THz materials : a complete guide

THz wavelengths are particularly interesting for various scientific, medical, and industrial applications due to their non-ionizing nature (safer than X-rays which are ionizing radiations) and ability to penetrate various materials.

Thz materials

What is THZ ?

Terahertz (THz) radiation refers to electromagnetic waves with frequencies ranging from 0.1 to 10 Thz (10^12 hertz). This spectral range lies between the microwave and infrared areas of the electromagnetic spectrum, corresponding to wavelengths from 3mm to 30µm.

Materials transparent to THz radiation

Different materials exhibit varying degrees of transparency to THz radiation. Below is a table listing some of the common materials that are transparent to THz waves, along with relevant technical information such as refractive index, absorption coefficient, bandgap, visible transparency, and relative pricing.

Thz materials comparison table
MaterialTransparent in the visibleRefractive index (@ 1 Thz)Absorption Coefficient (cm-1)Bandgap (eV)Pricing (relative)Remarks
TPX (polymethyl-pentene)yes1.46less than 0.05LowHighly transparent in the THz region, very good low temperature performances both optically and mecanicaly
Teflon (PTFE)no1.43less than 0.05LowExcellent THz transparency and low absorption
PE (polyethylene)no1.52less than 0.1very lowcommon low cost window for THz systems
COP (Cyclo-olefin polymer)no1.53less than 0.1lowGood optical properties
Diamondyes2.38less than 0.15.5very highExceptional thermal properties and mechanical resistance
HR-Si (High resistivity Silicon)no3.420.1-101.1Moderateeasy to work resistant material
Sapphire yes3.1-3.2less than 0.29.9HighExcellent thermal and chemical stability
ZnSe (Zinc Selenide)partial2.4less than 0.22.7ModerateAn alternative to HR-SI for THz lenses and windows
GaP (Gallium Phosphide)Yes3.2less than 0.52.26HighHigh refractive index and low absorption.
Fused silicayes2.1-2.40.1-0.58.9LowCheap inert material

To go further on these materials

Below some links introducing more into details the above mentioned materials, please follow them to get more insight.

Applications of THz optics

Thz optics are used in a wide range of applications :

  • Imaging systems: medical imaging, security scanning, and non destructive testing (food, medicine etc.)
  • Spectroscopy: identification of chemicals
  • Communications: high speed free space systems

As natural THz radiations are rather small, THz systems usually include a source, emitting THz radiations and a camera or sensor that will be used to receive the signal.

Looking for THz windows or THz lenses ?

SINOPTIX provides optical components, namely windows, spherical lenses, cylindrical lenses and hemispherical lenses in all of the above chart materials, don’t hesitate to contact us for a quote or technical information.

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