon absorption. The experiments have allowed us to derive the approximate gap frequency of the device under test as about 585 GHz. Microwave injection was used to probe the HEB impedance. Spontaneous switching between the superconducting (low resistive) state and a quasi-normal (high resistive) state was observed. The switching pattern depends on the particular regime of HEB operation and can assume a random pattern at pump frequencies below the gap to a regular relaxation oscillation running at a few MHz when pumped above the gap. | ||||
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| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1558-2515 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1331 | |||
| Permanent link to this record | |||||
| Author | Khosropanah, Pourya | ||||
| Title | NbN and NbTiN hot electron bolometer THz mixers | Type | Book Whole | ||
| Year | 2003 | Publication | Chalmers University of Technology | Abbreviated Journal | |
| Volume | Issue | Pages | |||
| Keywords | HEB mixer, hot electron bolometer mixer, NbN, NbTiN, superconducting detector, heterodyne receiver, THz mixer, submillimeter mixer, quasioptical receiver, double slot antenna, twin slot antenna, spiral antenna, receiver noise, FTS, Fourier Transform Spectrometer | ||||
| Abstract |
The thesis reports the development of Hot Electron Bolometer (HEB) mixers for radio astronomy heterodyne receivers in THz frequency range. Part of this work is the fabrication of HEB devices, which are based on NbN or NbTiN superconducting thin films (â‰<a4>5 nm). They are integrated with wideband spiral or double-slot planar antennas. The mixer chips are incorporated into a quasi-optical receiver. The experimental part of this work focuses on the characterization of the receiver as a whole, and the HEB mixers as a part. Double side band receiver noise temperature and the IF bandwidth are reported for frequencies from 0.7 THz up to 2.6 THz. The spectrum of the direct response of HEB integrated with dierent antennas are measured using Fourier Transform Spectrometer (FTS). The effect of the bolometer size on total receiver performance and the LO power requirements is also discussed. A high-yield and reliable process for fabrication of NbN HEB mixers have been achieved. Over 100 devices with different bolometer geometry, film property and also different antennas have been fabricated and measured. The measured data enables us to discuss the impact of different parameters to the receiver overall performance. This work has provided NbN HEB mixers to the following receivers: TREND (Terahertz REceiver with NbN HEB Device) operating at 1.25-1.5 THz, installed in AST/RO Submillimeter Wave Telescope, Amundsen/Scott South Pole Station, in 2002-2003. Band 6-low (1.410-1.700 THz) and 6-high (1.700-1.920 THz) of the HIFI (Heterodyne Instrument for Far Infra-red) in the Herschel Space Observatory, due to launch in 2007 by ESA (European Space Agency). Besides, there has been continuous efforts to develop better models to explain the mixer performance more accurately. They are based on two temperature model for electrons and phonons and solving one-dimensional heat balance equations along the bolometer. The principles of these models are illustrated and the calculated results are compared with measured data. |
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| Address | |||||
| Corporate Author | Thesis | Ph.D. thesis | |||
| Publisher | Chalmers University of Technology | Place of Publication | Göteborg | Editor | |
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| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 910 | |||
| Permanent link to this record | |||||
| Author | Hübers, H.-W.; Semenov, A.; Holldack, K.; Schade, U.; Wüstefeld, G.; Gol’tsman, G. | ||||
| Title | Time domain analysis of coherent terahertz synchrotron radiation | Type | 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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| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 0003-6951 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1457 | |||
| Permanent link to this record | |||||
| Author | Gol’tsman, G. N.; Kouminov, P. B.; Goghidze, I. G.; Karasik, B. S.; Gershenzon, E. M. | ||||
| Title | Nonbolometric and fast bolometric responses of YBaCuO thin films in superconducting, resistive, and normal states | Type | Conference Article | ||
| Year | 1994 | Publication | Proc. SPIE | Abbreviated Journal | Proc. SPIE |
| Volume | 2159 | Issue | Pages | 81-86 | |
| Keywords | YBCO HTS HEB, nonbolornetric | ||||
| Abstract |
The transient voltage response in both epitaxial and granular YBaCuO thin films to 20 ps pulses of YAG:Nd laser radiation with 0.63 micrometers and 1.54 micrometers was studied. In normal and resistive states both types of films demonstrate two components: nonequilibrium picosecond component and following bolometric nanosecond. The normalized amplitudes are almost the same for all films. In superconducting state we observed a kinetic inductive response and two-component shape after integration. The normalized amplitude of the response in granular films is up to several orders of magnitude larger than in epitaxial films. We interpret the nonequilibrium response in terms of a suppression of order parameter by the excess of quasiparticles followed by the change of resistance in normal and resistive states or kinetic inductance in superconducting state. The sharp rise of inductive response in granular films is explained both by a diminishing of the crossection for current percolation through the disordered network os Josephson weak links and by a decrease of condensate density in neighboring regions. | ||||
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| Publisher | SPIE | Place of Publication | Editor | Nahum, M.; Villegier, J.-C. | |
| Language | Summary Language | Original Title | |||
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| Area | Expedition | Conference | High-Temperature Superconducting Detectors: Bolometric and Nonbolometric | ||
| Notes | Approved | no | |||
| Call Number | Serial | 1641 | |||
| Permanent link to this record | |||||