High-sensitivity polymer-based bimodal plasmonic refractive index sensors with polymer cladding.

Plasmonic refractive index sensors are essential for detecting subtle variations in the ambient environment through surface plasmon interactions. Current efforts utilizing CMOS-compatible, plasmo-photonic Mach-Zehnder interferometers with active power balancing exhibit high sensitivities at the cost of fabrication and measurement complexity. Alternatively, passive bimodal plasmonic interferometers based on SU-8 waveguides offer cost-effectiveness and a smaller device footprint.

Theoretical and Experimental Analysis of Single-Arm Bimodal Plasmo-Photonic Refractive Index Sensors.

In this paper, we study both theoretically and experimentally the sensitivity of bimodal interferometric sensors where interference occurs between two plasmonic modes with different properties propagating in the same physical waveguide. In contrast to the well-known Mach-Zehnder interferometric (MZI) sensor, we show for the first time that the sensitivity of the bimodal sensor is independent of the sensing area length. This is validated by applying the theory to an integrated plasmo-photonic bimodal sensor that comprises an aluminum (Al) plasmonic stripe waveguide co-integrated between two accessible SU-8 photonic waveguides.