Design of an insensitive-polarization all-optical switch based on multimode interference structures

•This paper presents a new insensitive all-optical switch using 2 × 2 MMI couplers based on chalcogenide glass on silica material.•Nonlinear directional coupler is placed at an outermost arm to realize phase shifts for switching operation.•High intensity control optical beam is used in the phase shifter.•3D-BPM is used for designing and optimizing the switch.•Numerical simulation results have shown good performance, high bandwidth and large tolerance.

This paper presents a new design for an insensitive-polarization all-optical switch using 2 × 2 multimode interference (MMI) couplers. The switching structure can operate at central operating wavelength 1550 nm for both polarizations. A nonlinear directional coupler is used to realize the phase shifter and therefore switching mechanism is obtained. The transfer matrix method and beam propagation method are used to design and optimize the whole device structure.