Multiplexed Mach-Zehnder interferometer assisted ring resonator sensor.

A Mach-Zehnder interferometer assisted ring resonator configuration (MARC)-based multiplexed photonic sensor with a large measurement range is experimentally demonstrated. The presented MARC sensor consists of a balanced Mach-Zehnder interferometer and a ring resonator acting as a sensing component. It produces transmission responses with unique spectral signatures, which depend on the physical angular separation between the through port and the drop port waveguides. These unique spectral signatures enhance the effective free spectral range of ring resonators. Hence MARC sensors with a large measurement range are realized. We experimentally demonstrated that the measurement range from the MARC with 135° angular separation is 8x larger than a standard ring resonator. Moreover, by utilizing the MARC, we distinguished the responses from two and three ring resonators multiplexed together. These results verify proof-of-principle for the MARC-based sensors. This inexpensive compact multipurpose device holds promise for numerous applications.