Terahertz dynamics in semiconductor quantum structures

The Terahertz part of the electromagnetic spectrum defines a gap in solid state technology. This is most apparent if one focuses on sources. In this presentation we review experiments with the UCSB free-electron laser that have revealed the rich phenomena related to photon assisted transport in semiconductor quantum transport devices and the use of quasi-optical arrays and waveguide structures to measure Terahertz admittance of electrically biased devices.