Biomedical subjects
Publications and source records attributed to J J Greffet.
We report the design of a tungsten thermal source with extraordinarily high directivity in the near infrared, comparable to the directivity of a CO2 laser. This high directivity is the signature of the long-range correlation of the electromagnetic field in the source plane. This phenomenon is due to the resonant thermal excitation of surface-plasmon polaritons.
Resonant transmission through metallic films is observed when a periodic array of holes is drilled. This phenomenon has been attributed to surface plasmon polaritons. We study a similar system made of an array of slits in a SiC film supporting surface phonon polaritons. We find a resonant transmission in the infrared. The role of surface waves is analyzed. We find that surface waves are excited at resonance but are not a necessary condition to obtain a resonant transmission.
This study is devoted to the examination of scattering of waves by a slab containing randomly located cylinders. For the first time to our knowledge, the complete transmission problem has been solved numerically. We have compared the radiative transfer theory with a numerical solution of the wave equation. We discuss the coherent effects, such as forward-scattering dip and backscattering enhancement. It is seen that the radiative transfer equation can be used with great accuracy even for optically thin systems whose geometric thickness is comparable with the wavelength. We have also shown the presence of dependent scattering.
We report experimental measurements of the extinction in a suspension of dielectric spheres. We find that the model originally introduced by Keller is in good agreement with the data provided that nonlocal effects are properly taken into account. We also find that the simple criterion establishing the regime of independent scattering previously introduced is not consistent with our data.