Development of Ge-based mid-infrared waveguide platform with strong optical confinement for on-chip gas sensing

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K14670
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Electron device/Electronic equipment
• Research Institution: NTT Basic Research Laboratories (2018); Tokyo City University (2017)
• Principal Investigator: Xu Xuejun 日本電信電話株式会社NTT物性科学基礎研究所, 量子光物性研究部, 主任研究員 (80593334)
• Research Collaborator: Osako Rikito
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: Mid-infrared photonics / Silicon photonics / Gas sensing / Germanium / Microresonator

Outline of Final Research Achievements

In this research, silicon-based mid-infrared (MIR) photonic platform has been developed for ultra-sensitive on-chip gas sensing. Ge-on-Si films with ultralow MIR absorption of less than 10 cm-1 have been grown by molecular beam epitaxy and post annealing. Fundamental building blocks, including optical waveguides, fiber-to-waveguide grating couplers, and microdisk resonators, have been realized on Ge-on-Si and silicon-on-insulator substrates. A MIR waveguide transmission measurement system has been established and high coupling efficiency over 10% between fiber and waveguide has been realized. Based on these device components, sensitivity analysis indicates that ultra-long effective optical absorption length on the order of meter can be readily achieved on-chip within device footprint of less than 0.04 mm2.

Free Research Field

半導体工学

Academic Significance and Societal Importance of the Research Achievements

The research indicates that the proposed MIR photonic platform is very promising for high sensitivity on-chip trace gas sensing, and represents a new direction for group-IV photonics. It thus pave the way to low-cost, practical, portable, and smart gas monitoring tools in industry and daily life.