Abstract
An ultra-compact plasmonic unidirectional wavelength multiplexer/demultiplexer based on slot cavities is proposed and numerically simulated. The structure consists of slot cavities which are etched on either sides of a metal–insulator–metal (MIM) bus waveguide. The cavities capture surface plasmon polariton (SPP) waves at their resonant wavelengths and unidirectionally couples them to the drop waveguide etched parallel to the bus. The structure basically relies on resonance and interference of SPP waves and its functioning is validated through finite element method (FEM) simulations. The simulation results show that the proposed structure functions as expected with a full width at half maximum (FWHM) bandwidth of less than 50 nm, extinction ratio (ER) more than 10 dB, and crosstalk (CT) of less than − 10 dB for the designed wavelengths. The proposed structure holds lot of potential to enhance the miniaturization of ultra-compact integrated photonic circuits for optical signal processing and other related applications.
Highlights
The ability of surface plasmon polaritons (SPPs) to go beyond the conventional diffraction limit has made them potential candidates to realize nanoscale devices which can guide and manipulate light at subwavelength scales
With the rapid advances in nanoscale fabrication technology and easy availability of computational tools backed by affordable computational resources, researchers have been able to propose a variety of SPP based devices using a wide range of materials
The optical path length (OPL) of the fields propagating through the two cavities and combining in the drop waveguide will be the same in the direction in which the SPP wave is propagating in the bus
Summary
The ability of surface plasmon polaritons (SPPs) to go beyond the conventional diffraction limit has made them potential candidates to realize nanoscale devices which can guide and manipulate light at subwavelength scales. With the rapid advances in nanoscale fabrication technology and easy availability of computational tools backed by affordable computational resources, researchers have been able to propose a variety of SPP based devices using a wide range of materials. Multiplexing and demultiplexing being essential operations in communication and signal processing, plasmonic wavelength multiplexer (demultiplexer), which can collect different wavelengths and direct them into a single waveguide (and vice versa) has attracted a lot of interest recently. Such structures based on MIM waveguides have been found to be more interesting due to their advantages stated earlier. By virtue of Helmholtz reciprocity theorem, the proposed demultiplexing structure can function as a multiplexer if the input and output ports are swapped
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