Multiple scattering of electromagnetic (EM) waves arises in disordered media with a refractive index varying on the scale of the wavelength. The diffusion approximation is a powerful tool to treat multiple scattering as a photon random walk, neglecting resonant phenomena. However, as the light intensity varies on a scale much smaller than the transport mean free path, resonances may occur in media formed by finite-size scatterers and break the diffusion approximation. The energy and phase velocity are very useful tools to reveal the onset of the resonant transport regime. In this paper the study of the propagation of terahertz (THz) waves through 3D random media by employing terahertz time-domain spectroscopy (THz-TDS) is addressed. Specifically, measurements of the electric field transmitted by samples of different thicknesses made of 1 mm diameter silica spheres dispersed in a paraffin matrix at different filling fractions are reported. This investigation has provided an accurate measurement of the EM field phase and, hence, information on the radiation propagation velocity that has enabled the first observation of a photonic glass at the THz range.

Terahertz Radiation Transport in Photonic Glasses / Gentilini, S.; Missori, M.; Ghofraniha, N.; Conti, C.. - In: ANNALEN DER PHYSIK. - ISSN 0003-3804. - 532:8(2020), p. 2000005. [10.1002/andp.202000005]

Terahertz Radiation Transport in Photonic Glasses

Gentilini S.;Ghofraniha N.;Conti C.
Ultimo
Supervision
2020

Abstract

Multiple scattering of electromagnetic (EM) waves arises in disordered media with a refractive index varying on the scale of the wavelength. The diffusion approximation is a powerful tool to treat multiple scattering as a photon random walk, neglecting resonant phenomena. However, as the light intensity varies on a scale much smaller than the transport mean free path, resonances may occur in media formed by finite-size scatterers and break the diffusion approximation. The energy and phase velocity are very useful tools to reveal the onset of the resonant transport regime. In this paper the study of the propagation of terahertz (THz) waves through 3D random media by employing terahertz time-domain spectroscopy (THz-TDS) is addressed. Specifically, measurements of the electric field transmitted by samples of different thicknesses made of 1 mm diameter silica spheres dispersed in a paraffin matrix at different filling fractions are reported. This investigation has provided an accurate measurement of the EM field phase and, hence, information on the radiation propagation velocity that has enabled the first observation of a photonic glass at the THz range.
2020
disordered photonics; multiple scattering; random media; terahertz time-domain spectroscopy
01 Pubblicazione su rivista::01a Articolo in rivista
Terahertz Radiation Transport in Photonic Glasses / Gentilini, S.; Missori, M.; Ghofraniha, N.; Conti, C.. - In: ANNALEN DER PHYSIK. - ISSN 0003-3804. - 532:8(2020), p. 2000005. [10.1002/andp.202000005]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1443451
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