Mid-infrared Photonic Chips for Real-time Gas Mixture Analysis

Real-time gas analysis on-a-chip was demonstrated using a mid-infrared (mid-IR) microcavity. Optical apertures for the microcavity were made of ultrathin silicate membranes embedded in a silicon chip using the complementary metal-oxide-semiconductor (CMOS) process. CH
4
, CO
2
, and N
2
O were selected as analytes due to their strong absorption bands at λ = 3.25–3.50 μm, 4.20–4.35 μm.