An accurate investigation of an integrated optical polariser has been presented. The transverse magnetic (TM)-passing property for an asymmetrical slab with anisotropic cladding that behaves as negative or positive uniaxial crystal has been evaluated. After a modal analysis, the polarisation of the electromagnetic (EM) field is evaluated by means of transmission line matrix-integral equation (TLMIE) method which performs a 3D full-wave modelling of the structure (i) including dielectric losses and (ii) for different slant angle of the laminated cladding. The TLMIE method permits to maximise the TM-passing property for a single-mode channel with anisotropic cladding.