Each mobile telecommunications network requires synchronization between its components. Deutsche Telekom Technik AG has decided to test a method developed by the AGH University of Science and Technology in Krakow, Poland, for the future monitoring of selected points in its network. It is based on optical time transmission (OTT), which has been tested in cooperation with PTB, among others on glass fiber links of Deutsche Telekom AG (DTAG). The results exceed by far the requirements of the International Telecommunication Union (ITU-T) for 5G networks.

For the analysis of measured data in spectroscopic Mueller matrix ellipsometry (MME) there exist some commonly used optimization techniques to calculate for example layer thicknesses of samples under test. Concentrating on metrological aspects of MME we identified a non-optimal treatment of depolarization in all these techniques. Therefore, we recently developed an improved optimization method to take depolarization in MME adequately into account. In a further step we also included statistical measurement noise and derived a likelihood function, which enabled us to apply both the maximum likelihood method and Bayesian statistics as well as the Bayesian information criterion for the data evaluation. In this paper we concentrate on the application of this new method for measurements of SiO2-layer thicknesses on silicon. With a state-of-the-art SENTECH SENresearch 4.0 Mueller ellipsometer we measured different SiO2-layer thickness standard...

We demonstrate the retrieval of deep subwavelength structural information in nano-optical polarizers by scatterometry of quasi-bound states in the continuum (quasi-BICs). To this end, we investigate titanium dioxide wire grid polarizers for application wavelengths in the deep ultraviolet (DUV) spectral range fabricated with a self-aligned double-patterning process. In contrast to the time-consuming and elaborate measurement techniques like scanning electron microscopy, asymmetry induced quasi-BICs occurring in the near ultraviolet and visible spectral range provide an easily accessible and efficient probe mechanism. Thereby, dimensional parameters are retrieved with uncertainties in the sub-nanometer range. Our results show that BICs are a promising tool for process control in optics and semiconductor technology.