Benchmarking Dual-Polarization Silicon Nitride Photonic Integrated Circuits for Trapped-Ion Quantum Technologies

TL;DR

This paper presents the design, fabrication, and characterization of silicon nitride photonic integrated circuits supporting dual polarization modes, enhancing optical control in trapped-ion quantum systems.

Contribution

It introduces dual-polarization silicon nitride PIC components with comparable losses, enabling more flexible optical addressing for trapped-ion quantum technologies.

Findings

Supports both TE and TM modes with low optical losses

Enables outcoupling of collimated beams for both polarizations

Provides distinct emission angles for polarization control

Abstract

Trapped ions are one of the most advanced platforms for quantum technologies, with applications ranging from quantum computing to precision timekeeping. A crucial step towards more compact and scalable systems involves integrating photonic integrated circuits (PICs) into surface ion traps to enable on-chip light delivery and optical addressing of individual ions. Currently, most implementations rely solely on transverse-electric (TE) mode grating couplers, where the emitted light is polarized in the plane of the chip. In this work, we design, fabricate and characterize silicon nitride (Si\(_3\)N\(_4\)) PIC components, including incoupling structures, splitters, and grating couplers that support both TE and transverse-magnetic (TM) modes with comparable optical losses. We benchmark the PIC at 760\,nm, which is a typical wavelength for Yb$^{+}$-applications. The fabricated grating couplers enable the outcoupling of collimated free-space beams for both polarizations, exhibiting distinct emission angles. This dual-polarization capability gives more flexibility in polarization control and expands the accessible optical design space for trapped-ion quantum technologies.