Attenuated Total Reflection at THz Wavelengths: Prospective Use of Total Internal Reflection and Polariscopy

Capabilities of the attenuated total reflection (ATR) at THz wavelengths for increased sub-surface depth characterisation (bio-)materials are presented. The penetration a evanescent wave in biological samples is dependent on wavelength and temperature can reach 0.1–0.5 mm depth, due to strong refractive index change ∼0.4 ice-water transition; this quite significant important when studying samples. Technical challenges discussed using ATR uneven, heterogeneous, high with possibility frustrated internal (a breakdown mode into transmission mode). Local field enhancements interface numerical/analytical examples. Maxwell’s scaling used model behaviour absorber–scatterer inside materials prism realistic complex indices bio-materials. modality polarisation analysis proposed, its principle illustrated, opening an invitation experimental validation. sensitivity polarised between sample numerically modelled experimentally verified background (air) spectra. design principles active optical elements spectral filters outlined. results proposed concepts based conditions beamline Australian Synchrotron.