Cross-phase modulation of incoherent light in single-mode optical fibers

When two optical incoherent beams copropagate in an optical fiber, the intensity-dependent refractive index couples the two beams through a nonlinear process known as cross-phase modulation. We show, for the first time to our knowledge, experimental evidence on cross-phase-modulation-induced correlation time reduction and a concomitant growth of the frequency components of the two copropagating incoherent waves in a singlemode optical fiber. Theoretical analysis agrees well with experimental data.