Generation of stochastic electromagnetic beams with controllable coherence

We experimentally generate a stochastic electromagnetic beam with controllable coherence, employing two crossed zero-twisted nematic liquid crystal spatial light modulators. The coherence of the stochastic electromagnetic beam can be controlled by the variation magnitude of phase modulation of the spatial light modulators. We measure the coherence properties of the beam using Young's interference experiment. The results showed that the coherence degree along two mutually perpendicular directions can be different and controlled by introducing two kinds of different phase modulation on the two spatial light modulators.