Highly-scalable fabrication of photonic crystal fiber-tip refractive index sensors

We developed a method to easily transfer optical structures from a semiconductor substrate to a fiber-tip facet without the need for glues and preserving the pristine or functionalized condition of the structure surface. An opening is etched on the back of the fabrication wafer and the structure is suspended via breakable support. The transfer is achieved by mechanical contact with the fiber facet. Using a photonic crystal structure designed for high vertical coupling at the Gamma point a reflectance fiber-tip sensor with refractive index sensitivity of 120 nm/RIU has been assembled and could be further functionalized for application in biosensing.