Terahertz multiparameter sensors based on frequency selective surfaces coupled to subwavelength fibers

We propose using frequency selective surfaces as resonant sensors for simultaneous measurement of several optical properties of thick films placed in contact with a flat part of the device. Changes in refractive index, losses and thickness of a film can be measured by detecting changes in the spectral position, and amplitude of the transmission peaks in the THz fiber spectrum. As an example, our simulations show 0.16 GHz / μm sensitivity to changes in the film thickness.