Superbunching effect of classical light with a digitally designed spatially phase-correlated wave front

Abstract

Superposition of multiple indistinguishable two-photon paths is introduced by means of a digital wave front encoding technique to design a spatially phase-correlated wave front of a light field, which could result in a superbunching effect with a bunching peak much larger than 2, the theoretical bunching peak of thermal light. Experimentally, we demonstrated a bunching peak of $11.72\ifmmode\pm\else\textpm\fi{}0.05$ with the digitally designed phase-correlated wave front of classical light, which can be improved further on. A significant improvement of the visibility of the second-order interference fringes and ghost imaging was also experimentally demonstrated. Our method provides a convenient digitally controllable way to implement superposition of multiple different but indistinguishable two-photon paths, and therefore to modify the optical coherence properties of photons. Such a superbunching effect may have potential applications in improving the visibility of correlation interference and imaging, and enhancing the efficiency of two-photon nonlinear effects such as two-photon absorption effect.