I am an Iranian graduate student in the group of "Photon Scattering" at AMOLF, working under supervision of Ad Lagendijk.

My research topic is about observation of Anderson localization of light in strongly-scattering media. I am also interested in Anisotropic diffusion of light and optical non-linearity in scattering media.

2009-10-16: The multifractal structure of unltrasound waves close to the Anderson transition point
Waves usually diffuse through random materials. This fact allows light to travel through thick clouds and electrons to conduct through metals. But disorder can sometimes bring wave propagation to a complete halt. This remarkable phase transition from conductor to insulator, suggested by Philip Anderson in 1958, is known as Anderson localization. Ad and I, together with John Page and Anatoliy Strybulevych from Manitoba, Canada, and Bart van Tiggelen from Gronoble have uncovered the essential structure of waves close to the transition point.
We studied ultrasound propagation in a disordered network of aluminum beads. Just below the Anderson transition threshold wildly fluctuating forked wave-patterns, so-called multifractals, arise. The observation of multifractality in waves finally brings theories of the structure of the localization transition developed over the last 25 years, face to face with reality. The Anderson localization transition, once such an out-of-reach complex theory that Philip Anderson called his seminal paper "the unrecognizable monster" in his 1977 Nobel prize lecture, has evolved into a sub-branch of condensed matter theory with applications found in electronic conductivity of solids, transport of light and sound in multiple-scattering media, the quantum hall transition, high-T_c superconductivity, and the conductivity of Graphene. In fact, the concept of multifractality extends beyond localization. Multifractals are found in many complex systems such as turbulence, earthquakes, and patterns of rainfall.

2009-07-31: Light reveals its speed under pressure!
Measuring how fast light energy travels is not so easy, but inside opaque materials, like clouds, bone, skin, or paint the problem is particularly hairy. We have teased out this rate of transport using a simple, yet novel, trick: changing the ambient pressure. As the pressure is slowly tuned so is the so-called effective refractive index, which determines the speed of light. Even though the light is following an extremely complex path as it bounces through the material, its speed can be characterized by tracking the influence of pressure on the outgoing light intensity pattern. So simple and direct is the technique that it offers an entirely new way for probing inside important biological materials such as bone or wood as well as complex photonic materials such as photonic crystals or metamaterials.
Our recent letter on this subject is published in Physical Review Letters (Vol. 103, No. 053903). ScienceNews Magazine has also publicized this work here.