THz Radiation

THz Radiation

At present, what hinders the exploitation of THz is that generating this radiation at any meaningful power level presents many practical hurdles. Commercial systems use expensive femtosecond lasers as sources with cost in excess of 100k€, with no cheap and practical THz systems available. In addition, these expensive systems are single pixel systems with output powers of μWatts which require to be mechanically rastered, thereby taking 10s of minutes to hours to undertake complete images.

By addressing significant material science challenges with innovative experimental & theoretical approaches, FLASH aims to develop a cheap and compact THz quantum-cascade laser (QCL) integrated on Si using complementary-metal-oxide-semiconductor (CMOS)-compatible processes and materials. QCLs are unipolar intersubband lasers which use the transitions between subband states in or between quantum wells (QWs) to produce population inversion & lasing through band structure engineering. In FLASH, we will use state of the art deposition, characterization, and simulation tools to demonstrate, for the first time, that an industrial-viable technological platform is achievable exploiting electronic transitions in the conduction band of Ge quantum wells (QWs) produced with Ge-rich GeSi quantum structures. As a matter of fact, while interband recombination of electrons & holes in Si and Ge are inefficient due to their indirect bandgap, intersubband transitions provide an alternative path to a THz laser.

The innovative QCL will leverage on the non-polar nature of Si and Ge crystal lattices to potentially enable room-temperature operation and will emit > 1 mW power in the 1-10 THz range.

The proposed technology would be a game changer for many of the proposed and developed THz applications where the potential mass market requires sources at the €100-€1k price level rather than the typical €50k-100k now, having therefore a wide-ranging positive impact on the quality of life of European & international citizens.

 

Read More

  1.  Jones, Graham A.; Layer, David H.; Osenkowsky, Thomas G. (2007). National Association of Broadcasters Engineering Handbook. Taylor and Francis. ISBN 978-1136034107.
  2. Ahi, Kiarash (26 May 2016). "Advanced terahertz techniques for quality control and counterfeit detection". Proc. SPIE 9856, Terahertz Physics, Devices, and Systems X: Advanced Applications in Industry and Defense, 98560G. Terahertz Physics, Devices, and Systems X: Advanced Applications in Industry and Defense. 9856: 98560G. doi:10.1117/12.2228684. Retrieved 26 May 2016.
  3. Ahi, Kiarash (2018). "A Method and System for Enhancing the Resolution of Terahertz Imaging". Measurement. doi:10.1016/j.measurement.2018.06.044. ISSN 0263-2241.
  4.  JLab generates high-power terahertz light. CERN Courier. 1 January 2003.
  5.  Virginia Diodes Virginia Diodes Multipliers Archived 15 March 2014 at the Wayback Machine.
  6.  Köhler, Rüdeger; Alessandro Tredicucci; Fabio Beltram; Harvey E. Beere; Edmund H. Linfield; A. Giles Davies; David A. Ritchie; Rita C. Iotti; Fausto Rossi (2002). "Terahertz semiconductor-heterostructure laser". Nature. 417 (6885): 156–159. Bibcode:2002Natur.417..156K. doi:10.1038/417156a. PMID 12000955.
  7. Scalari, G.; C. Walther; M. Fischer; R. Terazzi; H. Beere; D. Ritchie; J. Faist (2009). "THz and sub-THz quantum cascade lasers". Laser & Photonics Review. 3 (1–2): 45–66. Bibcode:2009LPRv....3...45S. doi:10.1002/lpor.200810030.
  8. Science News: New T-ray Source Could Improve Airport Security, Cancer Detection, ScienceDaily (27 November 2007).
  9. Engineers demonstrate first room-temperature semiconductor source of coherent terahertz radiation Physorg.com. 19 May 2008. Retrieved May 2008
  10.  Peeling adhesive tape emits electromagnetic radiation at terahertz frequencies www.opticsinfobase.org 6 August 2009. Retrieved August 2009
  11.  Hewitt, John (25 February 2013). "Samsung funds graphene antenna project for wireless, ultra-fast intra-chip links". ExtremeTech. Retrieved 8 March 2013.