Olivier Auriacombe | Searcharxiv

arXiv2026

Compact Dual-Polarization Schottky Barrier Diode Receivers for Submillimeter Wave Remote Sensing

Dual-polarization heterodyne receivers operating at 325 GHz, 424 GHz, and 650 GHz at room temperature are presented. Polarimetric measurements are enabled by two orthogonal open-ended E-field probes, co-optimized and integrated with two subharmonic GaAs Schottky-barrier diode mixers. The down-converted signals (IF) are amplified using low-noise InP HEMT amplifiers integrated into the receiver module, along with IF matching networks, dc-bias boards, a shared local oscillator (LO) distribution network, and a single smooth-walled, conical, spline-horn antenna. Maximum cross-polarization isolation of 25 dB, 34 dB, and 25 dB was achieved at 315 GHz, 421 GHz, and 650 GHz, respectively. The measured double-sideband (DSB) receiver noise temperatures are 833 K, 835 K, and 1623 K at 315 GHz, 421 GHz, and 630 GHz, respectively. Stability measurements, with an integration Allan time of more than 10 s, were obtained for all receivers. Overall, the integrated dualpolarization receiver topology achieves excellent sensitivity in a highly compact package, offering an efficient and scalable solution for polarimetric applications in submillimeter-wave remote sensing

physics.ins-det↗

arXiv2021

The Role of Terahertz and Far-IR Spectroscopy in Understanding the Formation and Evolution of Interstellar Prebiotic Molecules

Stellar systems are often formed through the collapse of dense molecular clouds which, in turn, return copious amounts of atomic and molecular material to the interstellar medium. An in-depth understanding of chemical evolution during this cyclic interaction between the stars and the interstellar medium is at the heart of astrochemistry. Systematic chemical composition changes as interstellar clouds evolve from the diffuse stage to dense, quiescent molecular clouds to star-forming regions and proto-planetary disks further enrich the molecular diversity leading to the evolution of ever more complex molecules. In particular, the icy mantles formed on interstellar dust grains and their irradiation are thought to be the origin of many of the observed molecules, including those that are deemed to be prebiotic; that is those molecules necessary for the origin of life. This review will discuss both observational (e.g., ALMA, SOFIA, Herschel) and laboratory investigations using millimeter, submillimeter, and terahertz and far-IR (THz/F-IR) spectroscopies and the role that they play in contributing to our understanding of the formation of prebiotic molecules. Mid-IR spectroscopy has typically been the primary tool used in laboratory studies. However, THz/F-IR spectroscopy offers an additional and complementary approach in that it provides the ability to investigate intermolecular interactions compared to the intramolecular modes available in the mid-IR. THz/F-IR spectroscopy is still somewhat under-utilized, but with the additional capability it brings, its popularity is likely to significantly increase in the near future. This review will discuss the strengths and limitations of such methods, and will also provide some suggestions on future research areas that should be pursued in the coming decade exploiting both space-borne and laboratory facilities.

astro-ph.GA↗