# Surface roughness and scattering loss calculation for plasmonic waveguide

#1

Hi,
I am working on hybrid insulator metal insulator(HIMI) plasmonic waveguide at 1550nm wavelength. I have to calculate surface roughness and scttering losses for waveguide. In refrence to that I have some queries:

1. How to model it?
2)How to calculate attenuation losses using lumerical?
2. In case of surface roughness two parameters are defined such as RMS height and correlation length. Is it defined for particular material or for interface. Let say, we are having interface of silver and silica. Then these parameters are to be defined for every material or interface.
3. Mine structure is multilayered where I am having four interfaces, two Ag-SiO2 and two Si-SiO2. Then roughness parameters will be same or different for all four interfaces.
4. SiO2 thickness is only 20nm. So will it support roughness parameter in simulation?

Please share some plasmonic surface roughness example, if available.

Thanks and Regards
Prateeksha

#2

Hi, @prateeksha.s !

1. The notion of losses is quite straghtforward, in that it is just that is lost between an input and output.
It depends on the geometry and structures you are interested in. Is it a waveguide or a scaterrer ?

2. Here is the relevant post, which will be useful for you:
How do I simulate loss due to sidewall roughness?

3. Actually, you are able to define a wide range of structures and surfaces in Lumerical.
The “Surface roughness” can be used in your case and the corresponding information can be found here:

https://kb.lumerical.com/en/ref_sim_obj_surface_roughness.html

1. These are specifics of the structure you are studing since roughness is dependent on the fabrication processes,
in which I am not an expert.