Tuesday, June 30, 2020
The first detector array for NASA’s Gusto mission has passed pre-shipment review, reports the Netherlands Institute for Space Research (SRON). The array is being shipped to the University of Arizona, where it will be integrated into the balloon observatory. The Gusto mission is to measure emissions from cosmic material between stars. SRON and Delft University of Technology are developing three 8-pixel arrays for 4.7, 1.9 and 1.4 THz. The team has now delivered its first array — for the 4.7 THz channel.
NASA’s Galactic/extragalactic ULDB Spectroscopic Terahertz Observatory (Gusto) is a balloon observatory that will drift in Earth’s atmosphere for over 75 days, at the edge of space at 36 km altitude. The launch is scheduled for December 2021 from Antarctica. The observatory consists of a telescope of one meter in diameter and three observation instruments carried by an ultra-long duration balloon (ULDB). It contains three array receivers for electromagnetic radiation of 1.4, 1.9 and 4.7 THz.
Delivering the first array is the result of an international collaboration involving SRON, TU Delft, the University of Arizona and NASA. The 4.7 THz channel is the most challenging to realize because it requires the highest sensitivity and most precise pointing of the lens-antenna beam. The design, manufacturing, assembly and testing of the array were carried out at SRON, while the superconducting detectors were developed at TU Delft.
Gusto has three channels to map respectively ionized nitrogen (NI), carbon (CII), and oxygen (OI) emission lines in the spectrum of the interstellar medium — the material floating in between stars. This helps scientists to determine the life cycle of interstellar gas in our Milky Way, witness the formation and destruction of star-forming clouds and understand the dynamics and gas flow in the vicinity of the center of our Galaxy.
Labels: Galactic/Extragalactic ULDB Spectroscopic Terahertz Observatory (GUSTO), NASA, Netherlands Institute for Space Research (SRON)
Monday, June 29, 2020
Abstract-A theoretical investigation on reciprocity-inspired wide-angle spectrally-selective THz absorbers augmented by anisotropic metamaterials
Mansoureh Mohammadi, Hamid Rajabalipanah, Ali Abdolali,
In this paper, a theoretical framework relying on the reciprocity theorem is proposed to accurately design a spectrally-selective THz superstrate-loaded metamaterial absorber (SLMA) exhibiting wide-angle feature. By leveraging high-order Floquet harmonics in a generalized transmission line model characterizing the conventional metamaterial absorbers (MAs), it is demonstrated that MAs suffer from impedance mismatch, especially at near grazing angles. From an impedance matching viewpoint, this major challenge is tackled in this paper via two different designs, exploiting a magneto-electric anisotropic Huygens' metamaterial and a multilayer dielectric structure at a certain distance over the MA plane. The numerical results corroborate well the theoretical predictions, elucidating that the proposed SLMA significantly broadens the angular performance of the MA up to near grazing angles (about 80°), where high absorptivity is still achieved in both principal planes. The deteriorating effect of diffraction modes has been comprehensively analyzed. In comparison to the previous wide-angle MA reports based on intricate particle geometries and brute-force optimizations, the proposed design features a straightforward semi-analytical algorithm, which can also be re-developed for microwave, mid-infrared, and optical frequency bands and for any type of MA element. The proposed SLMA would be very promising for various wavelength-selective applications such as sensors and imaging.
Abstract-Backward terahertz difference frequency generation via modal phase-matching in a planar LiNbO3 waveguide
B. N. Carnio and A. Y. Elezzabi
Sunday, June 28, 2020
Ruoxing Wang, Jin Han, Jianlong Liu, Hao Tian, Weimin Sun, Li Li, and Xianzhong Chen
|Schematic of the reflective THz multi-foci metalens for polarization detection. The ellipticity angle |