Dear Mahdiyeh I have your problem in dispersive and constant dielectric functions and actually i have found that it is "numerical dispersion" and it's common problem in FDTD method. you can find it in many papers and books (you need just Googling). Best way I have found to decrease the effect of this problem is increasing the resolution but it will increase your simulation time badly, see below post as well.
http://www.mail-archive.com/[email protected]/msg03570.html I am interested in any other solutions!!!! Best regards Mohammad ________________________________ From: mahdiyeh tajabady <[email protected]> To: [email protected] Sent: Wed, October 13, 2010 9:02:38 PM Subject: [Meep-discuss] dispersive material Dear Dr. Steven and meep users, I tried to find properties of dispersive material. I have some experimental data which I used them to find properties from analytical approach. it works well for materials with low dielectric constant like 2 or even 4 but it did not works for very dispersive material and high dielectric constant like Si. I do not know is that problem with my simulation or it is related to the material which has high imaginary part for index of refraction. it is not in agreement with analytical approach because of high imaginary part of index of refraction in broad range of frequencies. Also, dispersion can be seen in dispersive_material.ctl simulation even when we do not use dispersive material (constant dielectric function). it means that we should consider it as uncertainty in our simulation? Best regards Mahdieh
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