Ultra high sensitivity chemical photonic sensing by Mach–Zehnder interferometer enhanced Vernier-effect

In this paper an ultra high sensitivity chemical photonic sensor is proposed, employing a Mach–Zehnder interferometer (MZI)-enhanced Vernier effect. The proposed sensor is demonstrated to reach ultra high overall sensitivity (>1000 μm/RIU) and very low limit of detection (LOD < 10−6 RIU), with a compact, standard SOI chip. Furthermore, two very efficient sensors are designed. The first one is a CO2 sensor for health safety purpose, able to detect gas concentration as low as 5000 ppm. The second one is an ammonia sensor in aqueous solution, able to detect ammonia concentrations down to 2 ppm. The designed sensors are proposed in silicon on insulator (SOI) technology due to its compatibility with standard CMOS technology, but the enhanced Vernier effect could be applied to each technology allowing to simultaneously fabricate ring resonators and MZIs.