Metal-Dielectric-Metal Plasmonic Taper for 3D Nanofocusing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for squeezing light into a subwavelength scale face challenges such as low coupling efficiency and side lobes, with existing approaches either providing deep subwavelength dimension only in one direction or requiring complex coupling configurations, while efficient light coupling from dielectric waveguides into plasmonic waveguides remains unsolved.
Innovation Solution
A nanofocusing system involving a dielectric waveguide and a metal-dielectric-metal (MDM) plasmonic taper, where light is efficiently coupled from a dielectric waveguide into a MDM waveguide, with the taper reducing light dimensions in both horizontal and vertical directions to achieve three-dimensional nanofocusing, utilizing a 3D MDM plasmonic waveguide with a large dielectric constant contrast for low loss and high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If light is directly coupled into a deep subwavelength circular or square aperture, then the aperture size is reduced to subwavelength scale, but the coupling efficiency becomes very low
Solution Approach 1:
The patent introduces a tapered plasmonic waveguide as an intermediary structure between the light source and the subwavelength aperture. This waveguide gradually transforms the light mode from a large-mode-size input to a small-mode-size output, enabling efficient coupling into the subwavelength aperture without direct coupling
Solution Approach 2:
The patent employs a tapered waveguide structure where the geometric parameters (width, height) change continuously along the propagation direction. This gradual parameter change enables adiabatic mode transformation, allowing the light to adapt to the changing mode size without reflection or loss, thereby maintaining high coupling efficiency
2Volume of moving object
If deep subwavelength confinement by metal is applied in multiple directions, then the light is squeezed into a smaller volume, but the cutoff frequency is imposed and transmission becomes extremely small
Solution Approach 1:
The patent applies different structural characteristics to different regions of the waveguide. The input region has larger dimensions for efficient light coupling, while the output region has subwavelength dimensions for tight confinement. The tapered transition region smoothly connects these two regimes, allowing the system to achieve both high transmission and small output size
3Illumination intensity
If resonant optical antennas shorter than one-half the wavelength are used, then the field is enhanced in the antenna feed gap, but low coupling efficiency and side lobes constitute significant drawbacks
Solution Approach 1:
The patent converts the harmful effect of mode mismatch (which causes reflection and loss) into a beneficial adiabatic transformation process. By using a tapered waveguide with gradually changing dimensions, the mode evolution is made smooth and continuous, transforming what would be a abrupt discontinuity into a controlled, efficient coupling mechanism
4Length of moving object
If existing plasmonic approaches are used to squeeze light subwavelength, then subwavelength dimension is achieved in one direction, but deep subwavelength dimension in both directions is not provided
Solution Approach 1:
The patent extends the confinement from one dimension to two dimensions by employing a tapered waveguide that reduces both the width and height simultaneously. This three-dimensional tapering enables the light to be confined in both transverse directions, achieving deep subwavelength confinement in x and y directions rather than just one direction
5Productivity
If complex coupling configurations are used to achieve efficient light coupling, then coupling efficiency improves, but device complexity increases
Solution Approach 1:
The patent merges the coupling function and the waveguide function into a single integrated tapered structure. Instead of using separate coupling elements and waveguides, the tapered waveguide itself performs both functions: it couples the light from the input waveguide and simultaneously guides it to the subwavelength output, thereby simplifying the overall device structure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves high efficiency in coupling light into a nanoscale spot, with a spot size of 20 nm-by-20 nm, increasing light intensity and enabling applications in optical interconnection, sensitive modulators, and optical lithography with reduced propagation loss and surface scattering.
Implementation Method 1
confining the light in a first dimension by coupling the light from the dielectric waveguide into a metal-dielectric-metal waveguide
Implementation Method 2
squeezing in a second dimension the light confined in the first dimension by passing the light through a taper in the metal-dielectric-metal waveguide
Implementation Method 3
photons are converted into surface plasmon polaritons and propagate along the surface of a tapered nanowire or waveguide
Data Source
AI summary
A nanofocusing system includes a dielectric waveguide having two opposing ends; and a metal-dielectric-metal layered waveguide having two opposing ends optically aligned at one end with one end of the dielectric waveguide, wherein the metal-dielectric-metal waveguide tapers in at least one dimension from the aligned end of the metal-dielectric-metal waveguide towards the opposing end, wherein light travelling through the dielectric waveguide is funneled into the dielectric layer of the metal-dielectric-metal waveguide, squeezed by the metal-dielectric-metal waveguide taper, and exits the metal-dielectric-metal waveguide as nanofocused light.