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The Heterodyne Receiver for Origins (HERO) is the first detailed study of a heterodyne focal plane array receiver for space applications. HERO gives the Origins Space Telescope the capability to observe at very high spectral resolution (R = 107) over an unprecedentedly large far-infrared (FIR) wavelengths range (111 to 617 μm) with high sensitivity, with simultaneous dual polarization and dual-frequency band operation. The design is based on prior successful heterodyne receivers, such as Heterodyne Instrument for the Far-Infrared /Herschel, but surpasses it by one to two orders of magnitude by exploiting the latest technological developments. Innovative components are used to keep the required satellite resources low and thus allowing for the first time a convincing design of a large format heterodyne array receiver for space. HERO on Origins is a unique tool to explore the FIR universe and extends the enormous potential of submillimeter astronomical spectroscopy into new areas of astronomical research.

We report on the demonstration of an ultra-high-sensitivity superconducting hot-electron-bolometer (HEB) heterodyne receiver at 2.5 THz with a low-power-consumption quantum cascade laser (QCL) as its local oscillator (LO). The 2.5-THz QCL, with an electrical power dissipation of about 0.9 W in continuous wave mode, is integrated with a spiral-antenna-coupled niobium nitride HEB mixer in a single block. The mixer performance is barely affected by heat dissipation from the QCL when the receiver is cryogenically cooled either by a wet LHe Dewar or by a closed-cycle 4-K pulse-tube cooler. Measured with a vacuum setup, the heterodyne receiver exhibits a double sideband receiver noise temperature of 800 K at 2.5 THz with the IR filter contribution corrected, which is approximately 7hυ/kB. And the Allan variance time at 80-MHz noise bandwidth is found to be about 10 s when a proportional-integral-derivative controller is adopted to control the LO power.

Quasi-optical superconducting hot-electron bolometer (HEB) mixers have shown a competitive sensitivity at a frequency slightly lower than 1 THz when compared to superconducting SIS mixers. The advantage of low LO power requirement makes superconducting HEB mixers, especially suitable for array application. The far-field beam pattern, as well as coupling efficiency of quasi-optical superconducting HEB mixers, depends strongly upon the lens shape and the dielectric constant of the lens material. Therefore, in this letter we precisely measured the dielectric constant and loss tangent of high resistivity silicon at 4, 77, and 300 K in the frequency range of 700–900 GHz where many important molecular lines located. The measurements are performed by employing a quasi-optical vector network analyzer with a dynamic range as high as 110 dB to ensure high precision measurement. In addition, the dielectric constant of high-density polyethylene (HDPE) and polymethylpentene (TPX/PMP) are also measured since they are widely used in terahertz quasi-optical system.

A 2 x 2 local oscillator beam divider for pumping a hot electron bolometer mixer array is designed at 1370 GHz. Traditional rectangular waveguide based H-plane and E-plane junctions are used to construct the feeding network. Two 400-μm thick silicon wafers are used to build the feeding network, and an aluminum plate is used to build the circular horn array. Multilayer micromachining and multilayer stack assembling are the two key technologies employed in building this beam divider.

In this paper, the performance of a twin-slot antenna coupled NbN superconducting HEB mixer based on a new device fabrication process is thoroughly investigated. The measured lowest double-sideband receiver noise temperature is about 600 K at 1.3 THz, and reduced to 300 K after eliminating all the quasi-optical losses. The spectral response of the HEB mixer is characterized by a Fourier Transform Spectrometer (FTS) and its calibrated spectrum is in good agreement with the simulated one. In addition, the far-field beam pattern of this HEB mixer is characterized by a near-field measurement technique. The measured results agree well with the simulations too.

The performance of a 1.3 THz twin-slot antenna coupled superconducting hot-electron-bolometer (HEB) mixer integrated with elliptical lenses of different extension lengths are investigated. The elliptical lenses have the same radius but different extension lengths: 1.109 mm, 1.149 mm, 1.189 mm and 1.229 mm. The measured noise temperature and frequency response appears insensitive to the lens extension length. The far-field beam-patterns, directivity and Gaussicity are clearly related to the lens extension length.

In this paper, we report on the measured and simulated far-field beam-patterns of a quasi-optical NbN superconducting hot electron bolometer (HEB) mixer at 600GHz. This superconducting HEB mixer consists of an extended hemispherical lens with a diameter of 12.7mm and an extension length of 2.45mm, a twin-slot planar antenna (two slots measuring 148.5μm × 10.4μm with a separation of 78.98μm) and a 5.5-nm thick NbN thin-film micro-bridge with an area of 2μm × 0.2μm . The far-field beam pattern of this mixer is measured by a direct-detection technique with a dynamic range of nearly 25dB, showing an FWHM beam angle of 2.7° and -18dB level of the first side-lobe. The measured beam of the quasi-optical mixer is nearly collimated and has good Gaussian beam efficiency. In addition, the far-field beam-pattern is measured at different DC bias voltages of the superconducting HEB mixer and at different bath temperatures. The measured results are compared with the ones simulated by two different methods. Detailed measurement and simulation results will be presented.

International audience; Various buffer layers have been investigated in order to improve the crystalline quality of NbN ultra-thin films. The structural properties, the thickness, the surface morphology of 5-10 nm NbN films have been studied by different techniques. Uncertainty on thickness measurements in this range and the relation between NbN film quality and gain bandwidth are discussed in the framework of their use in Hot Electron Bolometers (HEB).

A 16 pixel heterodyne receiver for 2.5 THz has been developed based on NbN superconducting hot-electron bolometer (HEB) mixers. The receiver uses a quasioptical RF coupling approach where HEB mixers are integrated into double dipole antennas on 1.5μm thick Si 3 N 4 /SiO 2 membranes. Spherical mirrors (one per pixel) and backshort distance from the antenna have been used to design the output mixer beam profile. The camera design allows all 16 pixel IF readout in parallel. The gain bandwidth of the HEB mixers on Si 3 N 4 /SiO 2 membranes was found to be 0.7÷0.9 GHz, which is much smaller than for similar devices on silicon. Application of buffer layers and use of alternative types of membranes (e.g. silicon-on-insulator) is under investigation.

We present in this paper the front-end design and the results of RF simulations, carried out with Microwave Studio (CST) and HFSS for SHAHIRA (Submillimeter Heterodyne Array for High-speed Radio Astronomy), a 4x4 heterodyne array at 2.5 THz and 4.7 THz. One can then observe 16 spatial positions at 2 frequencies. The design has been chosen to be quasi-optic, because of its simplicity, novelty and multi-pixels applicability. Pixels are made of Niobium Nitride HEB mixers with double-slot antennas, processed on 1 μm thick stress-less Si3N4/SiO2 membrane. The use of the membrane shows numerous advantages: for instance the use of the mixers at higher RF frequencies, a better power coupling efficiency or a solution for avoiding dielectric modes, losses and reflections. This work is supported by ESA and is a collaboration between LERMA, CHALMERS and LAAS. The Camera is expected to find applications, for SOFIA or CIDRE.

Observation and analysis of submillimeter-wave radiation (300GHz-3THz) in astronomy and atmospheric sciences requires increasingly performant receivers. The most sensitive receivers working in this range of electromagnetic spectrum use superconductor-insolator-superconductor (SIS) junctions. In order to increase the bandwidth and the sensitivity, we are developing a quantum-noise limited heterodyne receiver based on several parallel SIS junctions with broad (larger than 30%) fixed tuned bandwidth. These circuits can be viewed as passband filters which have been optimized by varying the spacings between junctions. We have designed such 5-junction arrays for operation in the range 480-640 GHz. Fabrication and heterodyne characterization of these devices has been done. The 1 μm2 junctions current density ranges from 4 to 13 kA/cm2, using optical lithography and Nb/Al2Nb5/Nb trilayer sputtering technology. The fabrication process and yield are presented in this paper, along with measured performances© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We report in this paper a new concept for 2.7 THz superconducting Niobium nitride (NbN) Hot-Electron Bolometer mixer (HEB). The membrane process was developped for space telecommnunication applications a few years ago and the HEB mixer concept is now considered as the best choice for low-noise submillimeter-wave frequency heterodyne receivers. The idea is then to join these two technologies. The novel fabrication scheme is to fabricate a NbN HEB mixer on a 1 μm thick stress-less Si 3 N 4 /SiO 2 membrane. This seems to present numerous improvements concerning : use at higher RF frequencies, power coupling efficiency, HEB mixer sensitivity, noise temperature, and space applications. This work is to be continued within the framework of an ESA TRP project, a 2.7 THz heterodyne camera with numerous applications including a SOFIA airborne receiver. This paper presents the whole fabrication process, the validation tests and preliminary results. Membrane-based HEB mixer theory is currently being investigated and further tests such as heterodyne and Fourier transform spectrometry measurement are planed shortly.

We report on the status of the development of a 30% bandwidth tunerless SIS double-sideband mixer for the “Band 1” (480 GHz-630 GHz) channel of the heterodyne instrument (HIFI) of ESA’s Herschel Space Observatory, scheduled for launch in 2007. After exposing the main features of our mixer design, we present the performance achieved by the demonstration mixer, measured via Fourier Transform Spectroscopy and heterodyne Y factor calibrations. We infer from a preliminary mixer analysis that the mixer has very low, quantum-limited noise and low conversion loss. We also report on some pre-qualification tests, as we currently start to manufacture the qualification models and design the last iteration of masks for SIS junction production.