Foundry-Processed Mid-Infrared Thermo-Optic Phase Shifters

Mid-infrared (Mid-IR) thermo-optic phase shifters are key components in tremendous optoelectronic applications ranging from free-space communications to optical ranging. However, few studies reported the feasibility of developing mid-IR thermo-optic phase shifters based on silicon photonics foundries, which have been widely exploited in the telecommunication band. In this paper, we demonstrated thermo-optic phase shifters based on a multi-project wafer (MPW) service in two transparency windows of silica and atmosphere, namely, 2.35 μm and 3.27 μm wavelengths. Our results show that the developed phase shifters have a power consumption of 29 mW/π with an extinction ratio (ER) of 30.7 dB at 2.35 μm wavelengths, as well as a power consumption of 70 mW/π with an ER of 12.0 dB at 3.27 μm wavelengths. Moreover, we demonstrated modulated mid-IR light transmission in free space based on the developed devices. Our study is expected to open an avenue for developing mid-IR silicon photonic optoelectronic integrated circuits with standard silicon photonics foundries.