Optical switch based on multimode interference coupler

An optical switch based on the multimode interference (MMI) coupler is demonstrated in this letter. The device is designed and fabricated in polymeric materials and the thermooptic (TO) effect of polymers, which has a negative TO coefficient, is employed to change the self-imaging effect of a side-heated MMI coupler and realize optical switching. The switching power is only 22 mW. The experimental results show that the crosstalk of the switch is about -20 dB at both the cross and bar states.