Scattering delay time of Mie scatterers determined from steady-state and time-resolved optical spectroscopy.
We have determined the scattering delay time of Mie scatterers (r = 255 nm quartz spheres in polyester resin) from a combination of steady-state (integrating-sphere) and time-resolved (frequency-domain) measurements performed in the multiple-scattering regime. The effective transport velocity of light was derived from intensity and phase measurements at four different wavelengths by using the time-integrated microscopic Beer-Lambert law. We could demonstrate a systematic underestimation of the effective transport velocity compared with the phase velocity in the medium. Assuming that this discrepancy was caused entirely by the transient nature of a single-scattering process, the data presented resulted in time delays of between 18 fs (lambda = 678 nm) and 177 fs (lambda = 1,064 nm) per scattering event. For three out of four wavelengths investigated, the measured values are in excellent agreement with values predicted by a theoretical model for the scattering delay time based on Mie theory.
Willmann
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S
Institute of Laser Medicine, Heinrich-Heine-University, Düsseldorf, Germany. willmann@uni-duesseldorf.de
Terenji
A
A
Busse
H
H
Yaroslavsky
I V
IV
Yaroslavsky
A N
AN
Schwarzmaier
H J
HJ
Hering
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P
D008027:Light; D008962:Models, Theoretical; D055095:Optics and Photonics; D017785:Photons; D012542:Scattering, Radiation; D013997:Time Factors