Aluminum nitride waveguide beam splitters for integrated quantum photonic circuits

TL;DR

This paper presents the development and characterization of aluminum nitride waveguide beam splitters integrated into quantum photonic circuits, demonstrating high-quality polarization splitting and quantum interference.

Contribution

It introduces sputtered polycrystalline AlN waveguide beam splitters with tunable splitting ratios and high extinction ratios for integrated quantum photonics.

Findings

Achieved polarization beam splitters with >10 dB extinction ratio.

Demonstrated Hong-Ou-Mandel interference with 91.7% visibility.

Fabricated waveguide directional couplers with 50:50 to 99:1 splitting ratios.

Abstract

We demonstrate integrated photonic circuits for quantum devices using sputtered polycrystalline aluminum nitride (AlN) on insulator. The on-chip AlN waveguide directional couplers, which are one of the most important components in quantum photonics, are fabricated and show the output power splitting ratios from 50:50 to 99:1. The polarization beam splitters with an extinction ratio of more than 10 dB are also realized from the AlN directional couplers. Using the fabricated AlN waveguide beam splitters, we observe the Hong-Ou-Mandel interference with a visibility of 91.7 +(-) 5.66 %.