Terahertz radiation

Terahertz radiation is loosely defined as electromagnetic waves with frequency in the range 0.1-10 THz, corresponding to wavelengths of 3000-30 um, wavenumbers of 3-330 cm-1 and energy of 0.4-40 meV.

Terahertz radiation is safe and non-ionising. It bridges 
the gap between the mid-infrared and microwaves.

It can penetrate most non-conductive materials and has interesting spectroscopic and imaging capabilities:

  • Water content mapping
  • Tissue density mapping
  • Metals detection
  • Spectral identification

Several specific spectral lines of atoms, molecules and ions (rotational lines of light atoms and molecules, vibrational lines of very large molecules, fine-structure lines and inter-molecular interactions) and many characteristics energies of physical and biological systems (phonons, excitons, cyclotron resonance, hybridisation gap, collective excitations in spin materials, free carriers in semiconductors, hydrogen bond stretching, peptide backbone bending and torsion etc.) are located in the terahertz range. Furthermore, terahertz radiation is strongly absorbed by many polar liquids like water and alcohol, it is almost perfectly reflected by metals, it penetrates deeply into many materials such as ceramics or polymers, and unlike the X-ray it is non-ionising. The advantage over the microwave radiation is the higher resolution.

Applications are found in fields of security (detection of drugs, noxious gases, explosives, knives, guns), industry (quality control, thickness measurements, defects detection), biomedicine and pharmacy (in-vivo check up of carcinogenic tissues during a surgical intervention, blood and skin analysis, disease diagnostics, protein analysis, label-free DNA sensing), chemistry, atmosphere science (pollution monitoring, ozone-depletion monitoring), astrophysics (star formation) and fundamental research (exploitation of novel electronic and magnetic materials, characterisation of superconductors) etc.

Terahertz Quantum Cascade Lasers

Quantum cascade lasers (QCL) are electrically-pumped semiconductor lasers based on intersubband transition in the conduction band of the heterostructure. Population inversion and laser emission can be freely engineered. The QCL is the most mature source of coherent far-infrared emission from 60 to 250 um, i.e. 1.2 to 5 THz. These lasers work under cryogenic temperatures.

Alpes Lasers offers THz QCLs with center emission located in the range from 1.3 to 4.7 THz. Depending on their specifications and the requirements, the devices can be mounted in a small liquid-nitrogen dewar, in a flow-cryostat or in a cryogenic liquid-free mechanical cryocooler.  On demand, we are able to realise a customised solution. Please do not hesitate to contact us further for any questions. We are looking forward to discuss your project.