(IMAGE) Physikalisch-Technische Bundesanstalt (PTB) Caption 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 (Photo: PTB) Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.