Discussion Forum

Hi there,

I've been trying to simulate graphene plasmonic (GP) giuded wave with a 2D graphene layer cladded with air domain (relative permittivity = 1), but can't get the dispersion relation I expected.

Model is built with 2D geometry, with RF module (emw) for physics with 'Three-component vector'. Air domain is set with built-in material properity; graphene is set as 'Surface Current Density' by setting current density as below:

Js0,x = sigma_graphene*emw.Ex
Js0,y = 0
Js0,z = sigma_graphene*emw.Ez

'sigma_graphene' is the conductivity of graphene, a function of frequency with unit [S/m].

Top and bottom boundaries are set as 'Perfect Electric Conductor' (PEC) to simulate cladding is infinited extended along y axis. Left boundary is set as input port, using numeric type of port; right boundary is set as output port, set as numeric port as well but excitation of port is off.

Step 1 and 2 of study are 'Boundary Mode Analysis'. Since GP have extreme light confinement, I set the 'Search for modes around' = 25, a very large effective mode index and 'Desired number of mode' = 1. But error 'No eigencalues found' pops out, can't find mode satisfy the boundary. I've tried adjusting 'Search for modes around' from 10~50 but still can't find the correct mode I want.

Also I have built the mesh much finer than 'Extreme Fine Physics-Controlled mesh', so I think mesh setting is not the problem here. Did I miss any setting or got anything wrong? Most of the settings are refer from COMSOL Example 'Dielectric Slab Waveguide', maybe some of the settings are not suitable for caucluating GP and I misues them.

Thanks for your help!