Silicon Plasmonics On-Chip Mid-IR Gas Sensor

A novel all silicon plasmonic structure is proposed with silicon access waveguides. In principle, a highly doped silicon acts as a plasmonic like media that carries two surface waves on each surface that interfere at the output waveguide. The top surface is considered as the sensing arm of this plasmonic Mach-Zehnder interferometer. The bottom surface is considered as the reference arm of the sensor. High sensitivity and small foot print are achieved using this integrated simple-all-silicon-based plasmonic design. The optimization process of the design and material properties yields enhanced sensitivity up to 16 000 nm/RIU at operating wavelength around 5100 nm. The proposed on-chip sensor has been utilized for different carbon gas. This study shows the capability of the proposed sensor to characterize different gases. Being built of CMOS compatible materials, this proposed design could be fabricated without altering the conventional fabrication steps in the CMOS foundry.