Mode-Selective Absorption and All-Optical Control Between Two Transverse Modes on Silicon-on-Insulator

Mode-selective absorption is realized by designing the ridge waveguide structure on silicon-on-insulator combined with two metal titanium (Ti) strips located on the two waveguide edges. The TE
₁
mode can be much easier to permeate the waveguide edges by designing the waveguide structure carefully. Therefore, the overlap between the TE
₀
and TE
₁
modes is reduced in the cross section and then the TE
₁
mode can be absorbed selectively by Ti strips. According to the opto-thermal effect, the refractive index of the waveguide will increase when the temperature rises. As a result, this waveguide structure can achieve all-optical control between two transverse modes with compact structure and low power consumption. As an example, a novel all-optical switch based on the proposed waveguide structure and Bragg grating was designed and numerically studied. We think the proposed structure may give a new way for all-optical control between two transverse modes, especially for the applications in the integrated mode division multiplexing systems.