Learning Forum

[SAURAV GAUTAM]

Hi,

I simulated a cubic structure with cylindrical hole with plane wave source above surface. The electric field result are not uniform radially. i cannot find the cause of two major spots as shown in attached figure.

i also tried changing polarization angle to 90 and averaging absolute E values. Result is 4 spots.

is there any explaination of this as it seems results should be circular uniform pattern

 

.

thanks

[Guilin Sun]

This is the physics that when a uniform plane wave illuminstes tiny periodic objects, the intensity on the object surface will not be uniform. As you may know, anything perturbes the plane wave nature, eg, non uniform material will cause wavefront distortion. 

[SAURAV GAUTAM]

Thank you,

The cylindrical hole is symmetrical in both x and y direction. may i know why could be the cause of wavefront distortion and is there any way to check the calculation going on in simulation..

[Guilin Sun]

Because now it is sub-wavelength light-matter interaction, and the material is not uniform. If you simply use a plate without any nano structure it will be perfect plane wave. Please check.

[SAURAV GAUTAM]

so the hole at centre is making it non uniform?

[Guilin Sun]

You are right! if you disable the hole it will show the plane wave nature correctly.

[SAURAV GAUTAM]

 

thank you

the simulation is non periodic with PML boundaries and single hole.

and when i placed the monitor above source to measure reflectance , i got uniform concentric ring shaped result.

[Guilin Sun]

For non-periodic with PML, you cannot directly use plane wave. Instead, you can use TFSF source. and the intensity will not be uniform when the hole is there. This is the physics for nanophotonics.

[SAURAV GAUTAM]

thank you