Electrical signal-to-noise ratio improvement in indirect detection of mid-IR signals by wavelength conversion in silicon-on-sapphire waveguides

Planar waveguide devices based on silicon-on-sapphire are emerging as a bridge between mid-infrared (IR) and near-IR wavelength through frequency conversion process. We analyze the limits of indirect detection of mid-IR signals by wavelength conversion in such waveguides and investigate signal-to-noise ratio improvement that is attainable with respect to direct detection using state of the art commercial detectors. Our calculation shows that, in addition to room temperature and high speed operation, the proposed indirect detection can improve the electrical signal-to-noise ratio up to 40 dB compared to direct detection by PbSe, HgCdTe, and InSb detectors, especially in detection of weak mid-IR signals.