Reduction of Ge-on-Si waveguide propagation loss by laser and hydrogen annealing

Leh Woon Lim; Andrew Whye Keong Fong; Rachel Chen Fang Ang; Roth Qin Gui Voo; Justin Nian Hong Teh; Md Hazwani Khairy Md Husni; Hong Cai; Landobasa Y. M. Tobing; Nanxi Li; Surasit Chung; Lennon Yao Ting Lee

doi:10.1117/12.2649846

17 March 2023 Reduction of Ge-on-Si waveguide propagation loss by laser and hydrogen annealing

Leh Woon Lim, Andrew Whye Keong Fong, Rachel Chen Fang Ang, Roth Qin Gui Voo, Justin Nian Hong Teh, Md Hazwani Khairy Md Husni, Hong Cai, Landobasa Y. M. Tobing, Nanxi Li, Surasit Chung, Lennon Yao Ting Lee

Author Affiliations +

Proceedings Volume 12424, Integrated Optics: Devices, Materials, and Technologies XXVII; 1242414 (2023) https://doi.org/10.1117/12.2649846
Event: SPIE OPTO, 2023, San Francisco, California, United States

Conference Poster

Abstract

Germanium-on-Silicon (Ge-on-Si) platform has been demonstrated as an excellent candidate for mid-infrared photonics applications, including on-chip mid-infrared spectroscopy and biochemical sensing. However, this platform is often saddled by high propagation loss due to a combination of threading dislocation defects at the Ge/Si interface, absorption in the silicon for λ < 8 μm, and surface scattering due to sidewall roughness. This work investigates the effects on loss reduction through different annealing techniques on Ge-on-Si waveguides fabricated using CMOS-compatible processes. We explore the use of local laser annealing at waveguide sidewalls, whereby the fluence was varied. A non-local annealing technique in hydrogen ambient was also employed as comparison. The propagation losses for wavelengths, ranging from λ = 5 μm to λ = 11 μm, were systematically characterized by fabricating waveguide and grating coupler structures on the same chip. Cutback measurements were performed by varying the waveguide length (of the same width) from L = 1 mm to L = 4 mm. Both hydrogen and laser annealing experiments show marked reduction in the propagation loss, by up to 27% and 46% respectively. This finding paves the way for post-processing techniques to reduce propagation loss in Ge-on-Si platform, which will enable various on-chip mid-IR applications in the future.

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Leh Woon Lim, Andrew Whye Keong Fong, Rachel Chen Fang Ang, Roth Qin Gui Voo, Justin Nian Hong Teh, Md Hazwani Khairy Md Husni, Hong Cai, Landobasa Y. M. Tobing, Nanxi Li, Surasit Chung, and Lennon Yao Ting Lee "Reduction of Ge-on-Si waveguide propagation loss by laser and hydrogen annealing", Proc. SPIE 12424, Integrated Optics: Devices, Materials, and Technologies XXVII, 1242414 (17 March 2023); https://doi.org/10.1117/12.2649846

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