Ultra-Compact and Ultra-Broadband Polarization-Insensitive Mach–Zehnder Interferometer in Silicon-on-Insulator Platform for Quantum Internet Application

Abstract

Polarization dependence in integrated silicon photonics has a detrimental effect on the manipulation of quantum state with different polarizations in the quantum technology. Those limits have profound implications for further technological developments, especially in quantum photonic internet. Here, we propose a polarization-independent Mach–Zehnder interferometer (MZI) structure based on a 340 nm-thick silicon-on-insulator (SOI) platform. The MZI facilitates low loss, broad operating bandwidth, and large tolerance of the fabrication imperfection. We achieve an excess loss of <10% and an extinction radio of >18 in the 100 nm bandwidth (1500∼1600 nm) for both transverse electric (TE) and transverse magnetic (TM) modes. We numerically demonstrate an interference visibility of 99% and a polarization-independent loss (PDL) of 0.03 for both polarizations at 1550 nm. Furthermore, by using the principle of phase compensation and self-image, we shorten the length of the waveguide taper by almost an order of magnitude with the transmission of >95% for both TE and TM polarizations. Up to now, the proposed structure could significantly improve the integration and promote the development of monolithic integrated quantum internet.

High-Performance Polarization-Independent Beam Splitters and MZI in Silicon Carbide Integrated Platforms for Single-Photon Manipulation

“…The visibility of the MZI for the TE and TM polarizations is calculated as high as 99.0 ± 0.4% and 98.7 ± 0.6%, respectively, confirming the high performance of the polarization-independent MZI at ultra-low power. The classical interference pattern of the MZI can reflect its quantum interference pattern [47], [48]. Thus, it is fair to infer that these devices can also perform well in the quantum regime.…”