Integrated fiber optic probe for dynamic light scattering

An integrated fiber optic probe, comprising a monomode optical fiber fusion spliced to a short length of a graded-index multimode fiber, is fabricated for use as a coherent receiver in dynamic light scattering. The multimode fiber is cleaved to provide a gradient-index fiber lens with a focal length of 125 µm and an ƒ-number close to unity. An integrated fiber receiver is used to measure the intensity-intensity autocorrelation data from a 0.05% by weight concentration of an aqueous suspension of polystyrene latex spheres. Analysis of 100 independent data sets indicates that the particle size can be recovered with an accuracy of ±1%.