| Records |
| Author |
Loudkov, D.; Tong, C.-Y. E.; Blundell, R.; Kaurova, N.; Grishina, E.; Voronov, B.; Gol’tsman, G. |
| Title |
An investigation of the performance of the superconducting HEB mixer as a function of its RF embedding impedance |
Type |
Journal Article |
| Year |
2005 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
| Volume |
15 |
Issue |
2 |
Pages |
472-475 |
| Keywords |
waveguide NbN HEB mixers |
| Abstract |
We have conducted an investigation of the optimal embedding impedance for a waveguide superconducting hot-electron bolometric (HEB) mixer. Three mixer chip designs for 800 GHz, offering nominal embedding resistances of 70 /spl Omega/, 35 /spl Omega/, and 15 /spl Omega/, have been developed. We used both High Frequency Structure Simulator (HFSS) software and scale model impedance measurements in the design process. We subsequently fabricated HEB mixers to these designs using 3-4 nm thick NbN thin film. Receiver noise temperature measurements and Fourier Transform Spectrometer (FTS) scans were performed to determine the optimal combination of embedding impedance and normal-state resistance for a 50 Ohm IF load impedance. A receiver noise temperature of 440 K was measured at a local oscillator frequency 850 GHz for a mixer with normal state resistance of 62 /spl Omega/ incorporated into a circuit offering a nominal embedding impedance of 70 /spl Omega/. We conclude from our data that, for low noise operation, the normal state resistance of the HEB mixer element should be close to the embedding impedance of the mixer mount. |
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1439677 |
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1464 |
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| Author |
Tong, C.-Y. E.; Trifonov, A.; Shurakov, A.; Blundell, R.; Gol’tsman, G. |
| Title |
A microwave-operated hot-electron-bolometric power detector for terahertz radiation |
Type |
Journal Article |
| Year |
2015 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
| Volume |
25 |
Issue |
3 |
Pages |
2300604 (1 to 4) |
| Keywords |
NbN HEB mixer |
| Abstract |
A new class of microwave-operated THz power detectors based on the NbN hot-electron-bolometer (HEB) mixer is proposed. The injected microwave signal ( 1 GHz) serves the dual purpose of pumping the HEB element and enabling the read-out of the internal state of the device. A cryogenic amplifier amplifies the reflected microwave signal from the device and a homodyne scheme recovers the effects of the incident THz radiation. Two modes of operation have been identified, depending on the level of incident radiation. For weak signals, we use a chopper to chop the incident radiation against a black body reference and a lock-in amplifier to perform synchronous detection of the homodyne readout. The voltage measured is proportional to the incident power, and we estimate an optical noise equivalent power of 5pW/ √Hz at 0.83 THz. At higher signal levels, the homodyne circuit recovers the stream of steady relaxation oscillation pulses from the HEB device. The frequency of these pulses is in the MHz frequency range and bears a linear relationship with the incident THz radiation over an input power range of 15 dB. A digital frequency counter is used to measure THz power. The applicable power range is between 1 nW and 1 μW. |
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1558-2515 |
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no |
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1354 |
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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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1558-2515 |
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1331 |
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| Author |
Kawamura, J.; Blundell, R.; Tong, C.-Y. E.; Gol'tsman, G.; Gershenzon, E.; Voronov, B. |
| Title |
NbN hot-electron mixer measurements at 200 GHz |
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Conference Article |
| Year |
1995 |
Publication |
Proc. 6th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 6th Int. Symp. Space Terahertz Technol. |
| Volume |
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Issue |
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Pages |
254-261 |
| Keywords |
NbN HEB mixers |
| Abstract |
We present noise and gain measurements of resistively driven NbN hot-electron mixers near 200 GHz. The device geometry is chosen so that the dominant cooling process of the hot-electrons is their interaction with the lattice. Except for a single batch, the intermediate frequency cut-off of these mixer elements is – 3 700 MHz, and has shown little variation among other batches of devices. At 100 MHz we measured intrinsic mixer losses as low as —3 dB. We measured the noise temperatures at several intermediate frequencies, and for the best de- vice at 137 MHz with 20 MHz bandwidth, we measured 2000 K; using a low-noise first- stage amplifier at 1.5 GHz with 200 MHz bandwidth, the receiver noise temperature measured 2800 K. We estimate that the noise contribution from the mixer is 500 K and the total losses are —15 dB at 137 MHz. |
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1626 |
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Kawamura, J.; Blundell, R.; Tong, C.-Y. E.; Golts'man, G.; Gershenzon, E.; Voronov B. |
| Title |
Superconductive NbN hot-electron bolometric mixer performance at 250 GHz |
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Conference Article |
| Year |
1996 |
Publication |
Proc. 7th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 7th Int. Symp. Space Terahertz Technol. |
| Volume |
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Issue |
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Pages |
331-336 |
| Keywords |
NbN HEB mixers |
| Abstract |
Thin film NbN (<40 A) strips are used as waveguide mixer elements. The electron cooling mechanism for the geometry is the electron-phonon interaction. We report a receiver noise temperature of 750 K at 244 GHz, with / IF = 1.5 GHz, Af= 500 MHz, and Tphysical = 4 K. The instantaneous bandwidth for this mixer is 1.6 GHz. The local oscillator (LO) power is 0.5 1.tW with 3 dB-uncertainty. The mixer is linear to 1 dB up to an input power level 6 dB below the LO power. We report the first detection of a molecular line emission using this class of mixer, and that the receiver noise temperature determined from Y-factor measurements reflects the true heterodyne sensitivity. |
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945 |
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