Part of the experimental setup for laser-based vector network analysis. A cluster of planar waveguides has been fabricated on a semiconductor. The waveguides are contacted at either end using two microwave probes. A laser beam is focused from the front onto the waveguide and generates in a photoconductive gap ultrashort voltage pulses. The voltage pulses are detected by a second laser beam which is focused from the back through the substrate onto the planar waveguide. Credit: PTB
by Erika Schowhttp://phys.org/news/2015-11-vector-network-analysis-lasers.html#jCp
Vector network analyzers (VNA) are among the most precise high-frequency measurement devices available today. Due to continuous development within the last decades VNAs are usable up to frequencies of 1 terahertz (1012 Hz) and complex error correction algorithms exist. However, VNAs are very expensive and require multiple frequency extenders in order to cover a wide frequency range. At the Physikalisch-Technische Bundesanstalt (PTB) a VNA has been developed which utilizes optoelectronic techniques based on femtosecond lasers. Such devices constitute a cost-effective alternative to conventional VNAs and might be used for high-frequency measurements in the future. The results have been published in the present issue of the renowned journal IEEE Transactions on Microwave Theory and Techniques.