By using the variational approach, we find that two mutually incoherent beams with different widths and wavelengths can form a Manakov vector soliton due to nonlocal nonlinearity. For such solitons to exist, the total incident power must be equal to a critical value and the ratio of the square of the beamwidths must be inversely proportional to the ratio of the wave numbers. The periodic oscillations of such vector solitons are also studied extensively when the incident power does not satisfy the necessary condition for stability.

• Received 7 November 2007

DOI:https://doi.org/10.1103/PhysRevA.77.015811