Abstract

Since the recent demonstration of self-trapping of a quasi-monochromatic partially spatially incoherent light beam¹ and of a white light beam that is both, spectrally and spatially incoherent,² there has been increased interest in so-called multimode solitons. These are self-trapped beams that constitute more than one transverse mode. More specifically, a soliton forms when the optical beam induces a waveguide via the nonlinearity and is guided in its own induced waveguide. Prior to the observations reported in Refs. 1 and 2, all observed solitons were such that only the lowest mode in the induced waveguide was populated. Therefore, all observed solitons were single mode and “single humped” (had a single intensity peak). However, in saturable nonlinear media, the induced waveguide can be multimode.³ When more than one mode of the induced waveguide is populated, the soliton is multimode and can have more than one intensity peak (multihump). For such a multimode soliton to exhibit a stationary nonevolving profile throughout propagation, the modes must not interfere with each other because this would cause a periodic oscillation in the optical intensity and thus give rise to a periodic induced waveguide. This can be achieved in two manners: (1) the modes are polarized orthogonal to each other,⁴ or (2) the modes are incoherent with respect to each other. Here we employ the latter option and believe we show the first experimental demonstration of a multihumped multimode soliton.

© 1998 Optical Society of America