Work

Suspended Germanium-on-Silicon Photonic Integrated Circuits Operating in the Long-Wave Infrared and Their Use for Ethanol Sensing

Year: 2026

Type: article

Abstract: Germanium-based integrated photonics is gaining attention due to its potential for mid-infrared wavelength applications, including environmental sensing, industrial gas monitoring, defense, and security. However, current germanium-on-silicon platforms face significant propagation losses at wavelengths above 8 μm, and gas sensing in this regime using a germanium waveguide has not been demonstrated to date. To address this challenge, we introduce a suspended germanium-on-silicon platform, where an 11 μm deep suspension gap ensures optical mode isolation from the lossy silicon substrate. The waveguide has a low propagation loss of 3.5 dB/cm at a wavelength of 9.2 μm. Furthermore, we demonstrate on-chip ethanol gas sensing in the long-wave infrared range with a detection limit of 925 ppm using this platform. Our method paves the way for extending the operating wavelength range of germanium-on-silicon integrated photonics into the long-wave infrared.

Source: ACS Photonics

DOI: 10.1021/acsphotonics.6c00154

Authors: Pen-Sheng Lin, Per-Erik Hellström, Charalampos Zervos, Frank Niklaus, Kristinn B. Gylfason

Institutions: KTH Royal Institute of Technology, National Technical University of Athens

Language: English

Topic: Photonic and Optical Devices

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,500

Funders: European Commission, HORIZON EUROPE Framework Programme, HORIZON EUROPE Digital, Industry and Space, H2020 LEIT Information and Communication Technologies