Ultra-Broadband and Low-Loss Silicon-Based Power Splitter Based on Subwavelength Grating-Assisted Multimode Interference Structure

Abstract

High-performance and compact power splitters are fundamental components in on-chip photonic integrated circuits (PICs). We propose a silicon-based power splitter based on a subwavelength grating (SWG)-assisted multimode interference (MMI) structure. To shorten the device size and enhance the device performance, an inverse-tapered SWG is embedded in the central region of the MMI and two rows of uniform SWG are embedded on both sides, together with two right-angled cutting structures on the input side. According to the results, the MMI length was obviously reduced to 3.2 μm (5.2 μm for conventional MMI structure under the same waveguide width), while the insertion loss (IL) and reflection loss were 0.08 dB and <−35 dB, respectively. Moreover, the allowable working bandwidth could be extended to 560 nm by keeping IL <0.6 dB, covering the whole optical communication band. On the basis of these features, we believe that such a power splitter is very promising for building on-chip large-scale PICs where power splitting is indispensable.