Photonic Structures Based on Slot Waveguides for Nanosensors: State of the Art and Future Developments

This review presents the state-of-the-art of Bio-Chemical nanosensors based on silicon Photonics. SOI (Silicon on Insulator) technology offers a number of guiding structures such as slot, rib, strip and silicon wire waveguides. We discuss many sensing principles employed in optical detection, such as absorbance, reflectance, fluorescence, chemiluminescence, bioluminescence and refractive index (RI) measurement. The integration of ultra high sensitive photonic waveguides in interferometer architectures (e.g. Mach Zehnder interferometer) and resonant architectures (e.g. ring resonator, Fabry Perot cavity), allow the detection of ultra low traces of chemical/biochemical analytes and gases. Sensing performance of photonic nanosensors based on silicon Photonics are very attractive, exhibiting ultra high sensitivity and low limit of detection (i.e. pg/mL, pmol/L). Intensive research in this field is motivated by broad applications of photonic sensors in healthcare, environmental monitoring, homeland security, food industry, pharmaceuticals, which require sensitive and rapid analytical tools.