ESPRIT: a study concept for a far-infrared interferometer in space

Wild, Wolfgang; Graauw, Th. de; Helmich, Frank; Baryshev, A.; Cernicharo, J.; Gao, J. R.; Gunst, A. W.; Boś, A.; Herder, J. W. den; Jackson, B. D.; Koshelets, V. P.; Langevelde, H. J. van; Maat, P.; Martı́n-Pintado, J.; Noordam, J. E.; Roelfsema, Peter; Venema, Lars; Wesselius, P. R.; Yagoubov, P.

doi:10.1117/12.789603

Cited by 13 publications

(9 citation statements)

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“…[1][2][3][4] These detectors will be used on the Herschel space telescope 5 and are required in various future conceptual space missions. 6 Another type of detector, the superconducting single photon detector ͑SSPD͒, 7 is based on similar films and is ultrafast and sensitive for the detection of both visible and infrared photons. SSPDs can perform high speed photon counting which has many applications, for example, optical communications and quantum information.…”

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confidence: 99%

Monocrystalline NbN nanofilms on a 3C-SiC∕Si substrate

Gao

Hajenius

Tichelaar

et al. 2007

Applied Physics Letters

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The authors have realized NbN ͑100͒ nanofilms on a 3C-SiC ͑100͒/Si͑100͒ substrate by dc reactive magnetron sputtering at 800°C. High-resolution transmission electron microscopy ͑HRTEM͒ is used to characterize the films, showing a monocrystalline structure and confirming epitaxial growth on the 3C-SiC layer. A film ranging in thickness from 3.4 to 4.1 nm shows a superconducting transition temperature of 11.8 K, which is the highest reported for NbN films of comparable thickness. The NbN nano-films on 3C-SiC offer a promising alternative to improve terahertz detectors. For comparison, NbN nanofilms grown directly on Si substrates are also studied by HRTEM. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2766963͔The ability to grow superconducting NbN films of several nanometer thick is of significant importance to the development of modern photon detector technology. Superconducting hot electron bolometer ͑HEB͒ mixers based on such nanofilms are the only sensitive heterodyne detectors for high-resolution spectroscopy at frequencies between 1.5 and 6 THz.1-4 These detectors will be used on the Herschel space telescope 5 and are required in various future conceptual space missions. 6 Another type of detector, the superconducting single photon detector ͑SSPD͒, 7 is based on similar films and is ultrafast and sensitive for the detection of both visible and infrared photons. SSPDs can perform high speed photon counting which has many applications, for example, optical communications and quantum information.To date, HEB mixers are based on ultrathin NbN films grown primarily on substrates such as Si with its native oxide, 2-4 MgO, 8 and Si with a buffering MgO film. 9 SSPDs are based on NbN films grown on sapphire substrates. For films with an intended thickness of 3.5 nm ͑not directly measured͒, the highest superconducting transition temperatures ͑T c ͒ are reported to be 9.5-11 K.9 Among them, NbN films on MgO, MgO buffer layers and sapphire substrates have higher T c than NbN films on Si substrates. These substrates allow for epitaxial growth of the NbN films, 8-10 resulting in a monocrystalline structure. For HEB mixers, Si is a preferred substrate because of its low loss at terahertz frequencies, well-established processing technology, and inherent reliability. However, the drawback to using Si in this case is the limited intermediate frequency bandwidth, which is set by the thermal time constant.In this letter, we demonstrate superconducting NbN nanofilms on a 3C-SiC buffered Si substrate. The films were characterized by high-resolution transmission electron microscopy ͑HRTEM͒. In addition, the superconducting properties were measured.The 3C-SiC buffer layers were heteroepitaxially grown on Si ͑100͒ substrates by atmospheric pressure chemical vapor deposition at 1280°C using a process described in detail elsewhere.11 To ensure reasonably good crystal quality near the top surface of the 3C-SiC layer given its lattice mismatch with Si, we choose a thickness of 1 m for 3C-SiC layer. As reported previously, 11 t...

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confidence: 99%

Monocrystalline NbN nanofilms on a 3C-SiC∕Si substrate

Gao

Hajenius

Tichelaar

et al. 2007

Applied Physics Letters

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“…Due to the limited availability of dry cryocoolers and electrical power for both space-based 29 and airborne missions, 4,30 we foresee several technical challenges with regard to the use of terahertz QCLs as LOs. First, the input dc power has to be far below 100 mW if it is operated around 5-10 K. An alternative is to have a terahertz QCL operated at a relatively high temperature, e.g., 70 K or higher, where the required input power is moderately reduced to as much as ϳ1 W. 29 Lower dc input power 31 and higher operating temperature 32 terahertz QCLs have been demonstrated in the literature. Another key step toward realizing terahertz QCL LOs is the development of frequency or phase locking techniques.…”

Section: Discussionmentioning

confidence: 99%

3.4 THz heterodyne receiver using a hot electron bolometer and a distributed feedback quantum cascade laser

Khosropanah

Zhang

Hovenier

et al. 2008

Journal of Applied Physics

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We report a heterodyne receiver using a superconducting NbN hot electron bolometer ͑HEB͒ integrated with a tight winding spiral antenna as mixer and a distributed feedback ͑DFB͒ terahertz quantum cascade laser ͑QCL͒ operating at 3.42 THz as local oscillator. The aim is to demonstrate the readiness of both devices for the detection of OH lines at 3.5 THz in a real instrument. We show that the improved single-spot beam of the terahertz QCL can easily pump the HEB mixer. We measured a double sideband receiver noise temperature of 2100 K at the optimum local oscillator power of 290 nW. This noise temperature can be further reduced to 1100 K if we correct the loss due to the use of an uncoated lens, and the losses of the window and the air. Therefore, the combination of a HEB and such a DFB QCL can in principle be used to detect an OH line at 3.5 THz. However, a high input power of several watts, which is needed to operate the QCL in a liquid-helium cryostat, poses a big challenge to the receiver stability.

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“…A distributed correlator as proposed in [1] could be an attractive implementation. In this concept each satellite has a correlator on board resulting in several advantages.…”

Section: Signal Correlationmentioning

confidence: 99%

“…This is quite different from a direct detection interferometer which requires much lower temperatures for the telescope, optics and -depending on the type of detectors -also for the detectors. For the ESPRIT study concept, a first estimate of the required cooling has been made [1]. It shows that for a heterodyne interferometer the cooling requirements are not too demanding and probably within reach of presently on-going cooling technology developments.…”

Section: Cryo-coolingmentioning

confidence: 99%

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Far-infrared heterodyne interferometry from space

Wild

Helmich

2008

SPIE Proceedings

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Many studies on the formation of stars and planets require high angular and high spectral resolution in the far-infrared regime. Even with the upcoming operation of the Herschel Space Observatory, ALMA, and JWST, angular resolutions of better than 1 arcsec combined with high spectral resolution in the crucial far-infrared domain of 1 THz to ~ 10 THz (300 µm to 30 µm) are still beyond observational reach. Only a far-infrared heterodyne interferometer can close this gap.Here we present the general requirements for a FIR heterodyne interferometer in space and address a number of critical key technologies needed for such an instrument.

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ESPRIT: a study concept for a far-infrared interferometer in space

Cited by 13 publications

References 2 publications

Monocrystalline NbN nanofilms on a 3C-SiC∕Si substrate

Monocrystalline NbN nanofilms on a 3C-SiC∕Si substrate

3.4 THz heterodyne receiver using a hot electron bolometer and a distributed feedback quantum cascade laser

Far-infrared heterodyne interferometry from space

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