Guided resonances on lithium niobate for extremely small electric field detection investigated by accurate sensitivity analysis

Abstract

We present a theoretical study of guided resonances (GR) on a thin film lithium niobate rectangular lattice photonic crystal by band diagram calculations and 3D Finite Difference Time Domain (FDTD) transmission investigations which cover a broad range of parameters. A photonic crystal with an active zone as small as 13μm×13μm×0.7μm can be easily designed to obtain a resonance Q value in the order of 1000. These resonances are then employed in electric field (E-field) sensing applications exploiting the electro optic (EO) effect of lithium niobate. A local field factor that is calculated locally for each FDTD cell is proposed to accurately estimate the sensitivity of GR based E-field sensor. The local field factor allows well agreement between simulations and reported experimental data therefore providing a valuable method in optimizing the GR structure to obtain high sensitivities. When these resonances are associated with sub-picometer optical spectrum analyzer and high field enhancement antenna design, an E-field probe with a sensitivity of 50 μV/m could be achieved. The results of our simulations could be also exploited in other EO based applications such as EEG (Electroencephalography) or ECG (Electrocardiography) probe and E-field frequency detector with an 'invisible' probe to the field being detected etc.

Tunable and high-sensitivity sensing based on Fano resonance with coupled plasmonic cavities

“…Fano resonance, originating from destructive interference between narrow discrete state and broad continuum state, exhibits sharp asymmetric profiles and strong field enhancement 1 – 3 , which may benefit enhanced spectroscopy 4 , optical switches 5 , chemical or biological sensing 6 , 7 , low-loss waveguiding, and nonlinear optical effects. Surface plasmon polaritons (SPPs) can break the classical diffraction limit and enable manipulating light in sub-wavelength structures, so diverse plasmonic nanostructures such as core-shell nanoparticles 8 , ring-disk cavities 9 , nano-slits 10 , 11 and nanowire lattices 12 have been proposed theoretically and experimentally to achieve Fano resonance.…”

“…It is well known that, with variation of nearby or surrounding medium, the transmission and reflection change at fixed wavelength or mode shift can be utilized as sensing signals. In particular, the sharp asymmetrical Fano resonance supported by coupled cavities enables high detection sensitivity in information processing 6 , 7 , 27 – 29 . Lu et al .…”

Fano Resonance on Nanostructured Lithium Niobate for Highly Efficient and Tunable Second Harmonic Generation

“…The localized electric field yields about thirty-six times larger than the incident field in amplitude. In order to quantify this light localization effect, an enhancement factor f opt , which is defined as the ratio of the volumetric electric field amplitude integration in the pattern LN region, with respect to the same quality in the unpatterned LN region, is employed [20]. It denotes as follows:fopt=true∭structured|E(x,y,z)|dxdydztrue∭unstructured|E(x,y,z)|dxdydz…”

“…Combining the EO effect and the second-order nonlinearity, one can build a tunable SHG nanostructure carved onto LN. In addition, the commercially available, nanometrical, thin, crystalline LN on insulator, offer chances to design structures with high field localizations [20,21,22,23,24,25,26]. In terms of obtaining a high field confinement, Fano resonance is an excellent choice.…”

An ultra wideband-high spatial resolution-compact electric field sensor based on Lab-on-Fiber technology

“…In our case, and due to the band-folding phenomenon, two Slow Bloch Modes (SBM) arise for a propagation along the γ direction (i.e. normal incidence) as shown in 36 . The fact that a wide variety of equipment operates at the telecom wavelength ( λ r at 1550 nm) presents an advantage since the structural parameters can be rescaled to set the resonant wavelength λ r .…”