Currently I am simulating scattering spectra for nano-disk in COMSOL. My aim is to obtain maximum scattering coefficient with in the wavelength range 550nm -800nm.
To maximize the scattering co-efficient how to formulate the objective function, constraint variable etc.?
I suppose, you should use the disk material with high reflection constant in this wavelength range.
Just make it as large as possible, high order modes always scatter more than lower harmonics. But I assume you have some restrictions on size. So i suggest to set up a parametric space of geometric parameters and analyse scattering within this space.
For COMSOL, you may apply a parametric sweep in which you can vary the geometric structure (such as resonator radius , height, etc.) of the simulation object and monitor the outputs of your interest (such as scatter cross-sections, absorption cross-sections, ect). That is a straight forward but might be time-consuming way (for computers to calculate) to achieve the optimized structure design.
For some rough predictions, perhaps generally the larger of the scatterer, the higher scatter amplitude will be expected.. However, I guess you may have some other perhaps resonant spectral conditions to be satisfied? The material (plasmonic / dielectric) may also be an issue.
Beside FEM method, FDTD method may also work. If helpful, you may access the following URL for the Lumerical simulations on scattering.
https://kb.lumerical.com/en/layout_analysis_resonators_modal.html
https://kb.lumerical.com/en/particle_scattering.html
I hope it will be helpful. Good luck. ( :
Thank you all for your helpful suggestions. At present I am carrying out simulation with silicon nano-disk (un-optimized structure) with the aim to maximize scattering.
As I do not have access to a proper workstation, so I am searching for a mathematical approach instead of parametric sweeping etc. to maximize scattering co-efficient.
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