Observation of Anomalous Transport of Strongly Multiple Scattered Light in Thin Disordered Slabs

Abstract

Observation of anomolous transport of strongly multiple scattered light in thin disordered samples Kop, H.J.; de Vries, P.; Sprik, R.; Lagendijk, A.

Controlling waves in space and time for imaging and focusing in complex media

“…Although the particle-diffusion approach and radiative transfer theory 21 neglect the interference terms responsible for enhanced backscattering 22,23 and strong localization [24][25][26][27] , they are both remarkably effective at predicting the average intensity distribution 28 . The diffusion approach is concerned with the ensemble-averaged intensity, which is always smooth.…”

Propagation of Light in Disordered Semiconductor Materials

“…Much experimental work has been done on powders of TiO 2 [14,15,16]. TiO 2 is the dielectric with the highest refractive index in the visible, n = 2.7, and, although the TiO 2 samples were strongly scattering, the lowest value of the localization parameter was still far from the transition (kl s ≈ 6).…”

Diffusion in Translucent Media

“…Since waves are largely coherent in translucent samples and randomized in diffusive media, one might expect the total transmission to scale differently in these regimes. Surprisingly, however, measurements of total optical transmission, which includes both the scattered and unscattered waves, were found to be in accord with diffusion theory down to sample lengths of L~2ℓ 8,13,15 . We explore wave propagation on still shorter length scales with L ≪ ℓ to discover whether there is a lower limit in thickness below which the diffusion model fails.…”

“…Measurements of optical 11,15,18,19,42 and ultrasound 16 pulsed transmission through random slabs show that on average photons arrive earlier than predicted by diffusion theory even in samples with L > 5ℓ. The average delay time t D can also be determined from the transmission eigenvalues and energy density profiles of the transmission eigenchannels 37 (Supplementary Note 4).…”

“…The diffusion approach also describes the transport of classical and quantum waves in multiply scattering media [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] . Waves entering a static disordered sample interfere to produce a wavelength-scale speckled pattern of energy or particle density that is a unique fingerprint of the wave interaction with the disordered sample.…”