Integrated electro-optic tunable power splitter based on microring resonators having interleaved PN junctions

Abstract

An integrated high-speed novel electro-optic power splitter based on interleaved PN junction in a silicon microring resonator has been proposed, which can be used as an ultra-fast, dynamically tunable optical power splitter to efficiently distribute power between various optical stations in Network-on-chip (NoC). The main working principle behind such a device is that we can change the refractive index of the PN junction waveguide under an application of an external reverse bias voltage, enabling the resonator to work as a power splitter. The interleaved PN junction waveguides utilizing the features of greater overlap of the optical waveguide mode with the depletion layer compared to normal PN junction, provide the opportunity to maximize the change in refractive index with minimum applied reverse bias voltage. The carriers (electrons and holes) are depleted near to the p region and n region interface on applying a reverse bias voltage. The depletion region increases with the applied reverse bias voltage, which enhances more interaction with the propagating light. To evaluate the performance of the splitter, we have calculated the change in the effective refractive index and the optical loss due to the free carrier concentrations. The proposed optical power splitter is capable of tuning the power splitting ratio from 0.15 to 7.82, which is a very wide range of tunability with low power consumption (35 mW) and low external voltage (0-3.5 V). We have proposed the use of a high-speed Digital to Analog converter (DAC) to apply an external reverse bias voltage to the interleaved PN junction waveguide.