  On-chip optical isolators, functioning as unidirectional gates for light,
play a crucial role in maintaining signal integrity, preventing laser
destabilization, and fortifying the overall performance of optical systems. In
this paper, we propose a five-layered heterostructure consisting of a
magneto-optic material sandwiched between parallel dielectric slab waveguides.
Under TMOKE configuration, the coupled optical modes undergo an electromagnetic
profile transformation that can be harnessed to confine the input mode in one
waveguide during forward propagation and in the other during backward
propagation. Together with radiative subwavelength gratings, such a system can
provide a 20dB isolation ratio with negligible insertion losses.
