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By combining a Fabry–Perot (FP) cavity with a slot cavity, a compact filter structure is proposed. The peak resonance wavelength is determined by applying the FP resonance condition of the FP cavity. The relationship between filtering wavelength and cavity parameters is investigated. The results show that the filtering wavelength can be manipulated by changing the nanocavities' parameters. By using the finite difference time domain method, the theoretical predictions are confirmed. An intersection structure for nanoplasmonic waveguides is proposed and designed by utilizing two perpendicular filters. In addition to having compact dimensions, the proposed arrangement provides higher throughput and low cross talk. The proposed structure can be useful for designing compact integrated nanoplasmonic circuits.

Here by introducing an I-shape structure to break the symmetry of a thin metallic film, the contributions of Fabry–Perot (FP) resonance-like modes and surface plasmon polariton (SPP) resonance-like are determined. The finite difference-time domain (FDTD) simulation is utilized to provide a clear picture of the electromagnetic field distribution and transmission profile. The FP matrix method is employed to specify the contribution of FP resonance. Some of the predicted resonances of the FP matrix method coincide with the simulation result which is labeled as FP resonance-like modes. The remaining resonance modes in transmission profile are considered as SPP resonance-like modes. Our results provide explicit evidence that both FP resonator modes and SPP resonance are responsible for extraordinary optical transmission (EOT) through a subwavelength aperture.

The enhanced light transmission through an I-shape aperture is studied by simulation and theory. The transmission profile due to microcavities created in the entrance and exit of the aperture was modified and new peak was observed. By introducing a new formula the refractive index of layers is defined. The Fabry–Perot matrix method is employed to explore the role of Fabry–Perot resonator effect in modified slits, especially I-shape slit in the scope of this work. And the peaks correspond to this effect are determined. The effect of microcavity surface Plasmon polaritons is explored respectively. Both microcavity surface plasmons and Fabry–Perot resonator contribute in transmission enhancement and consider as the origin of extraordinary transmission for unsymmetrical slits.

By utilizing a Fabry-Perot (FP) cavity and slot cavities, a compact filter with functionalized characteristics is designed. Its filtering wavelength can be manipulated by changing resonance conditions of the FP cavity and nanocavities’ parameters.

By utilizing a Fabry—Perot (FP) nanocavity adjacent to T-shaped gap waveguide ports, spectrally selective filtering is realized. When the wavelength of incident light corresponds to the resonance wavelength of the FP nanocavity, the surface plasmons are captured inside the nanocavity, and light is highly reflected from this port. The resonance wavelength is determined by using Fabry—Perot resonance condition for the nanocavity. For any desired filtering frequency the dimension of the nanocavity can be tailored. The numerical results are based on the two-dimensional finite difference time domain simulation under a perfectly matched layer absorbing boundary condition. The analytical and simulation results indicate that the proposed structure can be utilized for filtering and splitting applications.

Surface plasmon (SP) microcavity recently has been proposed to enhance transmission through a subwavelength slit. Here we employed Fabry-Perot matrix method to predict the transmission profile of the structure. The result show good agreement with simulation result based on finite difference time domain (FDTD) method. The calculation shows that the SP microcavity standing waves and the Fabry-Perot resonance mode are responsible for transmission enhancement. For layered slits FP matrix method is a powerful method for prediction transmission behaviors.

By embedding a nanocavity adjacent to one or both of slits in a subwavelength double-slit structure, frequency selective propagation through the slits is demonstrated. When the incident light wavelength corresponds to the cavity resonance mode, the electromagnetic wave passing through the slit will be trapped within the nanocavity. Therefore, the double slit operates as a single slit and light propagation is solely allowed through the partner slit. These wavelengths are determined by applying the Fabry—Perot resonance condition for the nanocavities. Various geometrical structures result in different effective refractive indexes. Thus, the effective refractive index and consequently the attenuation wavelength can be adjusted by choosing the appropriate parameters of the nanocavity. Our theoretical predictions are in good agreement with 2D finite-difference time-domain simulation.