J. Eur. Opt. Society-Rapid Publ. 2026, 22, 56 Ó The Author( s), published by EDP Sciences, 2026 https:// doi. org / 10.1051 / jeos / 2026049 Available online at: https:// jeos. edpsciences. org
EOSAM 2025 Guest editors: Omar El Gawhary, Stefan Witte, Ignacio Moreno
Journal of the European Optical Society-Rapid Publications
RESEARCH ARTICLE
Benchmarking dual-polarization silicon nitride photonic integrated circuits for trapped-ion quantum technologies
Carl-Frederik Grimpe 1, Anastasiia Lüßmann-Sorokina 1, 2, 3, Guochun Du 1, *
, Pragya Sah 4, 5, Steffen Sauer 1, 2, 3, Elena Jordan 1, Rijil Thomas 4, Pascal Gehrmann 2, 3, Maksim Lipkin 4, 5, Stephan Suckow 4, Max C. Lemme 4, 5, Stefanie Kroker 1, 2, 3, and Tanja E. Mehlstäubler 1, 6, 7 1 Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig, 38116, Germany 2 Technische Universität Braunschweig, Institute of Semiconductor Technology, Hans-Sommer-Str. 66, Braunschweig, 38106,
Germany 3 Laboratory for Emerging Nanometrology( LENA), Langer Kamp 6a / b, Braunschweig, 38106, Germany 4 AMO GmbH, Otto-Blumenthal-Straße 25, 52074 Aachen, Germany 5 Chair of Electronic Devices, RWTH Aachen University, Otto-Blumenthal Str. 25, Aachen 52074, Germany 6 Leibniz Universität Hannover, Institut für Quantenoptik, Welfengarten 1, Hannover, 30167, Germany 7 Leibniz Universität Hannover, Laboratorium für Nano- und Quantenengineering, Welfengarten 1, Hannover, 30167, Germany
Received 29 January 2026 / Accepted 26 May 2026
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 transverseelectric( TE) mode grating couplers, where the emitted light is polarized in the plane of the chip. In this work, we design, fabricate and characterize key silicon nitride( Si 3 N 4) PIC components required for scaling trappedion based quantum systems to multiple operating zones, 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.
Keywords: Grating coupler, Silicon nitride, Ion traps, Dual-polarization.
1 Introduction
Trapped ions are a leading platform for numerous quantum applications, including sensing [ 1, 2 ], communications [ 3, 4 ], timekeeping [ 5, 6 ], and computing [ 7, 8 ].
The integration of nanophotonics into surface ion trap platforms has emerged as a promising route toward scalable quantum computing architectures and quantum sensors [ 9 – 16 ]. Monolithically integrated waveguides( WGs) and grating couplers( GCs) enable stable, well-defined optical beam delivery with a small footprint, mitigating the alignment sensitivity of free-space optical systems. Importantly, these photonic components are compatible with CMOS processes, enabling wafer-scale fabrication [ 17 ].
* Corresponding author: guochun. du @ ptb. de
Among available material platforms, silicon nitride( Si 3 N 4) has been developed as a mature and versatile option for visible and near-infrared operation [ 18 – 24 ]. Si 3 N 4 offers low propagation loss and high optical-power handling [ 18 ], together with CMOS-compatible fabrication suitable for both passive and nonlinear photonic devices. Advances in film-stress control, etch uniformity, and wafer-scale processing have improved reproducibility and yield [ 19, 21, 25 ], reinforcing Si 3 N 4 as a leading dielectric platform for visible integrated quantum technologies.
To date, most Si 3 N 4 photonic implementations in ion traps are optimized for transverse-electric( TE) polarization [ 9 – 11, 14, 16 ], where the electric field points parallel to the chip surface. The polarization of light determines the coupling to atomic transitions. Therefore, TE-optimized operation provides limited coupling directions, and placement options of the GC to deliver the correct polarization with
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