InGaAsP/InP multi-mode interference photonic switches for monolithic photonic integrated circuits

InGaAsP/InP semiconductor photonic switches using multi-mode interference (MIPS) are proposed for monolithic photonic integrated circuits. Changing the refractive indices of index-modulated regions located in the center of a multi-mode waveguide, controls its switching functions. It is predicted from calculations by an FD-TD (finite difference time domain) method that these devices can operate in various kinds of output schemes with typical device dimensions of about 8 μm width and 540 μm length. 1 × 2 InGaAsP/InP MIPS's with a high-mesa structure have been fabricated, and fundamental switching characteristics were measured. At the preliminary stage, switching was observed at 20mA current injection with about 37% extinction ratio. Switching efficiency and cross talk of the MIPS can be improved by optimizing the device dimensions and structure. The flexibility of setting the index-modulated regions suggests versatile operation of the MIPS, such as a photonic space division switch, a variable power splitter, or as an optical modulator.