Fabry-Perot Resonance Effect Research Articles

Multiwavelength absorption switching based on the metal-dielectric-metal multilayer Kerr metamaterial

In this paper, quintuple-band absorption switch has been demonstrated and studied. Finite-difference time-domain simulations indicate the absorption originated from localized surface plasmon polaritons and Fabry–Perot resonance effect. Quintuple-band plasmonic perfect absorption with maximum absorption of 99.8%, 86.2%, 99.9%, 95.8%, and 97.8% at the resonance wavelength of 635 nm, 694 nm, 915 nm, 1125 nm, and 1345 nm, respectively. We calculate the sensitivity of the five modes is about s 1 = 74 n m / R I U , s 2 = 376 n m / R I U , s 3 = 518 n m / R I U , s 4 = 512 n m / R I U , and s 5 = 7 98 n m / R I U (RIU is the refractive index unit). Angle and polarization independent of the quintuple-band absorption are also investigated. Moreover, by adjusting the pump light on and off, absorption ratios of 3.9, 10.3, 3.8, 3.4, and 6.8 have been achieved. Besides, the proposed multiwavelength absorption switching has excellent absorption stability and polarization tolerance. We believe the proposed structure can find potential applications in the fields of multiband sensor and all-optical modulation.

Angle-invariant eye-friendly color filter capitalizing on a multi-layer nano-resonator integrated with highly reflective/absorbing media.

Color filter with a combination of excellent angle insensitivity and high near-infrared shielding absorption is essential to broaden its practical application of harsh environment. However, there are few attention on the near-infrared absorption of color filter, prominent to the protection of human eyes in some special application scenarios. Herein, we propose and develop a dual-function color filter composed of four-layer silicon/titanium planar nanostructure that integrates with both angle-invariance and near-infrared shielding. The proposed color filter enables the creation of three reflective color primaries of cyan, yellow, and magenta (CYM) employing a combination of Fabry-Perot resonance and anti-resonant effect with the tuning of silicon thickness. The created reflective colors are less sensitive over a wide angle of incidence up to 60°, where the center wavelength of optical spectra is shifted by below 1.8%. Besides the angle-invariant performance, the color filter can effectively shield near-infrared light with a 70% average absorption under normal incidence. Moreover, this filter's thermal stability at 500°C demonstrates its feasibility for extreme environments. The demonstrated color filter is suitable for architectural decorative coatings and outdoor protective coatings in some harsh environment with strong near-infrared radiation, such as glass smelting, steel forging, and long-term sunlight exposure.

Design and energy analysis of tunable nanophotonic infrared filter based on thermochromic vanadium dioxide

In this work, a mid-infrared tunable nanophotonic filter is designed by placing a silicon spacer layer between two nanometric vanadium dioxide films on a thick infrared-transparent substrate. Transfer matrix formulation incorporated with the ray-tracing method is used for the optical modeling, and a transmittance peak near 4 µm wavelength is achieved based on Fabry–Perot resonance effect. Thermochromic vanadium dioxide allows the filter to be switched between a semi-transparent state when cooled below its phase transition temperature and an opaque state when heated above its phase transition temperature. The underlying mechanism is elucidated by calculating the total phase shift of electromagnetic waves through the spacer layer, and the effect of layer thicknesses on the spectral transmittance peak is discussed. The filter can find potential applications in energy dissipation where it can actively promote or suppress radiative cooling, and in thermal camouflage where the apparent temperature of a hot surface through the filter can be greatly reduced. Detailed energy analysis is conducted for both applications with the proposed tunable filter, whose structure is further optimized through the thicknesses of the thin-film layers to achieve maximum performance.

Ultra-broadband perfect solar energy absorber based on tungsten ring arrays

Metamaterials play a crucial role in the research of broadband absorbers. In order to achieve broadband and efficient absorption of solar energy, a novel solar energy absorber based on tungsten ring array is proposed in this paper. The results of numerical analysis show that the absorption efficiency of the absorber is over 90% at 300∼2000 nm, the average absorption efficiency is 96.2%, and the absorption peak is 99.9%. Broadband absorption can be attributed to the excitation of plasmon and Fabry–Perot resonance effect on the surface of metal-insulator-metal. In addition, thanks to the high symmetry of the structure, it is relatively independent of incident angle and polarization angle. In the future, the absorbent will have a promising application prospect in the fields of solar energy utilization, photothermal conversion and infrared detection.

Optical Transmission Properties of Si3N4 Add-Drop Micro-Ring Resonator Induced by a Fabry-Perot Resonance Effect.

To resolve the problem of miscellaneous peaks and improve the accuracy of data processing in micro-ring resonators (MRRs), we propose an optical transmission model based on a Fabry–Perot (F-P) resonance effect in a Si3N4 add-drop MRR-waveguide structure, which is analyzed using a coupled mode theory and stationary interference method. The analysis indicates the experimentally obtained miscellaneous peaks are mainly induced by the multiple reflections between the two end grating couplers, which form a F-P cavity. In addition, an anti-reflection film on the interface of the grating couplers is proposed to reduce the F-P resonance effect. This work could be useful to analyze optical transmission properties of other MRR-based structures.

Numerical study of an ultra-broadband, wide-angle, polarization-insensitive absorber in visible and infrared region

An ultra broadband high-performance metamaterials absorber is designed based on the Fabry-Perot resonance effect and hybrid coupling theory. In this paper, we use the numerical method to analyze the absorption characteristics of the absorber under the conditions of wide band, different polarization states and large angle oblique incidence. The results reveal that the absorption band of the absorber is 300 nm–3000 nm, and its average absorption rate exceeds 93%. In addition, the absorptivity of the absorber is less affected by the polarization angle and incident angle of the incident light. The physical mechanism of wide-band high-absorption is analyzed, which is mainly caused by Fabry-Perot resonance, surface plasmon resonance, local surface plasmon resonance and the hybrid coupling among them. The proposed metamaterial absorber is expected to play a role in invisible devices, solar cells and other fields owing to its wide absorption bandwidth, high absorption, independent to polarization and stable at wide-angle of incidence.

High-performance terahertz vortex beam generator based on square-split-ring metasurfaces

Generating a vortex beam is a fundamental task due to the potential applications in wireless communication. Here we propose a kind of high-performance terahertz vortex beam generator with several topological numbers based on the square-split-ring metasurfaces. Via the Fabry-Perot resonance effect of the structure, the transmittance of an orthogonal polarization mode could be remarkably enhanced. We use a Laguerre-Gaussian (LG) mode for illustration and then simulate the far-field propagation of the LG beam by using phase superposition of focusing lens and vortex phase plates. The theoretical and simulation results agree well, which implies a bright application prospect.

Giant Pockels effect in an electrode-water interface for a “liquid” light modulator

We report the development of a light modulator using the Pockels effect of water in a nanometer-thick electric double layer on an electrode surface. The modulator comprises a transparent-oxide electrode on a glass substrate immersed in an aqueous electrolyte solution. When an optical beam is incident such that it is totally reflected at the electrode-water interface, the light is modulated at a specific wavelength with a near-100% modulation depth synchronized with the frequency of the applied AC voltage. This result was reproduced by a calculation that assumes a change in the refractive index of −0.1 in a 2-nm electric double layer and of −0.0031 in a 30-nm space-charge layer formed at the interface between the electrolyte aqueous solution and the transparent electrode. This is the first report of an optical modulator that uses the interfacial Pockels effect of a material that does not allow for the Pockels effect in the bulk. The principle of giant optical modulation is explained by invoking the large Pockels coefficient of interfacial water and a Fabry–Perot-resonance effect in the transparent thin-film electrode.

Dual-Band Infrared Perfect Absorber Based on a Ag-Dielectric-Ag Multilayer Films with Nanoring Grooves Arrays

In this paper, we demonstrate a dual-band metamaterial perfect absorber based on a Ag-dielectric-Ag multilayer nanostructure. The structure of top metal film covers nanoring grooves array. A dielectric layer has a function of confining electromagnetic fields. Theoretical analysis shows that two absorption peaks (1059 nm and 1304 nm) with the absorption of 99.2% and 99.9% have been achieved, respectively. The physical origin of perfect absorption peaks are related to the Fabry-Perot resonance effect and localized surface plasmon resonance (LSPR) of the nanoring grooves. Its perfect absorption and resonance wavelength can be well regulated by adjusting the relevant structural parameters. Additionally, the absorber demonstrates good operation angle-polarization-tolerance at wide incident angles (0–60°). We believe that our design has a promising application in plasmon-enhanced photovoltaic, optical absorption switching, and modulator optical communications in the infrared regime.

Plasmonic absorber and nanosensor assisted by metal films coupled with hexagonal holes array

Spectral features and nanosensing of hexagonal array of holes with a circular cross section metamaterial are investigated by performing the three dimensional finite difference time domain simulation. Fabry-Perot resonance effect and localized surface plasmon resonance of the hexagonal holes array generate absorption peak under normal incidence. Besides the geometrical parameters of the nanostructure, absorption characteristics strongly depend on the refractive index of environmental or dielectric layer. The results of this paper may have potential application not only in plasmonic absorber but also in nanosensor.

Extraordinary optical transmission through a rectangular hole filled with extreme uniaxial metamaterials.

This Letter presents a theory of extraordinary optical transmission (EOT) through a rectangular hole filled with the extreme uniaxial metamaterials with infinite longitudinal components of permittivity (ϵz) and permeability (μz). We demonstrate theoretically and numerically that a number of high-order transverse electromagnetic (TEM) modes can be supported by such a structure, and that, more interestingly, their normalized transmittance can be remarkably enhanced due to the Fabry-Perot resonance effect. A set of illustrative examples has been provided to demonstrate that such an EOT property could be explored for the purpose of subwavelength-resolution imaging.

All-optical diode of subwavelength single slit with multi-pair groove structure based on SPPs-CDEW hybrid model

All-optical diode is the most basic photonic device in integrated optical circuits. It is of great significance to develop a modulated optical diode for preparing complex optical circuits in the near future. However, there are few studies on constructing all-optical diodes in subwavelength metal micro-nano structured devices based on the hybrid model of surface plasmon polaritons (SPPs) and composite diffracted evanescent wave (CDEW). In fact, most of the researches have been focusing on how to effectively enhance the unidirectional nonreciprocal transmission of the optical diode and improve the extinction ratio. According to SPPs-CDEW hybrid states, in this paper we put forward a novel method of designing an optical diode and its structure. The structure consists of a subwavelength single micro-nano slit surrounded by symmetric multi-pair grooves on a silver film. First of all, on the basis of the single slit structure of the silver film, the pairs of the groove structures are etched on both sides of the silver film: the positions and quantities of the grooves on the top and bottom surfaces are asymmetric. Then combining with an effect similar to Fabry-Perot resonance effect inside the micro-nano slit, the function of beam unidirectional transmission is achieved by controlling SPPs through changing the geometric parameters of the structure. Furthermore, in order to realize unidirectional nonreciprocal transmission, by means of theoretical derivation and the finite element method (FEM), in this paper we analyze the transmission enhancement phenomenon of single slit-symmetric pair of groove micro-nano structure, discuss the physical mechanisms of transmission enhancement and weakening, and also give the far field transmission spectrum of the normalized transmission changing with the distance between slit and pair grooves. The results obtained from the rigorous theoretical formula are in excellent agreement with the numerical results obtained by using FEM. Finally, as the position and number of the pair grooves are precisely determined by this transmission spectrum, the optimized all-optical diode structure, of which the unidirectional transmission is effectively enhanced and the extinction ratio of the optical diode is improved, is achieved with five pairs of enhanced transmission grooves formed on the top surface of the Ag film and six pairs of weakened transmission grooves formed on the bottom surface. The maximum extinction ratio reaches 38.3 dB, which means that the forward transmittance is 6761 times the reverse transmittance, i.e., it increases 14.6 dB over the result from previous theoretical work. And there appears a 70 nm wavelength band width (20 dB) in the operating wavelength 850 nm. The proposed optical diode has the advantages of simple structure, wide working bandwidth, easy integration, and high coupling efficiency. The research of the optical diode is valuable for the potential applications in optical signal transmission, optical integrated optical circuit, super-resolution lithography and other related fields.

Absorption property and nanosensing via double metal films with rectangle holes array

A theoretical investigation of plasmonic absorption and nanosensing based on a three dimensional nanostructure is presented. The structure consists of double metal films covered with rectangle nanoholes array. A dielectric layer is located between the double metal films with the function of confining electromagnetic fields. Optical absorption properties of the designed nanostructure are investigated by finite-difference time-domain method, obvious peaks appear in the absorption spectra is due to the Fabry–Perot resonance effect and localized surface plasmon resonance of the rectangle nanoholes. The absorption spectra dependence on the environmental and dielectric layer refractive index, which makes it an outstanding candidate for nanosensing. The results of this study may have potential application in absorption switching and nanosensors.

Numerical study of plasmonic filter based on metal-insulator-metal waveguide

A novel nanometeric plasmonic filter comprised of double-sided eight stub resonators side-coupled with a metal-isolator-metal waveguide is proposed and demonstrated numerically by the finite element method. The numerical results show that the four transmittance peaks in a transmission spectrum range from 400 nm to 2000 nm can be achieved due to the electromagnetically-induced-transparency-like spectral responses between every two adjacent stub resonators with detuned cavity length. Based on the magnetic field distributions from the two dimensional model, the physical origins of transmittance peaks and dips are clarified by phase analysis of Fabry-Perot resonance effect. In addition, the central wavelengths of transmittance peaks can be tuned by adjusting the cavity length of each stub resonator, which means the waveguide filter could be utilized to develop ultracompact and tunable narrowband photonic filters for high integration.

Efficient Broadband Transmissive 90° Polarization Rotation Using a Single Layer of L-shaped Particles Inside a Glass Cube

We realize 90° polarization rotation with both high polarization conversion efficiency and broad bandwidth by using a single layer of L-shaped particles inside a glass cube. The simulation results show that Fabry-Perot resonance effect enhances the transmission for both co-polarization and cross-polarization light in the L-shaped layer. And the co-polarization electric field component has been suppressed in the far field because of the destructive interference. The simulation results also show that the spectral band of peak polarization rotation can be shifted by changing the size parameters. This broadband polarization rotation mechanism may be very useful in designing polarization rotators.

Acoustic focusing of sub-wavelength scale achieved by multiple Fabry-Perot resonance effect

It is demonstrated that a novel design of a multi-branch structure can converge plane acoustic waves to a focal region of sub-wavelength scale. The structure consists of multiple sub-wavelength apertures; each has length equal to the integer times that of the shortest aperture. The periodicity length of the inlet array is selected equal to the length of the structure, inducing a cooperation between the surface resonances and the Fabry-Perot (FP) resonances in apertures. The design allows FP resonances to exhibit in all apertures simultaneously, hence a multiple FP resonance is achieved. The generated evanescent waves are amplified effectively, and the acoustic focusing of sub-wavelength scale is realized within a wide frequency range, with an approximate maximum transmission gain of 7 dB.

Light absorption enhancement in thin-film solar cells by embedded lossless silica nanoparticles

Embedded silica nanoparticles in thin-film silicon solar cells have some advantages over metal nanoparticles in enhancing optical absorption of silicon such as no loss, better compatibility with antireflection coating and extremely low dangling bond densities and interface recombination velocities. To the best of our knowledge, we have carried out the first systematic study of optical absorption enhancement with silica nanoparticles of different radii, array periods and depths in the silica substrate with the finite-difference time-domain method, and we have obtained the optimum values of the nanoparticle parameters. We discuss the physical mechanism of the optical absorption enhancement in detail and attribute the enhancement to the superposition of the particle scattering effect and the Fabry–Perot resonance effect.

Plasmon induced transparency in a dielectric waveguide

A classical effect of electromagnetically induced transparency (EIT) is demonstrated in a dielectric slab waveguide at visible frequencies. Two nano-sized elliptical silver particles are placed inside the waveguide core layer, and their localized plasmonic resonances are utilized to obtain bright and dark states. The destructive interference between the two resonance paths leads to an EIT-like transmission spectrum of the waveguide. The contrast between the transmission peak and dip can be further enhanced by incorporating the Fabry-Perot resonance effect. The influence of Joule loss on the EIT performance is also investigated.

Reflex optical sensor based on dual metal gratings with high angular sensitivity

An interesting reflection phenomenon in a dual metal grating (DMG) structure is studied, which is related to the competition between Fabry-Perot (F-P) resonance effect and evanescent-field coupling effect inside the gap between the two composing single metal gratings. This competition leads to high angular sensitivity in response to the refractive index variation of the sample solution in the gap. A reflex optical sensor with high sensitivity based on DMG for detecting the change in refractive index is proposed and its performance theoretically is discussed.

Interference and horizontal Fabry-Perot resonance on extraordinary transmission through a metallic nanoslit surrounded by grooves

The debate on the underlying physics of the extraordinary optical transmission (EOT) through a metallic nano-slit surrounded with periodic grooves is largely resolved. We clarify that the EOT originates from the interference between the slit modes excited by the incident light and by the groove-generated surface plasmon polaritons modulated by the horizontal Fabry-Perot resonance effect due to the surrounding grooves. The quantitative model derived will greatly simplify the design of such structures.