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significant reflection from PML boundary of different materials
Posted 6 avr. 2014, 23:43 UTC−4 Version 4.3b 1 Reply
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Hi,
I have a problem implementing PML boundary for my model. I'm doing an EM frequency domain solution and I have a Gaussian source of 780 nm in wavelength propagating in air incident on 5 microns thick silicon. The rectangular simulation region is enclosed with 2 x wavelength thick PML region. I have the materials for the PML region behind the silicon slab set as silicon as well. The meshings are wavelength/32 for Silicon region (including the PML behind it) and wavelength/16 for everything else. For some reason I still get standing wave inside the silicon although it is absorbed by the PML. I tried messing with the scaling factor but it does not do anything. Does anybody know a way around this problem? I'm aware that increasing the silicon thickness to the point of complete absorption will solve this, but it is not an option due to limited memory (besides silicon at 780nm has a very large absorption depth).
I also tried with setting the whole simulation region's material to silicon, and it still shows reflection in the PML boundary. It seems like the PML region does not work for different materials rather than air.
I also attached the file for the simulation setup.
Any help is greatly appreciated. Thank you
Rico
I have a problem implementing PML boundary for my model. I'm doing an EM frequency domain solution and I have a Gaussian source of 780 nm in wavelength propagating in air incident on 5 microns thick silicon. The rectangular simulation region is enclosed with 2 x wavelength thick PML region. I have the materials for the PML region behind the silicon slab set as silicon as well. The meshings are wavelength/32 for Silicon region (including the PML behind it) and wavelength/16 for everything else. For some reason I still get standing wave inside the silicon although it is absorbed by the PML. I tried messing with the scaling factor but it does not do anything. Does anybody know a way around this problem? I'm aware that increasing the silicon thickness to the point of complete absorption will solve this, but it is not an option due to limited memory (besides silicon at 780nm has a very large absorption depth).
I also tried with setting the whole simulation region's material to silicon, and it still shows reflection in the PML boundary. It seems like the PML region does not work for different materials rather than air.
I also attached the file for the simulation setup.
Any help is greatly appreciated. Thank you
Rico
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1 Reply Last Post 26 avr. 2014, 17:13 UTC−4
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Posted:
1 decade ago
Guys, if you're having the same problem as me and can't find a solution yet you can try to work around it by creating a simple anti-reflective coating layer, which is a gradient refractive index ranging your materials' n to air n=1. This will decrease reflection coefficient from the discontinuity. It works well enough for my application. Hope this helps.