Light scattering properties of random media with a structure of laser speckle

Abstract

We study the light scattering properties of random media which have the refractive index distribution of threedimensional (3D) clipped laser speckle structures. To evaluate the performance of the speckle media as random laser cavities, we calculated the energy density and the local quality factor inside the media by means of the 3D finite difference time domain (FDTD) method. It is shown that the random media fabricated with the use of three speckle waves superposed without interference have the scattering strength as large as that of particulate media used conventionally for random laser media. To realize the speckle random media, we employed a technique of holographic lithography and fabricated polymer random media by illuminating photopolymer with one or two speckle waves. The far field scattering pattern of the sample media was measured to estimate the refractive index distribution of the samples. The experimental results suggest that a fibrous index structure, which is characteristic of 3D speckle patterns, is formed inside the sample media.