Terahertz spectroscopy and imaging

The THz band is located between the infrared and microwave domains and comprised typically between 100 GHz and 30 THz. This electromagnetic domain has been relatively less studied than others because of the lack of efficient generation sources and sensitive detection systems. The emergence of low cost and compact ultrashort lasers, that permits the generation of THz waves, is changing this situation.

Besides, the properties of THz waves like its non-ionizing behaviour, capacity to penetrate various materials, spectral signature of most molecules…, makes this technology particularly interesting for non-destructive testing applications.

Multitel proposes :

• Characterization (imagery and spectroscopy) of different samples in the  terahertz band.
• Development of femtoseconde laser sources pour THz generation.

Example of a 1.55 µm femtoseconde laser developed by Multitel

Spectroscopy

 

• Possibility to cover a spectrum from 0.1 to 6 THz.
• Materials characterization (absorption or refractive index in the THz band for instance)
• Thickness measurment

Imaging

• Intensity mapping
• Phase mapping
• Multi-spectral imaging

Example of characteristics of laser sources developed by Multitel for THz generation:

• 70 fs at 1550 nm
• 100 mW average power at 50 MHz repetition rate
• All-in-fibre configuration, compact, stable and reliable

 

 

Properties of THz radiations

• Non ionizing, non-invasive et non destructive
• Low absorption from many materials (paper, plastics, wood, textiles)
• High absorption from polar molecules (like water for instance)
• High reflexion onto metallic surfaces
• Different THz signatures exist for many materials (Pharmaceutical compound, chemical elements, pollutants, plastics…

Application fields

• Non destructive materials evaluation
• Thin films characterization
• Pharmaceutical components elaboration and control
• Recycling
• Control of manufacturing processes
• Security
• Food industry
• Biomedical,…