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Solving scattered field for two semi-infinite material

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Hi everyone,

I am now simulating plane wave incident on a air-water interface from air side. The two materials are both semi-infinite. PML and periodic condition is used in this case. It's like PML(air)->air->water->PML(water). The plane wave is written as exp(j*n*k*z) in the background field, where z is the propagation direction and n the refractive index. What confuses me is that suppose n=1, the air case, it will have reflection inside the water. The PML doesn't absorb the wave in the water. And of course in this case it will have reflection in the air. After changing n=1 to n=1.33 for the plane wave, everything is correct, only reflection in the air and no reflection in the water. Why I have to use refractive index from water to get the correct solution?

And if the situation is opposite, i.e. PML(water)->water->air->PML(air) and plane wave propagates from water side, I have to use n=1 to get correct solution. Does anyone know how this works?

Thanks,
Li-Fan

0 Replies Last Post 11 sept. 2015, 17:45 UTC−4
COMSOL Moderator

Hello Li-Fan Yang

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