Integrated terahertz quantum-cascade transceiver for high-resolution spectroscopy and space applications (iQCT)

Within the framework of the priority program INtegrated TERahErtz sySTems Enabling Novel Functionality (INTEREST) funded by the German Research Foundation (DFG), micro-integrated quantum-cascade transceivers for high-resolution spectroscopy and space applications will be developed in cooperation with the "Institute of Optical Sensor Systems" of the Deutsches Zentrum für Luft- und Raumfahrt (DLR), and the Ferdinand Braun Institute (FBH), both located in Berlin.

This project builds on the achievements of the first-phase INTEREST project ‘Micro-QCL’ which covered the development of a mechanically cooled micro-optical assembly consisting of an optimized terahertz (THz) quantum-cascade laser (QCL), optical components for optical isolation, outcoupling, as well as beam shaping, and an optical fiber. This second-phase project aims at extending this compact assembly towards a complete spectrometer transceiver, i.e., adding a quantum-cascade detector (QCD) and additional optical as well as electrical components on one compact breadboard.

The QCD, which operates by detecting infrared light through intersubband transitions in quantum wells, offers high wavelength selectivity and low noise, making it particularly suited for precise THz detection. This architecture will enhance the sensitivity of the moderately cooled detector, circumvent the vibrations of a mechanical cooler as source of noise, and improve the frequency stability.  The compact design also reduces the size and weight of the system, making it ideal for environments such as mobile platforms and space missions, where minimizing payload and power consumption is a critical requirement. Such an integrated THz transceiver will enable THz spectroscopy for astronomy, atmospheric science, biomedical studies and metrology. The miniaturized module will be developed for mobile measurements and space missions operating at frequencies of 3.5 and 4.7 THz which will enable monitoring of hydroxyl radicals and neutral atomic oxygen, respectively.