A light source assembly having N outputs, the assembly including: a light source arrangement arranged for supplying light to M inputs, where M an N independently of each other are integers and where M≥2 and M≥N; at least one optical couplers, each having at least one input arm and a plurality of output arms; and an integer number, P, of mode scramblers. The light source arrangement may include a broadband light source and a multimode coupler configured for receiving one or more light beams from the light source arrangement, wherein the one or more light beams being derived from the broadband light source and wherein a mode scrambler is arranged for mode scrambling one of said light beams before it enters the multimode coupler.