The Terahertz Laboratories

Parameter Extraction Algorithm

Transfer Function based refractive index extraction algorithm for THz-TDS

To use the algorithm, follow the link at the bottom of the page.

This algorithm uses a transfer function to extract a refractive index from a slab material. It works for THz time domain spectroscopy measurements that have been taken in a transmission geometry. For inputs the algorithm requires; a time domain scan of a sample, a time domain reference scan, and the thickness of the sample. The algorithm will output the complex refractive index of the sample.

  • The complex refractive index of a material is determined by fitting a theoretically calculated transfer function to the experimental data.
  • The calculation of the theoretical transfer function is done using Fresnel coefficients
  • The calculation of the experimental transfer function is the division in frequency of the signal obtained with the same and a reference scan without the sample
  • Complex refractive index can be used to determine material properties such as relative permittivity, conductivity


Algorithm schematic


We cannot guarantee the accuracy of the results of the algorithm. If you need help email:

This algorithm is free. However, if you need results for publications we do require that you contact us first as we may be able to develop an algorithm that works better for your application



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