Ultracompact Low-Loss Grating Couplers

Fuente: arXiv
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Autores principales: Huang, Shiang-Yu, Zatsch, Jonas, Engling, Tim, Huster, Jeldrik, Barz, Stefanie
Formato: Preprint
Publicado: 2025
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author Huang, Shiang-Yu
Zatsch, Jonas
Engling, Tim
Huster, Jeldrik
Barz, Stefanie
author_facet Huang, Shiang-Yu
Zatsch, Jonas
Engling, Tim
Huster, Jeldrik
Barz, Stefanie
contents Fiber-to-chip couplers play a crucial role in interfacing on-chip photonic circuits with other optical systems or off-chip devices. Downsizing the couplers via topology optimization addresses the demand for high-density integration and improves the scalability of photonic integrated systems. However, these optimized couplers have yet to reach the performance level demonstrated by their conventional counterparts, leaving room for further improvement. In this work, we apply topology optimization to design single-polarization 1D and dual-polarization 2D grating couplers incorporating bottom reflectors and achieve sub-decibel coupling efficiency. Both types of couplers are fabricated on the silicon-on-insulator platform with dimensions of mere 14 $μ$m $\times$ 14 $μ$m and are compatible with standard single-mode fibers at normal incidence. From our experimental characterization, the measured peak coupling efficiency of the topology-optimized 1D and 2D couplers is -0.92(1) dB and -0.86(13) dB, respectively, within the telecom C-band. Our demonstration provides a coupling solution for photonic applications requiring high efficiency and high-density integration, such as spatial division multiplexing and photonic quantum technologies.
format Preprint
id arxiv_https___arxiv_org_abs_2510_15622
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Ultracompact Low-Loss Grating Couplers
Huang, Shiang-Yu
Zatsch, Jonas
Engling, Tim
Huster, Jeldrik
Barz, Stefanie
Optics
Quantum Physics
Fiber-to-chip couplers play a crucial role in interfacing on-chip photonic circuits with other optical systems or off-chip devices. Downsizing the couplers via topology optimization addresses the demand for high-density integration and improves the scalability of photonic integrated systems. However, these optimized couplers have yet to reach the performance level demonstrated by their conventional counterparts, leaving room for further improvement. In this work, we apply topology optimization to design single-polarization 1D and dual-polarization 2D grating couplers incorporating bottom reflectors and achieve sub-decibel coupling efficiency. Both types of couplers are fabricated on the silicon-on-insulator platform with dimensions of mere 14 $μ$m $\times$ 14 $μ$m and are compatible with standard single-mode fibers at normal incidence. From our experimental characterization, the measured peak coupling efficiency of the topology-optimized 1D and 2D couplers is -0.92(1) dB and -0.86(13) dB, respectively, within the telecom C-band. Our demonstration provides a coupling solution for photonic applications requiring high efficiency and high-density integration, such as spatial division multiplexing and photonic quantum technologies.
title Ultracompact Low-Loss Grating Couplers
topic Optics
Quantum Physics
url https://arxiv.org/abs/2510.15622