Conclusion and outlook
Terahertz spectroscopy

Mastering the manipulation of THz radiation during propagation is a fundamental field of study for the development of future communication systems. Of particular interest is the transfer of information from the optical band to the THz band – opto-THz modulation –. For example, the control of THz propagation via optical pulses. A functional device of this kind – opto-THz modulator – should consist of an active element capable of modifying its THz properties following optical illumination (an ultrafast semiconductor, for example, as we have seen in the previous paragraphs) and a resonant structure designed to amplify the interaction between the optical and THz beams in the active element (in order to optimize the energy cost of modulation). The design and characterization of such devices can be interviewed within the framework of the – THz probe optical pump scheme for dynamic response, and...