Reflection cross section



i am simulating a periodic nanoantenna sensor, the sensor consists of the gold disk on top of a silica disk on a substrate. i measure the reflection by the upper monitor at background index 1.33 and another simulation at backgroundindex 1.34 to calculate the sensor sensitivity = change in resonance wavelength / change in Refractive index (background index) . the simulation attached seems to resonate correctly but the graph has ripples compared to same simulation on CST

115) Mushrom 1.33 groundplane Palik gold - full range.fsp (252.8 KB)


Dear @hamada

I think we discussed your simulations already here, however I tried to provide you how you can deal with this case here again.

These simulations are taking a long time which is the nature of your simulation. This is because you have a gold disk that acts like a high-Q cavity and stores the field for a long time.

Please see the edges of your gold disk below, they tend not to decay and simulation takes a long time:

I did some modification and ran it for a relatively long time and here is the plot that I got:

I have my simulation file attached:

Mushroom_Modified.fsp (253.7 KB)

Here are a few things to do:

  1. Use a finer mesh and make sure that results converge.
  2. Use a higher number of PML layers
  3. Use a longer simulation time
  4. Use a longer pulse in time domain and run simulation for wavelengths span of 3150-3250.