Novel Sensor Design based on Switchable Electromagnetic-Induced Transparency

We can increase detector sensitivity past that of conventional surface plasmon resonance (SPR) detectors by changing the local dielectric environment. Here we demonstrate a novel sensor design that combines SPR detection with a phase-changing element to increase detector sensitivity. Vanadium dioxide (VO$_{2})$ modulates the near-field dielectric environment of the electromagnetically induced transparency (EIT) nanostructures via its insulator-to-metal transition, which shifts the nanostructures' plasmonic response. We obtain a sensor design using three-dimensional, finite-difference time-domain (FDTD) simulations to optimize the dimensions of a gold pi nanostructure exhibiting EIT due to its dipole-quadrupole interaction. To verify our simulations, we use electron-beam lithography to fabricate arrays of optimal structures on VO$_{2}$ films deposited on ITO covered glass by pulsed laser deposition or electron-beam evaporation. We tune the EIT by varying the dimensions of the pi structures, thus changing the strength of the dipole-quadrupole interaction. The resonance of the structures of different separation distances is experimentally verified through measuring broadband white-light transmission while the VO$_{2}$ is thermally modulated.