Chip-scale Mid-infrared Sensing Systems Based on Integrated Silicon Photonics

Mid-infrared (MIR) has great potential for sensing applications. We are engaged in the research of MIR on-chip sensing systems based on integrated silicon photonics and are devoted to solving bottleneck problems including low photon energy in the MIR, low proportion of evanescent field in waveguides, large loss of substrate materials, etc., so as to improve device performance, working wavelength, and system integration level. We have obtained the following achievements: First, we developed waveguides with strong slow light effect by revealing the dispersion engineering mechanism, and realized compact and high-performance waveguide-integrated photodetectors through quantitatively verifying and utilizing the slow light effect to enhance the light-matter interaction; Second, we realized waveguide sensors with ppm level limits of detection (LoDs), through developing subwavelength grating metamaterial waveguides with low loss and high external optical field proportion; Third, we realized on-chip sensing quasi-system featuring the integration of photodetector and sensor at wavelengths beyond 6 μm and a sub-1% level on-chip LoD, by developing transfer printing technology to replace the substrate and designing hybrid plasmonic waveguides to enhance photodetection. Our results pave the way toward fully integrated on-chip MIR sensing systems for widespread sensing applications.