| Records |
| Author |
Il'in, K. S.; Cherednichenko, S. I.; Gol'tsman, G. N.; Currie, M.; Sobolewski, R. |
| Title |
Comparative study of the bandwidth of phonon-cooled NbN hot-electron bolometers in submillimeter and optical wavelength ranges |
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Conference Article |
| Year |
1998 |
Publication |
Proc. 9th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 9th Int. Symp. Space Terahertz Technol. |
| Volume |
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Issue |
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Pages |
323-330 |
| Keywords |
NbN HEB mixers |
Abstract  |
We report the results of the bandwidth measurements of NbN hot-electron bolometers, perfomied in the terahertz frequency domain at 140 GHz and 660 GHz and in time domain in the optical range at the wavelength of 395 nm.. Our studies were done on 3.5-nm-thick NbN films evaporated on sapphire substrates and patterned into ilin-size microbridges. In order to measure the gain bandwidth, we used two identical BWOs (140 or 660 GHz), one functioning as a local oscillator and the other as a signal source. The bandwidth we achieved was 3.5-4 GHz at 4.2 K with the optimal LO and DC biases. Time-domain measurements with a resolution below 300 fs were performed using an electro-optic sampling system, in the temperature range between 4.2 K to 9 K at various values of the bias current and optical power. The obtained response time of the NbN hot-electron bolometer to —100- fs-wide Ti:sapphire laser pulses was about 27 ps, what corresponds to the 5.9 GHz gain bandwidth. |
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1590 |
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Shurakov, A.; Tong, C.-Y. E.; Blundell, R.; Kaurova, N.; Voronov, B.; Gol'tsman, G. |
| Title |
Microwave stabilization of a HEB mixer in a pulse-tube cryocooler |
Type |
Journal Article |
| Year |
2013 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
| Volume |
23 |
Issue |
3 |
Pages |
1501504-1501504 |
| Keywords |
NbN HEB mixers |
| Abstract |
We report the results of our study of the stability of an 800 GHz hot electron bolometer (HEB) mixer cooled with a pulse-tube cryocooler. Pulse-tube cryocoolers introduce temperature fluctuations as well as mechanical vibrations at a frequency of ~1 Hz, both of which can cause receiver gain fluctuations at that frequency. In our system, the motor of the cryocooler was separated from the cryostat to minimize mechanical vibrations, leaving thermal effects as the dominant source of the receiver gain fluctuations. We measured root mean square temperature variations of the 4 K stage of ~7 mK. The HEB mixer was pumped by a solid state local oscillator at 810 GHz. The root mean square current fluctuations at the low noise operating point (1.50 mV, 56.5 μA) were ~0.12 μA, and were predominantly due to thermal fluctuations. To stabilize the bias current, microwave radiation was injected to the HEB mixer. The injected power level was set by a proportional-integral-derivative controller, which completely compensates for the bias current oscillations induced by the pulse-tube cryocooler. Significant improvement in the Allan variance of the receiver output power was obtained, and an Allan time of 5 s was measured. |
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1051-8223 |
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1372 |
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Hajenius, M.; Yang, Z. Q.; Gao, J. R.; Baselmans, J. J. A.; Klapwijk, T. M.; Voronov, B.; Gol'tsman, G. |
| Title |
Optimized sensitivity of NbN hot electron bolometer mixers by annealing |
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Journal Article |
| Year |
2007 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
| Volume |
17 |
Issue |
2 |
Pages |
399-402 |
| Keywords |
NbN HEB mixers |
| Abstract |
We report that the heterodyne sensitivity of superconducting hot-electron bolometers (HEBs) increases by 25-30% after annealing at 85degC in high vacuum. The devices studied are twin-slot antenna coupled mixers with a small area NbN bridge of 1 mum times 0.15 mum, above which there is a SiO 2 passivation layer. The mixer noise temperature, gain, and resistance versus temperature curve of a HEB before and after annealing are compared and analysed. We show that the annealing reduces the intrinsic noise of the mixer by 37% and makes the superconducting transition of the bridge and the contacts sharper. We argue that the reduction ofthe noise is mainly due to the improvement of the transparency of the contact/film interface. The lowest receiver noise temperature of 700 K is measured at a local oscillator frequency of 1.63 THz and at a bath temperature of 4.2 K. |
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1051-8223 |
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1426 |
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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 |
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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. D.; Gousev, Y. P.; Nebosis, R. S.; Renk, K. F.; Yagoubov, P.; Voronov, B. M.; Gol’tsman, G. N.; Syomash, V. D.; Gershenzon, E. M. |
| Title |
Heterodyne detection of THz radiation with a superconducting hot‐electron bolometer mixer |
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Journal Article |
| Year |
1996 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
| Volume |
69 |
Issue |
2 |
Pages |
260-262 |
| Keywords |
NbN HEB mixers |
| Abstract |
We report on the use of a superconducting hot‐electron bolometer mixer for heterodyne detection of terahertz radiation. Radiation with a wavelength of 119 μm was coupled to the mixer, a NbN microbridge, by a hybrid quasioptical antenna consisting of an extended hyperhemispherical lens and a planar logarithmic spiral antenna. We found, at an intermediate frequency of 1.5 GHz, a system double side band noise temperature of ≊40 000 K and conversion losses of 25 dB. We also discuss the possibilities of further improvement of the mixer performance. |
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0003-6951 |
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1610 |
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