Multimode interference dynamic light scattering.

When dealing with dynamic scattering systems, being able to collect strong signals while maintaining a high signal-to-noise ratio (SNR) is critical. It is well known that a spatially coherent measurement provides the largest SNR, while a partially coherent one provides better means for proper spatial averaging. In this Letter, we present a robust implementation of a fiber-based, single-mode, common-path interferometer assisted by multimode interference. We show that light can be efficiently collected from larger coherent regions while keeping a high SNR that is comparable to that of a pure single-mode arrangement. Additionally, our implementation allows having both a stable local oscillator encoding information on the fiber-medium interface and a linear dependence on scattering density. These two attributes, in turn, permit accessing the effective optical properties of the dynamic complex system.