Operation Principles for Optical Switches Based on Two Multimode Interference Couplers

In this paper, the operation principles for optical switches based on two multimode interference (MMI) couplers are discussed in detail. Based on the analytical expressions of transfer matrix of the MMI couplers, the control mechanism and principles of the two-stage MMI coupler based switch are derived. The device can be controlled by proportionally adjusting the interstage variable phase shifter array. N different switching states can be realized on this device.