Research Topics of Terahertz Sensors and Systems Group

The THz range in the electromagnetic spectrum (Fig.1) is extending from 200 GHz (0.8 meV) to 10 THz (40 meV). A lot of attractive applications in security, medicine, biology, science and non-destructive materials testing have been demonstrated already.

Ultrafast THz components based on telecom matured InP-technology are the core competence of HHI's THz group. Our photomixers and photoconductive antennas, for converting the optical signals into THz radiation and vice versa, are all operated with an optical wavelength of 1.5 µm for both, pulsed and cw techniques. Excited by femtosecond fiber lasers the pulsed systems operate up to 4 THz (Fig. 3), whereas continuous wave systems controlled by tunable DFB lasers allow highly resolved spectroscopy up to 2 THz (Fig. 4).

The THz emitter and receiver chips are packaged into fiber-coupled modules (Fig. 2), which allow the realization of flexible THz systems. Solid design and robust housing make our devices suitable for use in industrial environments.

HHI’s THz components enable system configurations according to the customer requirements and operation without specific knowledge of THz technology.

The scope of our research and development covers

  • CW THz emitters - based on ultrafast telekom photodiodes
  • Pulsed THz emitters - mesa-structured photoconductors
  • Photoconductive THz receivers - for serving both pulsed and cw systems
  • Assembly and test of complete fibre coupled THz systems
  • Application studies and consulting
Fig. 1: The electromagnetic spectrum
Fig. 2: HHI's fibre coupled THz emitter / receiver module
Fig. 3: Water vapor absorption spectrum recorded with our pulsed THz System in comparison with the HTRAN database (offset for clarity)
Fig.4: High resolution water vapor absorption spectrum recorded with our cw THz System
Fraunhofer HHI's TeraWave TDS system demonstrator