THz-Mikroskopie von Mikrowellenbauelementen und optischen Terahertz-Komponenten
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Beschreibung
A THz microscope is used for three-dimensional imaging in the frequency range from about 1 GHz to 5 THz. Josephson cantilevers are employed as sensors, which are fabricated from the high-temperature superconductor YBa2Cu3O7 on LaAlO3 or MgO bicrystal substrates. The working principle of the Josephson cantilever is based on the use of a Josephson junction. The junction can additionally be equipped with different types of antennas. It enables the investigation of high-frequency radiation in terms of both power and frequency. At the same time, temperatures and magnetic fields can also be measured with the Josephson cantilever.
In this work, a new THz microscope was set up and put into operation at the LENA research center. The system comprises an evacuable measuring chamber with Mu-metal shielding. A three-axis positioning system for the sensor as well as a two-axis sample positioning system were installed in this vacuum chamber. Two separate cryo systems can be used for cooling the sensor and the sample. Furthermore, there is a contact detection system with which height profiles can also be recorded. As a powerful THz-radiation source, an optical pumped far-infrared laser system was used to generate frequencies up to 2.52 THz with powers greater than 100 mW. A scanning beam profiler and an interferometer were developed to study the laser beam in terms of field distribution and frequency.
The control of the THz microscope has been automated were this was possible and is controlled by a single program that is connected to all components and peripheral devices of the THz microscope. In addition, a smartphone application is available, which allows monitoring of the most important system parameters.
When using the THz microscope to investigate high-frequency radiation, a distinction can be made between two main frequency ranges. In the microwave frequency range, a microstrip line was investigated to evaluate the system. In the terahertz frequency range, measurements were carried out with the far-infrared laser system. On the one hand, the mode pattern was measured. Here, not only statements on the general field distribution can be made, but also frequency components in the laser beam can be distinguished. On the other hand, additively manufactured spiral phase plates were used to generate terahertz twisted light, the mode pattern was measured and the orbital angular momentum was detected with the aid of the THz microscope. In addition, diffraction patterns of reflective diffraction gratings were recorded.
Autor*in
Meinhard Schilling
Themen in »THz-Mikroskopie von Mikrowellenbauelementen und optischen Terahertz-Komponenten«
Hochfrequenzstrahlung Mikrowellenbereich Kryosystem Terahertzbereich dreidimensionale Bildgebung Vakuum Smartphone-Applikation THz-Mikroskop supraleitender Sensor Laserstrahl Josephson-Cantilever Sensor Vakuumkammer Feldverteilung Frequenzkomponenten Terahertz Twisted- Light