A 1.3-THz Balanced Waveguide HEB Mixer for the APEX Telescope

Meledin, Denis; Pavolotsky, Alexey; Desmaris, Vincent; Lapkin, Igor; Risacher, C.; Pérez, Valentín Viqueira; Henke, Doug; Nyström, Olle; Sundin, Erik; Dochev, D; Pantaleev, Miroslav; Fredrixon, Mathias; Strandberg, Magnus; Voronov, B.; Gol’tsman, G.; Belitsky, Victor

doi:10.1109/tmtt.2008.2008946

Cited by 86 publications

(61 citation statements)

References 29 publications

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“…We expect that this effect should significantly decrease the sensitivity of receivers employing HEB mixers, e.g. for frequencies above 1.4 THz where these devices are the heterodyne mixers of choice and where only few balanced mixers were realized to date 29,30 .…”

Section: Discussionmentioning

confidence: 99%

A 490 GHz planar circuit balanced Nb-Al2O3-Nb quasiparticle mixer for radio astronomy: Application to quantitative local oscillator noise determination

Westig

Justen

Jacobs

et al. 2012

Journal of Applied Physics

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This article presents a heterodyne experiment which uses a 380-520 GHz planar circuit balanced Nb-Al 2 O 3 -Nb superconductor-insulator-superconductor (SIS) quasiparticle mixer with 4-8 GHz instantaneous intermediate frequency (IF) bandwidth to quantitatively determine local oscillator (LO) noise. A balanced mixer is a unique tool to separate noise at the mixer's LO port from other noise sources. This is not possible in singleended mixers. The antisymmetric IV characteristic of a SIS mixer further helps to simplify the measurements. The double-sideband receiver sensitivity of the balanced mixer is 2-4 times the quantum noise limit hν/k B over the measured frequencies with a maximum LO noise rejection of 15 dB. This work presents independent measurements with three different LO sources that produce the reference frequency but also an amount of near-carrier noise power which is quantified in the experiment as a function of the LO and IF frequency in terms of an equivalent noise temperature T LO . Two types of LO sources are used: a synthesizer driven amplifier/multiplier chain and a Gunn oscillator driven multiplier chain. With the first type of LO we find different near-carrier noise contributions using two different power pre-amplifiers of the LO system. For one of the two power pre-amplifiers we measure T LO = 30 ± 4 K at the LO frequency 380 GHz and T LO = 38 ± 10 K at 420 GHz. At the frequency band center 465 GHz of the Gunn driven LO we measure a comparable value of T LO = 32 ± 6 K. For the second power pre-amplifier a significant higher T LO value of the synthesizer driven LO is found which is up to six times larger compared with the best values found for the Gunn driven LO. In a second experiment we use only one of two SIS mixers of the balanced mixer chip in order to verify the influence of near-carrier LO noise power on a single-ended heterodyne mixer measurement. We find an IF frequency dependence of near-carrier LO noise power. The frequency-resolved IF noise temperature slope is flat or slightly negative for the single-ended mixer. This is in contrast to the IF slope of the balanced mixer itself which is positive due to the expected IF roll-off of the mixer. This indicates a higher noise level closer to the LO's carrier frequency. Our findings imply that near-carrier LO noise has the largest impact on the sensitivity of a receiver system which uses mixers with a low IF band, for example superconducting hot-electron bolometer (HEB) mixers.

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Section: Discussionmentioning

confidence: 99%

A 490 GHz planar circuit balanced Nb-Al2O3-Nb quasiparticle mixer for radio astronomy: Application to quantitative local oscillator noise determination

Westig

Justen

Jacobs

et al. 2012

Journal of Applied Physics

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“…The group of advanced receiver development of Chalmers University of Technology developed a balance waveguide HEB mixer for the 1.25-1.39 THz band [33]. The mixer mount block consists of two NbN HEB mixer chips and a waveguide 3-dB 90…”

Section: Mixer Mount Designmentioning

confidence: 99%

Application of Superconducting Hot-Electron Bolometer Mixers for Terahertz-Band Astronomy

Maezawa

2015

IEICE Trans. Electron.

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SUMMARY Recently, a next-generation heterodyne mixer detectora hot electron bolometer (HEB) mixer employing a superconducting microbridge-has gradually opened up terahertz-band astronomy. The surrounding state-of-the-art technologies including fabrication processes, 4 K cryostats, cryogenic low-noise amplifiers, local oscillator sources, micromachining techniques, and spectrometers, as well as the HEB mixers, have played a valuable role in the development of super-low-noise heterodyne spectroscopy systems for the terahertz band. The current developmental status of terahertz-band HEB mixer receivers and their applications for spectroscopy and astronomy with ground-based, airborne, and satellite telescopes are presented.

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“…Therefore, we suggest the use of GaN as the material for thin membranes, which has proven to be mechanically robust, inert to most chemicals, and allow for the growth of heterostructure and epitaxial nitrides [11,12]. Furthermore, it has recently been demonstrated that GaN serves also as an excellent buffer-layer for the epitaxial growth of NbN superconducting nanofilms [13,14], which are used in the most sensitive heterodyne receivers above 1.2 THz based on NbN HEB mixers for radio astronomical spectroscopy [15,16]. Alternative buffer-layers or substrates that yield single crystal NbN films are MgO [17,18], SiC [19,20] and sapphire [21], however, the use of sapphire in waveguide applications is restricted due to its hardness and MgO as a thin buffer-layer on Si or lapped quartz substrates is hygroscopic and may lead to life-time issues in the active device.…”

Section: Introductionmentioning

confidence: 99%

Suspended GaN beams and membranes on Si as a platform for waveguide-based THz applications

Krause

Desmaris

Pavolotsky

et al. 2018

J. Micromech. Microeng.

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Epitaxial growth of ultra-thin NbN films on AlxGa1-xN buffer-layers S Krause, D Meledin, V Desmaris et al. IntroductionThe exploration of the THz frequency range is constantly gaining speed and numerous applications have emerged within research, security, astronomy, biomedicine and metrology in recent years [1][2][3]. The main reason for this relatively late development can be attributed to several technological challenges that had to be overcome. As the dimensions of microwave components usually scale with the wavelength, their size presents a serious issue when the device operation frequency is approaching the THz range. This manifests itself in certain performance limitations due to parasitic capacitances, thermal issues, the excitation of unwanted electromagnetic (EM) modes or excessive RF losses in conductors as the skin depth may approach the roughness of the metal surface. Waveguides for guiding THz EM waves offer wideband operation and full confinement of the fields, yet they are also miniaturized and demand high surface quality and accuracy on the waveguide dimensions and alignment. Several different micro fabrication techniques [4] were developed for this purpose and are based on copper electroforming over a thick sacrificial photo resist mold [5,6] or deep Si etching processes [7]. In waveguidebased THz components, the actual substrate becomes more of a delicate membrane-like structure, which reduces the electrical loading of the waveguide and excludes substrate modes. However, it is difficult to manipulate and to place such beams suspended inside the waveguide with high alignment precision. Typically beam leads [8] made of thick electro-plated gold are used for the electrical contacting, however, once the device is mounted it can neither be modified nor removed in a non-destructive matter. One possible approach to overcome the aforementioned issues is based on a Π-shaped Si support frame holder [9], which keeps a thin Si membrane hosting the active device suspended. This concept has been successfully AbstractWe demonstrate the suitability of employing suspended GaN beams on a Π-shaped Si frame for waveguide-based cryogenic THz components and systems. This concept addresses major challenges and provides eased device handling, cryogenic operation, micron-alignment possibilities, high integratability and allows the electrical contacting by using bonding wires. In particular, a balanced hot electron bolometer (HEB) mixer was implemented for frequencies at 1.3 THz with state-of-the-art IF performance, which combines micro-machined all-metal waveguide components in conjunction with a suspended GaN beam. In addition, in order to accomplish a proper design of active or passive components, the accurate knowledge of the effective dielectric constant at THz frequencies is crucial when such membranes are employed. Thus, a direct measurement method based on a resonance structure and an S-parameter measurement between 1 THz and 1.5 THz is also presented.Keywords: THz components, GaN on Si, HEB, waveguide (Some f...

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A 1.3-THz Balanced Waveguide HEB Mixer for the APEX Telescope

Cited by 86 publications

References 29 publications

A 490 GHz planar circuit balanced Nb-Al2O3-Nb quasiparticle mixer for radio astronomy: Application to quantitative local oscillator noise determination

A 490 GHz planar circuit balanced Nb-Al2O3-Nb quasiparticle mixer for radio astronomy: Application to quantitative local oscillator noise determination

Application of Superconducting Hot-Electron Bolometer Mixers for Terahertz-Band Astronomy

Suspended GaN beams and membranes on Si as a platform for waveguide-based THz applications

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