Hi

I did it in COMSOL, for more information you can send a message.

My email: [email protected]

Dear Mohammad Eskandari I am thankful for your help. I have sent you an email.

Looking forward to your response.

Hi Ghaemi,

This is a scattering problem, and is rather easier than the scatterer on substrate, because the background field you need to plug-in the background field setting to solve for the scattered field is just the incident lightwave, as you have a particle in homogeneous medium (the glass).

So, define the incident wave say as Ex=E0*exp(-j*(kx*x +ky*y+kz*z)) for a linearly polarized field along x-axis for instance. If the wave propagates along z-axis from top (towards negative z), then you end up with kx=ky=0 and kz=-emw.k0*ng, where ng is the glass index.

Once solved for scattered field, integrate scattered Poynting vector at the particle surfac i.e., relPoy=emw.relPoavx*nx+emw.relPoavy*ny+emw.relPoavy*nz), and integrate the dissipated power inside the particle, emw.Qrh, and there you have it ! The scattering cross section is simply sigmasc=int(relPoy)/I0, where I0 is incident wave intensity (E0^2/2*Zg, Zg being impedance of the glass), and the absorption cross section is sigmab=int(emw.Qrh)/I0. The sum of these two quantities gives you the extinction.

Hope this helps.

Regards.

Hello Adnane Noual

Thanks for your answer, this seems to be right. If I wanted to put my nanoparticle half in the glass and half in the air, did I have to change the definition of the incident wave?

I am so thankful for your help.

Hi Ghaemi,

Most definitely, in such case the problem becomes slightly different as you have to first (in a first study step, exactly as done in case of scatterer on substrate) compute the back ground filed which is now, not to be confused with incoming light (form a homogeneous medium) !

The Background field is the field existing in the system in absence of the particle (which the latter will then scatter) due to both mediums. In air, this field is sum of incident and reflected field by the glass while in the latter it is the transmitted field (if we assume incident light from air).

Once you compute that field you plug it in the second scattering step to solve for the scattered field (and then compute the quantities you are interested in). I think the scatterer on a substrate (https://www.comsol.com/model/download/563151/models.woptics.scatterer_on_substrate.pdf) will guide here all along.

If you need more assistance, let me know.

Regards.

Hello Adnane Noual Thanks for your answer. I have studied this model and tried to use it for my purpose, but unfortunately when I sweep wavelength instead of azimuthal and polar angles and use frequency domain steps for my study, COMSOL can not compile this model and after hours it crashes.

Do you have any idea what is wrong?

Thanks for you sincere help.

Hi there Katayoon,

Well that sounds like a technical issue at some point you might have encountered/done ?!

I cant tell just like that, I should have a look at your model if you dont mind send it over (saved with no mesh no solutions) to: [email protected]

Kind Regards