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- Cherednichenko, Serguei, 1970, et al.
(författare)
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Hot-electron bolometer terahertz mixers for the Herschel Space Observatory
- 2008
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 79:034501, s. 034501-1 to 034501-10-
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Tidskriftsartikel (refereegranskat)abstract
- We report on low noise terahertz mixers (1.4–1.9 THz) developed for the heterodyne spectrometer onboard the Herschel Space Observatory. The mixers employ double slot antenna integrated superconducting hot-electron bolometers (HEBs) made of thin NbN films. The mixer performancewas characterized in terms of detection sensitivity across the entire rf band by using a Fourier transform spectrometer (from 0.5 to 2.5 THz, with 30 GHz resolution) and also by measuring the mixer noise temperature at a limited number of discrete frequencies. The lowest mixer noise temperature recorded was 750 K (double sideband (DSB)) at 1.6 THz and 950 K DSB at 1.9 THz local oscillator (LO) frequencies. Averaged across the intermediate frequency band of 2.4–4.8 GHz,the mixer noise temperature was 1100 K DSB at 1.6 THz and 1450 K DSB at 1.9 THz LO frequencies. The HEB heterodyne receiver stability has been analyzed and compared to the HEBstability in the direct detection mode. The optimal local oscillator power was determined and found to be in a 200–500 nW range.
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- Cherednichenko, Serguei, 1970, et al.
(författare)
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The Direct Detection Effect in the Hot-Electron Bolometer Mixer Sensitivity Calibration
- 2007
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 55:3, s. 504-510
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Tidskriftsartikel (refereegranskat)abstract
- We investigate an error in the noise temperature measurements of the hot-electron bolometer mixers caused by the so-called "direct detection effect". The effect originates in the changing of the mixer parameters when the mixer is loaded on calibration black body sources at different temperatures (300 and 77 K). A correction factor was obtained from the mixer output power versus the bias current dependence, measured by: 1) the local oscillator (LO) power tuning: 2) mixer heating: and 3) application of an external RF source. Furthermore, the direct detection effect was assessed by elimination of the heterodyne response using a LO frequency, which is far off the mixer RF band. We show that the direct detection effect can be mitigated by using an isolator between the mixer and the IF amplifier.
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- Deleniv, Anatoli, 1969, et al.
(författare)
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Experimental characterization of the 3rd order nonlinearities in thin film parallel-plate ferroelectric varactors
- 2007
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Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 1424406889 ; 2, s. 683-686
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Konferensbidrag (refereegranskat)abstract
- The 3rd order nonlinearities in parallel-plate ferroelectric varactors based on thin Ba0.25Sr0.75TiO3 epitaxial films are characterized in wide temperature range. Both, the generated 3rd order harmonic and 3rd order intermodulation products are measured experimentally. The 3rd harmonic IP3 at room temperature is measured to be 35dBm and is favorable as compared to semiconductor competitors. The good agreement between harmonic balance simulation and measured data indicate that the measured low frequency C-V is adequate for accurate design of nonlinear components.
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- Gevorgian, Spartak, 1948, et al.
(författare)
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Tunable ferroelectric resonator arrangement
- 2006
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- The present invention relates to a tunable resonating arrangement comprising a resonator apparatus (10), input/output coupling (4) means for coupling electromagnetic energy into/out of the resonator apparatus, and a tuning device (3) for application of a biasing voltage/electric field to the resonator apparatus. The resonator apparatus comprises a first resonator (1) and a second resonator (2). Said first resonator is non-tunable and said second resonator is tunable and comprises a ferroelectric substrate (21). Said first and second resonators are separated by a ground plane (13) which is common for said first and second resonators, and coupling means (5) are provided for providing coupling between said first and second resonators. For tuning of the resonator apparatus, the biasing voltage/electric field is applied to the second resonator (2)
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- Khosropanah, Pourya, 1971, et al.
(författare)
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Analysis of NbN Hot Electron Bolometer Receiver Noise Temperatures Above 2 THz With a Quantum Noise Model
- 2009
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Ingår i: IEEE Transactions on Applied Superconductivity. - 1558-2515 .- 1051-8223. ; 19:3, s. 274-277
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Tidskriftsartikel (refereegranskat)abstract
- This paper summarizes our receiver noise temperature data of NbN HEB mixers obtained at a number of local oscillator frequencies between 1.9 to 4.3 THz in order to verify the role of quantum noise. The experimental data show that the receiver noise temperature increases roughly linearly with frequency. At 4.3 THz, we measured a receiver noise temperature of 1300 K, which is about 6 times (hf/k B) . The noise data at different frequencies are compared to a prediction of a noise model including the contribution of quantum noise and making use of a hot-spot model for mixing. We draw a preliminary conclusion that at 4.3 THz roughly 30% of the receiver noise temperature can be ascribed to the quantum noise. However, more dedicated measurements are required in order to further support the quantum noise model for HEB mixers.
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- Kollberg, Erik, 1937, et al.
(författare)
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Quantum noise contribution to NbN hot electron bolometer receiver
- 2009
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Ingår i: Proceedings of the 20th International Symposium on Space Terahertz Technology, Charlottesville, 20-22 April 2009. ; , s. 155-
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Konferensbidrag (refereegranskat)abstract
- Abstract— Superconducting NbN hot electron bolometer (HEB) mixers are so far the most sensitive detectors forheterodyne spectroscopy in the frequency range between 1.5 THz and 5 THz. To reach the ultimate receiver noisetemperatures in the high end of the THz range (3-6 THz), it is crucial to understand their fundamental noise contributionfrom different origins. With increasing frequency, the classical output noise contribution should remain unchanged, butthe quantum noise contribution is expected to play an increasing role [1].This paper reports the first dedicated experiment using a single NbN HEB mixer at a number of local oscillatorfrequencies between 1.6 to 4.3 THz to address and quantify the contribution of the quantum noise to the receiver noisetemperature.We used a spiral antenna coupled NbN HEB mixer with a bolometer size of 2 μm×0.2 μm. In order to minimizeuncertainties in the corrections of the optical losses, we use a vacuum hot/cold load setup [2] to eliminate the air loss, andan uncoated elliptical Si lens. Although other components, a 3 μm Mylar beam splitter and a QMC heat filter, alsointroduce frequency dependent optical losses, they can be accurately calibrated. Furthermore, to reduce uncertainties inthe data, we measure Y-factors responding to the hot/cold load by fixing the voltage, but varying the LO power [2]. AsLO, we use a FIR gas laser.We measure the Y-factor at the optimal point at different frequencies by only varying LO frequencies, but keepingthe rest exactly the same. We obtain DSB receiver noise temperatures, which are 842 K (at 1.6 THz), 845 K (1.9 THz), 974K (2.5 THz) and 1372 K (4.3 THz). After the correction for the losses of the QMC filter and the beam splitter, the noisedata show a linear increase with increasing frequency.Using a quantum noise model [1] for HEB mixers and using a criterion for which the classical output noise must beconstant at different frequencies, we analyze the results and find the excess quantum noise factor β to be around 2 andthat 24 % of the total receiver noise temperature at 4.3 THz (at the input of the entire receiver) can be ascribed toquantum noise. Clearly the quantum noise has a small but measurable effect on the receiver noise temperature at thisfrequency.We are still analyzing different alternatives of interpretation for the mismatch loss between the bolometer andthe spiral antenna.[1] E. L. Kollberg and K. S. Yngvesson, “Quantum-noise theory for terahertz hot electron bolometer mixers,” IEEE Trans.Microwave Theory and Techniques, 54, 2077, 2006.[2] P. Khosropanah, J.R. Gao, W.M. Laauwen, M. Hajenius and T.M. Klapwijk, “Low noise NbN hot-electron bolometer mixerat 4.3 THz,” Appl. Phys. Lett., 91, 221111, 2007.
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| 9. |
- Kollberg, Erik, 1937, et al.
(författare)
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Quantum-Noise Theory for Terahertz Hot Electron Bolometer Mixers
- 2006
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. ; 54:5, s. 2077-2089
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Tidskriftsartikel (refereegranskat)abstract
- Abstract In this paper we first review general quantum mechanical limits on the sensitivity of heterodyne receivers. The main aim of the paper is to explore the quantum noise properties of Hot Electron Bolometric (HEB) mixers. HEB mixers have a characteristic feature not found in other mixers: based on the hot-spot model, the conversion loss varies along the length dimension of the bolometer, and some sections of the bolometer are essentially passive, in which little frequency conversion occurs. We analyze a quantitative distributed quantum noise model of the HEB mixer, making use of simulated hot spot model data, that takes into account the continuous variation of the sensitivity along the bolometer bridge. An expression for the HEB receiver noise temperature, including optical input loss, is derived. We find that the predicted DSB receiver noise temperature agrees well with the available measured data (up to 5.3 THz). The results of our analysis suggest that quantum noise and classical HEB noise contribute about equally at 3 THz while at higher terahertz frequencies quantum noise dominates. Quantum noise thus appears to show measurable effects in existing HEB mixers, and will be even more important to take into account as HEB mixers continue to be developed for higher terahertz frequencies.
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