We demonstrate concepts for compact and cost effective THz technology based on semiconductor diode lasers. In detail,
we analyze diode laser based THz sources and detectors. Continuous wave THz radiation is generated by two color diode
lasers either with external photomixers or direct difference frequency generation in the diode laser. For time domain THz
sampling applications we present a suitable mode-locked diode laser system. Further we present a method to detect THz
radiation with diode lasers at room temperature: A THz signal coupled into the active region of a diode laser results in a
variation of the voltage across the p-n-junction.
To evaluate the potential of THz imaging systems for mail and luggage inspection we study a set of letters containing different hazardous items. The samples are investigated with three different THz systems available in our group: A microwave based system working around 100 GHz, a THz time-domain system and a THz gas laser. We provide a comparative discussion on our results and the advantages and disadvantages of each system.
We demonstrate a semi-confocal THz imaging system based on a THz gas laser operating at 2.52 THz (118 μm) with power up to tens of milliwatts. Our ultimate goal is the development of a fully confocal THz microscope. We discuss the stability of the system and present THz images obtained on different objects to illustrate the potential of the system.