Selected photonic THz technologies

The THz spectral range is yet not fully exploited to its full potential due to the current limitations in sources and detectors. To open the frequency range for applications, photonic solutions have been at the technological forefront. For example the advances of time domain spectroscopy techniques using short pulse lasers have enabled provision of full spectroscopy data across the range. There are different types of systems and their development should be driven by the requirements of the potential application. Photonic techniques are desirable solutions for millimeter and THz generation in terms of their energy efficiency, bandwidth, and, above all, their tuning range. Recent developments in this area target the improvement of optical-to-THz converters as well as pushing the level of integration of semiconductor laser sources in order to address the main drawbacks, cost and spectral purity. The purpose of this chapter is to describe the main types of photonically enabled THz systems and the expected performances from their components. Then a description of the key elements in designing each of the components and their limitation is given. The final part of the chapter is a discussion on potential future development and the importance of integration.