Optical Fiber-Coupled Waveguide Grating Chip Sensor Fabricated by Ultraviolet Nanoimprint Lithography

A novel optical fiber-coupled waveguide grating chip device based on Fano resonance effect is proposed and demonstrated for the first time, to the best of our knowledge. It is fabricated by ultraviolet nanoimprint lithography (UV-NIL), with the advantages of low-cost and easy mass production. Such a device can perform multifunctional sensing such as refractive index (RI) and pressure because the variations of the effective RI of the guide mode and the grating period will cause the resonant wavelength shifts under the change of external parameters. Through experimental verification, a RI sensitivity of 59.29 nm/RIU and a pressure sensitivity of 0.89 nm/MPa, a copper ion concentration detection sensitivity of 3.40 pm/ $\mu $ M are achieved, respectively. Furthermore, the chip sensing function is realized, and each arrayed sensing unit is interrogated through optical fiber scanning. This kind of optical fiber-coupled waveguide grating chip sensor can not only realize array sensing but also measure various physical and chemical parameters. It could find important applications in biochemical and industrial fields.