4.7-THz Superconducting Hot Electron Bolometer Waveguide Mixer

Büchel, D.; Pütz, P.; Jacobs, K.; Schultz, Michael; Graf, U. U.; Risacher, C.; Richter, Heiko; Ricken, Oliver; Hübers, Heinz‐Wilhelm; Güsten, R.; Honingh, C. E.; Stützki, J.

doi:10.1109/tthz.2014.2382434

Cited by 52 publications

(41 citation statements)

References 28 publications

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“…For compactness and clarity, imaging elements are drawn as lenses, although mirrors are more commonly used in real instruments layer was further optimized to thinner layers in order to meet the LO requirements of the array. In comparison to the devices fabricated for the GREAT H channel [23], the LO power requirement was reduced by a factor of 3. HEB microbridge dimensions where reduced from 5.5 x 300 x 3600 to 3.5 nm x 200 nm x 3250 nm with an impedance required by the on-chip circuit of 120 Ohms.…”

Section: Fig 8 Schematic Beam Path Using Two Gaussian Telescopes Fomentioning

confidence: 98%

“…A significant improvement can be seen in the receiver performance in Table I and is explained by various upgrades: 1) improved optics, 2) better hot electron bolometer (HEB) detectors 3) higher output power local oscillator solid state chains. Most noticeably, a new receiver band based on waveguide HEB mixers, was added in 2014 [23], opening the [OI] 4.7 THz band for high-resolution spectroscopy for the first time since the pioneering Kuiper Airborne Observatory (KAO) in 1988-1995 [24].…”

Section: The Great/upgreat Receiversmentioning

confidence: 99%

“…The mixers for the HFA receiver are based on the Hchannel HEB mixer [23]. As for the LFA, the HFA devices will use the same wafer with thinner NbN as compared to the H channel mixers.…”

Section: ) Hfa Heb Mixersmentioning

confidence: 99%

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First Supra-THz Heterodyne Array Receivers for Astronomy With the SOFIA Observatory

Risacher

Güsten

Stützki³

et al. 2016

IEEE Trans. THz Sci. Technol.

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Abstract-We present the upGREAT THz heterodyne arrays for far-infrared astronomy. The Low Frequency Array (LFA) is designed to cover the 1.9-2.5 THz range using 2x7-pixel waveguide-based HEB mixer arrays in a dual polarization configuration. The High Frequency Array (HFA) will perform observations of the [OI] line at ~4.745 THz using a 7-pixel waveguide-based HEB mixer array. This paper describes the common design for both arrays, cooled to 4.5 K using closedcycle pulse tube technology. We then show the laboratory and telescope characterization of the first array with its 14 pixels (LFA), which culminated in the successful commissioning in May 2015 aboard the SOFIA airborne observatory observing the [CII] fine structure transition at 1.905 THz. This is the first successful demonstration of astronomical observations with a heterodyne focal plane array above 1 THz and is also the first time highpower closed-cycle coolers for temperatures below 4.5 K are operated on an airborne platform.

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Section: Fig 8 Schematic Beam Path Using Two Gaussian Telescopes Fomentioning

confidence: 98%

Section: The Great/upgreat Receiversmentioning

confidence: 99%

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First Supra-THz Heterodyne Array Receivers for Astronomy With the SOFIA Observatory

Risacher

Güsten

Stützki³

et al. 2016

IEEE Trans. THz Sci. Technol.

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“…Major technological breakthroughs enabled these observations: a superconducting NbN hot-electron bolometer (HEB) waveguide mixer (Büchel et al 2015), pumped by a novel quantum-cascade laser (QCL; Richter et al 2015) as local oscillator provides receiver temperatures as low as 1000 K. The data were processed in a new-generation fast Fourier transform spectrometer (Klein et al 2012), providing a 44 kHz spectral resolution over a 2.5 GHz bandwidth.…”

Section: Observationsmentioning

confidence: 99%

First detection of the 63μm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA

Rezac

Hartogh

Güsten

et al. 2015

A&A

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Context. The Stratospheric Observatory for Infrared Astronomy (SOFIA) with its 2.5 m telescope provides new science opportunities for spectroscopic observations of planetary atmospheres in the far-infrared wavelength range. Aims. This paper presents first results from the 14 May, 2014 observing campaign of the Martian atmosphere at 4.7 THz using the German REceiver for Astronomy at Terahertz frequencies (GREAT) instrument. Methods. The atomic oxygen 63 µm transition, OI, was detected in absorption against the Mars continuum, with a high signal-to-noise ratio (∼35). A beam-averaged atomic oxygen from a global circulation model was used as input to the radiative transfer simulations of the observed line area and to obtain a new estimate on the column density using a grid-search method. Results. Minimizing differences between the calculated and observed line intensities in the least-square sense yields an atomic oxygen column density of (1.1 ± 0.2) × 10 17 cm −2 . This value is about twice as low as predicted by a modern photochemical model of Mars. The radiative transfer simulations indicate that the line forms in the upper atmospheric region over a rather extended altitude region of 70-120 km. Conclusions. For the first time, a far-infrared transition of the atomic oxygen line was detected in the atmosphere of Mars. The absorption depth provides an estimate on the column density, and this measurement provides additional means to constrain the photochemical models in global circulation models and airglow studies. The lack of other means for monitoring the atomic oxygen in the Martian upper atmosphere makes future observations with the SOFIA observatory highly desirable.

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“…For example, niobium nitride thin films are attracting rising attention in recent submillimeter and THz receiver research [1]. As an oxidation result of films of niobium or its compounds (originally homogeneous) multilayer and multiphase films are built.…”

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confidence: 99%

An XPS method for layer profiling of NbN thin films

et al. 2016

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Abstract. Layer chemical and phase profiling of niobium nitride thin films on a silicon substrate oxidized on air was performed with the help of a method designed by us. The method includes: a new method of background subtraction of multiple inelastically scattered photoelectrons considering depth inhomogeneity of electron inelastic scattering; a new method of photoelectron line decomposition into component peaks considering physical nature of different decomposition parameters; joint solution of the background subtraction and photoelectron line decomposition problems; control of line decomposition accuracy with the help of a suggested performance criterion; calculation of layer thicknesses for a multilayer target using a simple formula.The interest in thin films of niobium and its compounds is caused by their superconductive properties used in cryogenic electronic instrumentation. For example, niobium nitride thin films are attracting rising attention in recent submillimeter and THz receiver research [1]. As an oxidation result of films of niobium or its compounds (originally homogeneous) multilayer and multiphase films are built. The superconductive properties of niobium compounds become worse with increase of surface niobium oxide layer thickness. Oxide films of niobium and its compounds are covered by a great amount of works, i.e. [2][3][4][5]. However, there are no works covering layer phase profiling of oxidized thin films of niobium compounds.This work presents layer phase profiling of oxidized thin films of niobium nitride on a silicon substrate by the means of XPS. Thin niobium nitride films were sputtered onto a silicon substrate by the magnetron method. The films were oxidized during unload from the vacuum chamber. X-ray photoemission spectra were obtained with the electron-ion spectroscopy module based on the platform Nanofab 25 (NT-MDT). In the analytical chamber, an ultrahigh oil-free vacuum about 10 -8 Pa was achieved. The spectra were recorded with an electrostatic semi-spherical energy analyzer SPECS Phoibos 225.Layer profiling on the base of XPS spectra of multilayer multicomponent thin films interpretation is a complex inverse problem with a lot of unknown parameters. For correct solution of this problem new methods and approaches designed by the authors are suggested:

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4.7-THz Superconducting Hot Electron Bolometer Waveguide Mixer

Cited by 52 publications

References 28 publications

First Supra-THz Heterodyne Array Receivers for Astronomy With the SOFIA Observatory

First Supra-THz Heterodyne Array Receivers for Astronomy With the SOFIA Observatory

First detection of the 63μm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA

An XPS method for layer profiling of NbN thin films

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