Experimental demonstration of an ultracompact polarization beamsplitter based on a multimode interference coupler with internal photonic crystals

Abstract

The fabrication and characterization of a compact InP-based polarization beamsplitter (PBS) is presented. A multimode interference (MMI) coupler with an internal air hole photonic crystal (PhC) section is utilized to separate the two polarizations. The PhC structure in the middle of the MMI is polarization dependent, so that one polarization is reflected and the other one is transmitted; both are collected by the respective output ports of the MMI coupler. The obtained experimental results show that the PBS as short as ~400 µm has an extinction ratio as large as 15 dB.