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What is the physical meaning of scaling factor in PML setting?

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Hi all,

I am currently using pml to absorb light to prevent back refletion. In my simple model, I incident the light by using a port to a mirror (using perfect electric conductor BC), and let the reflected light to enter the pml behind the port. Periodic boundary conditions are used on the sides of the rectangles, and scattering BC is used at the end of the pml. Before entering the pml, I also have a boudary to integrate the poynting vector perpendicular it.

I expect, if I do it correctly, all the light gets reflected by the mirror and I will get all of the incident light. But I also realized that there may be significant reflection if the light enters the pml with a very large angle. I started to tune the parameters in the pml settings and found that when I am using rational stretching and a very large scaling factor (~200), the results are pretty good. The settings worked well in another slightly more complicated model which I used to collect the light by using port's diffraction orders.

However, I have no idea what I have been done phyiscally by tuning the scaling factor in pml. Can anyone help me with this?

Many thanks!

0 Replies Last Post 2019年8月15日 GMT-4 上午7:00
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