Computational investigation of nanohole array based SPR sensing using phase shift.

We present a new high spatial resolution sensor for monitoring refractive index variations caused by binding of organic and biological molecules to the metallic surface containing arrays of nanoholes. Signal transduction is provided through detecting the optical phase change in the extraordinary optical transmission (EOT) effected by surface plasmon resonance (SPR). These 2D nanoholes are well suited for the sensor chip format in which high dense integration is readily achievable. While the sensor operates at normal illumination, practical implementation of the sensor is much easier in comparison to the traditional Kretschmann arrangement for SPR sensing. Various design parameters of the device have been studied by simulation. Our results indicate that the scheme has a shot-noise limited sensitivity threshold of 4.37 x 10(-9) refractive index units (RIU) and a dynamic range of 0.17 RIU, which compare favorably with typical SPR sensors, particularly in terms of achieving high resolution and wide dynamic range sensor attributes. The phase change is also quite linear over the entire refractive index detection range.