Search

Quantum cascade (QC) structures, for both emitting and detecting mid-infrared radiation, are powerful devices for spectroscopy. QC lasers (QCLs), which have been built for nearly 15 years, already play the leading role in certain wavelength regions. QC detectors (QCDs) are a fairly new development, which has been evolving from the QCL research. In high-resolution heterodyne spectrometers for astronomy, such as the Cologne tuneable heterodyne infrared spectrometer (THIS), QC devices help to open new windows to space as discussed in this paper. We will briefly review the use of QC devices in THIS, show recent results in measuring planetary atmospheric dynamics and give an outlook to astronomical goals for the future. [ABSTRACT FROM AUTHOR]

We report Second Harmonic Generation (SHG) and Third Harmonic Generation (THG) energy conversion efficiencies up to 59% and 27%, respectively, for laser pulses simultaneously delivering high peak power in the sub-TW range and average powers in the sub-kW range. No damage or efficiency decrease is observed after more than 100 h operation time. The resulting high-energy visible and near-UV pulses are suitable for applications, such as lightning control, material analysis and machining, or OPCPA pumping. [ABSTRACT FROM AUTHOR]

Abstract: High-resolution spectroscopy is a versatile tool to study planetary atmospheres. In the mid infrared wavelength regime the highest possible spectral resolution is provided by applying heterodyne techniques. At spectral resolution of more than observations of fully resolved molecular features are possible allowing retrieval of many physical parameters from single lines. In addition, due to the fact that many of the observed species are abundant also in the Earth''s atmosphere, high-resolution measurements allow to peak through the telluric features and lead to less ambiguity than low-resolution data. The paper will present a detailed description of the Cologne-based receiver THIS, the only tuneable heterodyne infrared spectrometer for application to astronomy offering access to the 7– wavelength region at a resolution of up to and a bandwidth of 3GHz. An overview of the science addressable with THIS will be given as well as a brief introduction to the theory of heterodyning in the infrared including a comparison to direct detection instrumentation. [Copyright &y& Elsevier]

Abstract: During 2003, a camera designed to measure the optical pulsations of pulsars was installed on a telescope of the H.E.S.S. array. The array is designed for γ-ray astronomy in the ∼100GeV–100TeV energy regime. The aims of this exercise were two-fold: to prove the pulsar timing capabilities of H.E.S.S. on all relevant time-scales, and to explore the possibility of performing sensitive optical pulsar measurements using the ∼100m2 mirror of a Cherenkov telescope. Measurements of the Crab pulsar with this instrument demonstrate an order of magnitude sensitivity improvement over previous attempts using Cherenkov telescopes. Here we describe the design and performance of the system and discuss design considerations for future instruments of this type. [Copyright &y& Elsevier]