Among the wide range of applications in the THz range such as imaging, security, short-range broadband communications and biomedical imaging and diagnostics, we focus our work on the development of a THz source as a local oscillator (LO) for radio astronomical heterodyne receivers.
In Radio Astronomy, receiving systems are sensitive to a given polarization mode. Splitting the incoming electromagnetic radiation into these modes allows simultaneous multicolor-imaging or spectroscopy in different frequency windows. The required devices - i.e., wire-grids reflecting one plane of polarization and transmitting the orthogonal one - are manufactured in the Terahertz Technology Division. They are also used to improve the sensitivity of our receivers, to inject local oscillator signals, or to perform polarization-sensitive observations tracing cosmic magnetic fields. A recent promising development in this field is the use of dichroic filters, made of custom-tailored metamaterials.
The signals measured in Submillimeter Radio Astronomy can only be transported and amplified after a down-conversion to lower frequencies. In the underlying heterodyne mixing process, the original signal is superposed with that emitted by a slightly detuned, local oscillator. This creates a beating at an intermediate frequency (IF) but preserves the spectroscopic characteristics of the original signal (e.g., the width and profile of a spectral line). The obtained signal needs to be transported to the digital spectrometers analyzing the signal further and be adapted to their input parameters (e.g. frequency bandwidth, input power level). The required devices are designed and manufactured in our division.