Rectangular resonators on silicon-on-insulator with large sensing area for object detection

In this paper we experimentally demonstrate the possibility of detecting an object using a rectangular resonator with a surface area of 200 μm2. The optical biosensor is fabricated on the standard silicon-on-insulator platform, and the object is sensed with the evanescent field that extends from the top of the device. It is possible to detect the presence of the object by measuring the shift of the resonant wavelengths in the transmission spectrum. We compare the performance of the device when it is operated in TE and TM polarization, obtaining superior performance with TM polarization, whereby it achieves a shift of 1.5 nm when a large element is placed on its surface.