Optimization of Optical Multilayers for Biological Sensing Using Bloch Surface Waves*

We developed an interactive computer program in Python that optimizes the design for multilayer arrangements that exhibit Bloch Surface Wave behavior, which can be used to create a cheap and precise biodetector. A Bloch Surface Wave is a guided electromagnetic wave which is bound to the surface of one of the layers. When a Bloch Surface Wave occurs, the reflectivity of the system is lowered significantly, potentially even to zero, causing an easily observable pattern in the light reflected off the optical multilayer system. Using the Bloch Surface Wave phenomena, it is possible to detect very fine changes in material width or optical index, allowing for the detection of events such as antigen-antibody reactions. The computational simulations of the generated multilayer arrangements show sensitivities in terms of degrees per RUI (Refractive Index Unit) at an incident light wavelength of 650 nanometers, and the program can create a multilayer arrangement for any desired incident light wavelength. Future exploration of the multilayers designed this way is warranted, such as the behavior of multilayers with multiple Bloch Surface Waves present.