Design and optimization of compact silicon photonic sensors

Although optical sensors incorporating grating inscribed and etched fibres are now sufficiently mature and well established in the market, however, designs based on more exotic nanowires and photonic crystal fibres are becoming increasingly important and showing much improved sensitivity by accessing a larger evanescent field. Similarly, novel planar design concepts, such as the silicon slot guide-based design is showing even greater promise, allowing the exploitation of well-developed CMOS fabrication technologies for potentially low-cost sensor elements. In compact Integrated Optic format, dielectric slots, plasmonic slots, Mach-Zehnder interferometer, and ring resonators are also emerging as novel photonic sensors. However, high index contrast also makes the modes in such sensing structures fully hybrid in nature and in such a case, full-vectorial rigorous numerical approaches will be necessary for their design optimization. Some selected results for silicon based compact photonic sensors will be presented illustrating the value and potential of the computationally efficient finite element method in such designs.