A highly sensitive voltage interrogation method using electro-optically tunable waveguide coupled surface plasmon resonance sensors

We present a highly sensitive detection method using electro-optically (EO) tunable waveguide coupled surface plasmon resonance (WCSPR) sensors by theoretical simulation. In this method, light is focused through a prism onto metal surface of the WCSPR sensor and the reflection is collected with a bicell photodetector. Time varied scanning DC electrical signal is applied on the waveguide layer of the WCSPR sensor and the ratio of the differential signal to the sum signal of the photodetector is calculated after each change. For each analyte, we get voltage-ratio curve after voltage scanning. Taking the ratio for a reference analyte calculated with null DC voltage applied as resonant ratio, different resonant voltages can be found in the voltage-ratio curves for different analytes. Theoretical simulation shows a high linearity between the resonant voltages and the refractive index (RI) of analytes. A sensitivity as high as 2.34×10⁵ V/RIU can be expected in this method.