[20a-P4-1~10] 3.15 Silicon photonics

▲ [20a-P4-3] Investigation of Low-loss Mid-infrared Waveguide Using n-type Ge

〇(M2)Ziqiang Zhao¹, Chongpei Ho¹, Shinichi Takagi¹, Mitsuru Takenaka¹ (1.Tokyo Univ.)

Keywords:Mid-Infrared, Waveguide, Germanium

For decades, germanium has been attracting tremendous attention from scientists and engineers for its superior properties in both electronic and photonic applications compared with silicon. As a platform of electronic-photonic integrated circuits operating at MIR wavelengths, we have proposed the Ge CMOS photonics platform which uses a Ge-on-Insulator wafer. We have demonstrated Ge passive and active waveguide devices operating at a 2-mm wavelength on a GeOI wafer, while the propagation loss is still high probably due to the hole-induced free-carrier absorption in Ge. In this we investigated the impact of n-type Ge on the propagation loss. When the waveguide width is less than 0.8 mm, the propagation loss of both Ge and Si waveguides increases rapidly due to the sidewall roughness. When the waveguide width is greater than 1 mm, the propagation loss of the n-type Ge waveguide is significantly smaller than that of the p-type Ge waveguide, and close to that of the Si waveguide.