A Tunable Unidirectional Source for GUSTO’s Local Oscillator at 4.74 THz

Gal/Xgal U/LDB Spectroscopic/ Stratospheric THz Observatory (GUSTO) is a NASA Explorers Mission of Opportunity that will make large scale maps of the Milky Way and Large Magellanic Cloud in three important interstellar lines:[CII], [OI], and [NII] at 158, 63, and 205 µm, respectively. During its ~75 day stratospheric (~36 km) flight, GUSTO's 0.9-meter balloon-borne telescope and THz heterodyne array receivers will provide the spectral and spatial resolution needed to untangle the complexities of the interstellar medium by probing all phases of its Life Cycle. The GUSTO payload consists of (1) a telescope; (2) three 8-pixel heterodyne array receivers; (3) autocorrelator spectrometers; (4) instrument control electronics; and (5) a cryostat. The GUSTO gondola is derived from successful APL designs. Much of the GUSTO instrument architecture and hardware is based on the experience gained in developing and flying the Stratospheric Terahertz Observatory (STO). GUSTO is currently undergoing integration and test and will launch from the NASA Long Duration Balloon (LDB) Facility near McMurdo, Antarctica in December 2023.

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“…The waveguide design [5], which is the most advanced terahertz QCL for the purpose of LOs (see Fig. 6).…”

Section: Local Oscillatorsmentioning

confidence: 99%

Gal/Xgal U/LDB Spectroscopic/Stratospheric THz Observatory: GUSTO

Walker¹,

Kulesa²,

Young³

et al. 2022

Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI

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“…At 10 K, the cw output power amounted to 1.0 mW using P pump ≈ 1.6 W with a 3 GHz tuning range. Khalatpour et al [23,24] reported on an array of 18 unidirectional antenna-coupled third-order distributed-feedback QCLs for the local oscillator at 4.745 THz of the Galactic/Extra Ultra-Long-Duration Balloon Spectroscopic-Stratospheric Terahertz Observatory (GUSTO), which is based on a unidirectional wire laser. At 55 K, the cw output power of one QCL in the array amounted to more than 8 mW using P pump ≈ 2.2 W with a 6 GHz tuning range.…”

Section: Introductionmentioning

confidence: 99%

Terahertz quantum-cascade lasers for high-resolution absorption spectroscopy of atoms and ions in plasmas

Röben

Biermann

et al. 2023

Semicond. Sci. Technol.

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We report on terahertz (THz) quantum-cascade lasers (QCLs) based on GaAs/AlAs heterostructures, which exhibit single-mode emission at 3.360, 3.921, and 4.745 THz. These frequencies are in close correspondence to fine-structure transitions of Al atoms, N+ ions, and O atoms, respectively. Due to the low electrical pump power of these THz QCLs, they can be operated in a mechanical cryocooler in continuous-wave mode, while a sufficient intrinsic tuning range of more than 5 GHz is maintained. The single-mode operation and the intrinsic tuning range of these THz QCLs allow for the application of these lasers as radiation sources for high-resolution absorption spectroscopy to determine the absolute densities of Al atoms, N+ ions, and O atoms in plasmas.

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“…To this end, since the spectral lines are well defined, a heterodyne measurement setup can be used, where the incoming signal is mixed with a local oscillator of precisely controlled frequency. Terahertz quantum cascade lasers (QCL) [8], [9] are prime candidates for such a role, given their frequency span, compactness and high achievable output power [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], for both ground based and airborne [20], [21], [22], [23] laboratories, while significant progress is also being done towards their high temperature operation [24], [25], [26].…”

Section: Introductionmentioning

confidence: 99%