In this page, we use an alternate simulation setup (compared to the standard planewave source based method) with a dipole source to calculate the reflection from a multi-layer stack. In this case, we use an Air - Glass interface. This technique is appealing because it allows the reflection at all angles to be calculated in a single simulation. Another advantage is that all the simulation boundaries are set to PML, which can lead to better performance for angles at or near the critical angle.
Simulation setup
The above figure shows the simulation setup of dipole_2layer.fsp. The Air - Glass interface is visible, along with the dipole source (blue circle) and profile monitor (yellow line). A profile monitor is located just below the stack. Forward and backward far field projections are calculated from the monitor. The reflection can be calculated by dividing the backward projection by the forward projection. One simulation per polarization is required.
Advantages:
- One simulation gives R and T at all angles
Disadvantages:
- This technique can only be used for unpatterned slab, not for gratings
- As the stack becomes larger, very wide simulation spans may be required
Results
The script dipole_2layer.lsf will run two simulations, and then calculate the analytic solution. The simulated and analytic reflection and transmission vs. incident angle are plotted for both polarization.
