Theoretical researchers who have worked on nonlinear beam propagation inside nonlinear medium can model spatial soliton stripes inside the medium. If one tries to observe experimental evidence, which instrument is suitable to utilize?
Probably addition of small doze of a luminescent dye may help. Dye must absorb radiation of interest; if it is ir radiation, multiphoton absorption can be employed, contrast being enhanced in this case
If we just want to observe the propagation behavior of an optical beam, we can use a CCD camera setting on the top of nonlinear medium. From the CCD, we can obtain the profiles of the solitons at different propagation position. The experimental setup described in Acta Physica Sinica, 56 258(2007) perhaps can be used. This paper is written in Chinese.
Of course if the medium is inhomogeneous at the wavelength or subwavelength scale, some scattered light can be observed at the right angle to the soliton propagation direction
Many different techniques can be indeed useful for such purposes....... it depends on the guest medium. The easiest if to use the soliton stripe as a cylindrical lens for othogonal light