THz Synthesis and Interaction - Project 02

Project leader: Karl Unterrainer

The region of the electromagnetic spectrum between visible (infrared) photonics and high frequency electronics is called the Terahertz range. It can be defined from 0.3 to 30 THz (1 mm – 10 μm wavelength) and is a frontier research area.

In this project part we will search for novel THz sources and investigate THz light matter interaction. We will study THz sources based on intersubband transitions with new cavity designs (photonics crystal cavities), coupling between cavities, and strong cavity – intersubband coupling. We will also use femtosecond laser pulses to generate few cycle using elementary excitation in solids with non-linear frequency mixing.

The development of more intensive femtosecond laser pulses in the SFB is a requirement for the generation of high-intensity THz transients. With these high-intensity pulses we will be able to enter the strong THz field physics by studying intersubband transitions. A unique aspect is that we will employ a new phase-resolved THz time domain method. This allows to study all strong field effects phase resolved i.e. we will be able to control the phase of the driving pulses as well as to detect the phase of the response. From these experiments we will gain new insight into the fundamentals of non-linear interaction and into the dephasing and scattering processes of nanostructures. The later will be very usefull for the understanding of intersubband THz sources. In particular, for the cavities investigated strong confinement is expected which increases the coupling between THz radiation and intersubband transitions. Thus, the timeresolved study of these cavities is a further important goal within this project part.

The long term goal is to be able to combine the advantages of THz emission from intersubband transitions with the phase-control of femto-second laser pulse generated THz pulses.







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