LAUSR

This theoretical modeling and simulation the design and projected performance of an on-chip detector of trace gases using photonic matched filters, with operation in the 3–5-μm mid-infrared range. The thermo-optically tuned multi-Sagnac loop Mach–Zehnder interferometer (MZI), based on the germanium-on-silicon nitride technological platform, has been adopted to detect the signature of gases with regularly spaced and narrow absorption lines. The MZI arms are comprised of an N-cascaded connection of Sagnac loop reflectors, each pair separated by a waveguide whose length is designed according to the line spacing of the gas under detection. Detection of one or two gas absorption bands using one filter band is achieved at the Drop port of an MZI filter having on each arm the apodized Hamming Bragg waveguide grating. We performed parametric analysis on the GON platform to find the design rules for the waveguide gas cell and the Hamming or multi-Sagnac filters targeted at CH4 or CO2 or N2O or SO2 or CO. The analysis predicted good sensor performance.